IN THIS CHAPTER
Going into labor too soon
Monitoring preeclampsia, placental conditions, and amniotic fluid levels
Handling fetal growth problems, blood incompatibilities, and breech presentation
Waiting for baby beyond your due date
The vast majority of pregnancies are smooth, uncomplicated affairs — perfectly well managed by Mother Nature alone. Sometimes, though, your pregnancy can get a little complicated. Even when problems arise, ultimately both baby and mother are healthy in most cases. If you have no major medical problems going into your pregnancy and it remains uncomplicated, you may just as well skip this chapter. If, on the other hand, you’re the type of person who wants to know about every possibility — and this kind of knowledge doesn’t drive you nuts — you may find this chapter interesting.
This chapter’s information is meant to either reassure you that your pregnancy is safe or, if you do have some particular problem, provide useful information to help you understand the situation better.
Dealing with Preterm Labor
Normally, during the second half of pregnancy, the uterus contracts intermittently. As the end of your pregnancy approaches, these contractions grow more frequent. Finally, they become regular and cause the cervix to dilate. When contractions and dilation occur before 37 weeks of gestation, labor is considered preterm. Some women notice periods of regular contractions prior to 37 weeks. If the cervix doesn’t dilate or efface, however, the condition isn’t considered preterm labor.
Of course, the earlier preterm labor occurs, the more troublesome it can be. The problems that a premature baby has if he is born after about 34 weeks are usually much less worrisome than those he faces if born at only 24 weeks. Prior to about 32 weeks, the main problem is that the baby’s lungs may still be immature, but other complications may exist as well. Nevertheless, the majority of babies born at 26 to 32 weeks do just fine, especially if they have access to modern neonatal intensive care.
Premature babies stand a higher risk of contracting an infection, they may experience problems with the gastrointestinal tract (stomach and intestines), or they may experience an intraventricular hemorrhage, which is bleeding into an area in the brain.
The following can be signs and symptoms of preterm labor:
· Constant leakage of thin fluid from the vagina
· An increase in mucous-like vaginal discharge
· Intense and persistent pressure in the pelvis or vaginal area
· Menstrual-like cramps
· Persistent lower-back pain
· Regular contractions that don’t stop with rest or decreased activity
Focusing on high-risk categories
Nobody knows for sure what causes premature labor, but clearly, some patients are at higher risk for developing it. If you fall into one of the high-risk categories, your practitioner probably will want to follow you more closely than usual. Here are some factors that put you at risk for preterm delivery:
· An abnormally shaped uterus
· Bleeding during pregnancy, especially during the second half (not including occasional spotting during the first trimester)
· A prior preterm delivery
· Some infections, like bacterial vaginosis, periodontal disease, or a kidney infection
· Smoking
· Abuse of certain illicit drugs
· Being African-American
· Poor nutrition and/or a low pre-pregnancy weight
· Being pregnant with twins or more
A lot of women ask whether certain working conditions can increase the risks of preterm birth. There does seem to be some association between premature birth and physically demanding work, prolonged standing, shift or night work, and significant fatigue. However, having a demanding job doesn’t make preterm labor a certainty by any means.
The following suggestions can decrease your chances of preterm labor:
· Stop (or decrease) smoking. See Book 1, Chapter 2 for more on how smoking affects your baby.
· Avoid illicit drugs and alcohol. To find out more about the risks posed by the use of these substances, turn to Book 1, Chapter 2.
· Reduce occupational fatigue. Limit work to less than 42 hours per week, and minimize standing to less than 6 hours per day.
· Make sure you’re getting adequate nutrition and hydration. Check out Book 1, Chapter 3 for the details of a healthy diet.
· Try 17-hydroxyprogesterone caproate. If you have a history of spontaneous preterm delivery in a prior pregnancy, talk to your doctor about starting a medication called 17-hydroxyprogesterone caproate. See the later section “Preventing preterm labor” for information on this medication.
Some interventions that haven’t been shown to be helpful in lowering your chances of preterm labor are
· Bed rest and hospitalization
· Avoiding intercourse
· Taking medications that are typically used to stop premature labor after it has set in (called tocolytics as a group — see “Stopping preterm labor” later in this chapter) as a preventive step to keep it from starting
· Taking antibiotics unnecessarily
Although studies show these things haven’t been shown to be beneficial, they’re still sometimes prescribed in individual situations in the hope that they may help.
EXPECTANT MOTHERS ASK …
Q: “Is monitoring contractions from home an effective way to detect preterm labor?”
A: Home-contraction monitoring is a technology rarely used anymore because studies haven’t shown that it’s beneficial. Your practitioner gives you a device that you strap to your abdomen for a period of a half-hour to an hour each day (or sometimes twice a day). This device can sense contractions you may not be able to feel. The information that the device receives is then transmitted through a telephone modem to a nursing station. If it appears you’re contracting more frequently than you should be, the device alerts your doctor. In this way, you may pick up preterm labor at an early stage. However, recent studies suggest that this kind of monitoring is no more useful than having the patient keep in close contact with nurses or teaching the mom to be aware of preterm labor’s symptoms.
Checking for signs of preterm labor
Practitioners have various ways of detecting preterm labor, although the techniques aren’t always effective. The most common methods are for your practitioner to check your cervix by performing an internal exam and to monitor you for contractions.
Some practitioners look for symptoms of preterm labor using transvaginal ultrasound. A small ultrasound probe is placed into the vagina next to the cervix in order to measure the length of the cervix. Measuring cervical length can help predict whether you’re at an increased risk of delivering prematurely. If you’re found to have a shortened cervix and are considered high risk for preterm birth, vaginal progesterone may be helpful in decreasing your chances of delivering prematurely. The routine use of cervical ultrasound for the prediction of preterm birth in women without any symptoms or risk factors is controversial. More studies are needed to show doctors how best to use transvaginal ultrasound.
Interestingly, some researchers have found that a specific type of pessary, which is a device placed in the vagina and around the cervix, may also help decrease preterm delivery in singletons.
A test called fetal fibronectin is probably the best available predictor of who is not likely to have preterm delivery. The test involves swabbing the back of the vagina with a cotton swab. A negative result on this test is a good indicator that delivery is unlikely within the next few weeks. A positive result, however, doesn’t necessarily mean that you’re going to deliver prematurely.
Stopping preterm labor
Depending on how far along you are when you develop preterm labor, your doctor may attempt to stop your contractions (assuming he believes in this practice), and you may be admitted to the hospital. Your doctor may use several medications (called tocolytics) to block preterm labor.
Doctors have never come to widespread agreement that these medications are useful in the long run, although they have been shown to help for a few days to a week. Most tocolytics have side effects on the mother. Terbutaline is a medication that was commonly used until 2011, when the U.S. Food and Drug Administration (FDA) issued a warning regarding its use to treat preterm labor. The side effects of terbutaline include flushing and a feeling that your heart is racing. It can also make it easier for you to develop a serious condition known as pulmonary edema, in which water accumulates in your lungs. The data suggest that the use of terbutaline should be limited to short-term in-patient use to stop preterm labor. Two other types of medications have side effects as well: Magnesium sulfate may cause nausea, flushing, or drowsiness, and indomethacin is well-tolerated, but it can’t be used for too long because of some effects on the fetus with long-term use. Nifedipine has recently become the first line of treatment for many doctors because it appears to have few side effects and there are no restrictions on the length of use.
If your doctor thinks your preterm labor may lead to premature delivery prior to 34 weeks, he’ll probably recommend you receive an injection of steroids, which have been shown to decrease the risk of respiratory problems and other complications in the premature newborn. The risks to the mother of taking these drugs are negligible, and large studies have shown that the steroids are beneficial to the baby for about a week. Patients who continue to be at risk for preterm delivery a week after the steroids were first administered may be given a second course of steroids under certain circumstances. In particular, if you’re less than 28 weeks along and still at risk for preterm birth, a repeat course may be beneficial to the baby. Recent data suggests that using a lower dose of steroids for the second course is still beneficial and may have fewer long-term side effects.
Recently, magnesium sulfate has been used not for its anti-contractive effect but for its effectiveness in protecting the preterm fetal brain. Studies have shown that magnesium sulfate given to mothers shortly before delivering infants prior to 32 weeks reduces the chances of infant death as well as cerebral palsy.
Preventing preterm labor
Several recent studies indicate that women who are at an increased risk for a preterm delivery (see the earlier section “Focusing on high-risk categories”) may have a reduced chance of delivering preterm if they take a specific type of progesterone during their pregnancies. The studies looked at both progesterone injections and progesterone vaginal suppositories.
The injections involve weekly doses of a medication called 17-hydroxyprogesterone caproate (17-P) starting at 16 to 20 weeks and continuing until about 36 weeks. The suppositories involve placement of a tablet or gel into the vagina nightly starting at 16 to 24 weeks and continuing until 36 weeks.
At this time, progesterone injections seem effective for women with a history of a prior preterm birth and possibly for women with abnormally shaped uteruses or cervical insufficiency. Recent studies suggest that high-risk women diagnosed with a shortened cervix may also benefit from progesterone therapy. Vaginal progesterone — either 90 mg gel or 200 mg suppository — can help reduce preterm birth in women with singleton gestations, without a history of a prior preterm birth, and with a short cervix found on ultrasound prior to 24 weeks. There currently isn’t good enough data to recommend progesterone to women carrying twins or more.
Delivering the baby early
Sometimes delivering a baby early makes sense. When a woman experiences preterm labor at 35 or 36 weeks, for example, letting her go ahead and deliver is usually wise because the outlook for the baby is so good that there’s no reason to subject the mother to the side effects of medications to forestall labor. Regardless of the gestational age, premature delivery may also be the best option in cases where the baby has a condition that doctors can’t treat inside the uterus or when the mother has a condition that is worsening, such as preeclampsia (see the next section), and continuing the pregnancy would be risky.
FOR PARTNERS: NAVIGATING THE NICU
The neonatal intensive care unit (NICU) is like nothing you’ve ever seen before. Although hospitals put more emphasis than they used to on keeping NICUs quiet, they are, by necessity, fairly noisy and busy, with alarms going off, lights on day and night so hospital personnel can see what they’re doing, and at the center of it all, your little baby. She may be hooked up to just a single monitor or perhaps so laden down with medical equipment and IV lines that you can scarcely find her.
The best way to deal with the NICU is to focus on your little part of the world. Get to know your baby’s nurses and stay near your baby’s incubator. Asking what’s wrong with other babies is really bad etiquette, and the nurses won’t (or shouldn’t) tell you, anyway.
Preterm babies are often moved from the hospital where they’re born to a level 3 nursery with advanced technology to handle complicated preterm issues. This can make your life difficult, especially if the new hospital is some distance from your house, but your baby’s care is ultimately worth it.
Some hospitals with large, regional NICUs have facilities that allow parents to stay overnight for a small charge or for free. Ronald McDonald houses are examples of facilities available near some hospitals.
If your partner is still in the hospital and can’t see the baby right away, make sure you take lots of pictures — not just of the baby but also of the neonatal unit and, if possible, of the people taking care of her. That way your partner can get a real sense of where the baby is and picture her in an actual place. Some regional NICUs provide a video feed to community hospitals so that moms who are separated from their babies can maintain a connection until they have a chance to see the baby in person.
Handling Preeclampsia
Preeclampsia — also known as toxemia or pregnancy-induced hypertension (PIH) — results when a woman experiences elevated blood pressure along with some other laboratory abnormalities or symptoms after about 20 weeks of gestation. This condition isn’t all that uncommon, occurring in about 7 percent of pregnancies. Women having their first child are especially susceptible. Preeclampsia usually occurs late in pregnancy, but it can develop in the late second or early third trimester. The condition goes away after delivery.
Making a diagnosis
Doctors have different criteria for diagnosing the condition, but in general, blood pressure that stays above 140/90 is considered elevated if you have no history of blood pressure problems prior to pregnancy.
Recently, the criteria to diagnose preeclampsia have changed. Following are the current criteria:
· Recurring high blood pressure: Systolic blood pressure ≥ 140 mm Hg or diastolic blood pressure ≥ 90 mm Hg on two occasions at least 4 hours apart after 20 weeks in a patient without any history of chronic hypertension
· Protein in the urine (proteinuria): Protein in the urine of ≥ 0.3 g in a 24-hour urine specimen or protein/creatinine ratio of ≥ 0.3 mg/dL or a dipstick urine protein of 1+
· Other factors: In a patient with new-onset hypertension without proteinuria, the new onset of any of the following is also diagnostic of preeclampsia:
· Platelet count < 100,000/microliter
· Serum creatinine > 1.1 mg/dL or doubling of serum creatinine in the absence of other renal disease
· Certain liver enzymes at least twice normal
· Pulmonary edema (fluid in the lungs)
· Cerebral or visual symptoms
The presence of one or more of the following criteria is a feature of severe preeclampsia:
· Symptoms of central nervous system dysfunction
· New-onset cerebral or visual disturbances, severe headache, or altered mental status
· Liver abnormalities
· Severe persistent pain just under your rib cage on the right or in the middle just under your breastbone (sternum)
Many of these symptoms can occur harmlessly during any pregnancy. Unless they happen in combination with elevated blood pressure or protein spillage in the urine, they’re quite normal. If one day you have a headache, or if for a second you see spots, don’t jump to the conclusion that you have preeclampsia. If the symptoms persist, though, tell your doctor.
Examining risk factors
No one knows exactly what causes preeclampsia, but it probably involves a combination of maternal, fetal, and placental factors. Some women are at a higher risk of developing it than others. Here are risk factors for preeclampsia:
· Existing chronic hypertension
· First pregnancy
· History of preeclampsia in a prior pregnancy
· Long-standing diabetes
· Mother older than 40
· Significant obesity
· Medical problems such as serious kidney or liver disease, lupus, or other vascular diseases
· Triplets or more (twins also but to a much lesser extent)
Considering treatments
Despite extensive ongoing medical research on preeclampsia, no one knows exactly how to prevent it. Some data suggests that taking a low dose of aspirin daily starting at 12 to 14 weeks may help reduce the incidence of preeclampsia or delay its onset for women at moderate to high risk of developing the condition. Other treatments have been tried with varying degrees of success, including the following:
· Calcium supplementation and antioxidant therapy: Like low-dose aspirin, calcium hasn’t been shown to prevent preeclampsia in low-risk women; however, there may be some benefit to women at high risk.
· A combination of vitamins C and E: Although initial studies suggested a benefit, more recent data shows not only no benefit but also a higher risk of certain complications.
· Fish oil: This has been investigated, but it hasn’t been shown to be helpful in lowering the incidence of preeclampsia.
Ultimately, the only real treatment for preeclampsia is delivering the baby. When to deliver depends on how severe the condition is and how far along you are in your pregnancy. If you’re close to your due date, induced delivery may be the wisest approach. If you’re only 28 weeks along, your doctor may try close observation of you and the baby, either at home or in the hospital. Doctors weigh the risks to the mother’s health against the risks to the baby of preterm delivery.
Understanding Placental Conditions
Two problems with the baby’s placenta can occur in the latter part of pregnancy: placenta previa and placental abruption. This section describes both.
Placenta previa
Placenta previa occurs when the placenta partially or completely covers the cervix, as shown in Figure 2-1. Doctors typically diagnose patients with placenta previa during a routine ultrasound exam, but sometimes women find out about the problem only when they begin bleeding late in the second trimester or early in the third.
Illustration by Kathryn Born, MA
FIGURE 2-1: Placenta previa.
In early pregnancy, having the placenta positioned near the cervix or even partially covering it is common and usually poses no danger to the mother or the baby. In fact, this condition occurs in as many as one out of five pregnancies. In the vast majority of women (95 percent), the placenta rises as the uterus enlarges with the growing baby, which is why you have no reason to worry about the placenta covering the cervix early in pregnancy.
Even if the situation persists through the late second trimester and into the third, it can be harmless. Many women who have placenta previa never bleed at all. However, the possibility of heavy bleeding is the main concern with placenta previa. Sometimes bleeding leads to preterm labor. In this case, your practitioner attempts to stop the contractions, which often stops the bleeding. If bleeding is severe and can’t be stopped, the baby may have to be delivered.
If you’re in your third trimester and you have placenta previa, your practitioner may want you to have regular ultrasound examinations to see whether the placenta will eventually move out of the way. These are usually transvaginal ultrasounds and are safe to use with a placenta previa in experienced hands. Your doctor may tell you to avoid intercourse and not undergo internal (digital) examinations in order to lower the risk of any bleeding. If the condition persists until 36 weeks, he’ll most likely recommend a cesarean delivery because the baby can’t come through the birth canal without disrupting the placenta, which can lead to heavy bleeding.
Placental abruption
In some women, the placenta separates from the uterine wall before pregnancy is over. This condition is called placental abruption (it’s sometimes also called abruptio placentae or placental separation). Figure 2-2 shows you what it looks like.
Illustration by Kathryn Born, MA
FIGURE 2-2: Placental abruption.
Placental abruption is a common cause of third-trimester bleeding. Because blood is an irritant to the uterine muscle, it can also cause premature labor and abdominal pain. An abruption is difficult to see on an ultrasound exam unless it’s quite large, so in many cases, doctors can make the diagnosis only after they rule out every other possible cause of bleeding. Rarely, a placental abruption occurs suddenly, and if the separation is large enough, it may necessitate rapid delivery. See Book 2, Chapter 3 for other causes of third-trimester bleeding.
If you experience a small placental abruption, your practitioner may recommend you try bed rest. He’ll also start to observe your pregnancy more closely to make sure the problem has no harmful side effects on the fetus.
Recognizing Problems with the Amniotic Fluid and Sac
As you know, the fetus grows within a “bag of water” known as the amniotic sac, which contains the amniotic fluid. This fluid increases in volume throughout the first part of pregnancy and reaches its maximum level at 34 weeks. After that, the volume gradually declines. Medical science hasn’t yet discovered exactly what mechanism regulates the amniotic fluid volume, although it is known that the fetus plays some role in how much fluid the sac contains. During the second half of pregnancy, the amniotic fluid comprises mainly fetal urine. The fetus urinates into the sac and then swallows the fluid. The fluid circulating around the fetal lungs aids in lung development.
Sometimes, a practitioner may suspect that the amount of amniotic fluid is above or below average, and he may do an ultrasound examination to see what’s happening. Minor increases or decreases in the amount of amniotic fluid usually aren’t a problem. But large variations in amniotic fluid volume may be a symptom of some other problem. This section describes what happens when problems with the amniotic fluid or sac occur.
Too much amniotic fluid
The medical term for too much fluid is polyhydramnios or hydramnios. This situation occurs quite frequently, in about 1 to 10 percent of pregnancies. Often the increase in volume is small. Doctors don’t always know what causes it, but they do know that a small increase usually isn’t a problem. Larger increases may be associated with a medical condition in the mother — diabetes or certain viral illnesses, for example. In some rare cases, the excess fluid may be due to certain fetal problems. The fetus may be having difficulty swallowing the fluid, for example, so more of it accumulates inside the sac.
Usually the fluid isn’t increased to the point where it causes significant problems, but on rare occasions there can be massive accumulations of fluid to the point that it becomes difficult for the mom to breathe and causes the uterus to contract prematurely (premature labor). If this happens and Mom is near her due date, then her doctor will most likely recommend delivery to relieve the discomfort. If, however, she is remote from her due date, then doctors can remove some of the fluid during an amniocentesis to make Mom more comfortable. Also, indomethacin has occasionally been used in this setting because one of the side effects of indomethacin is that it causes amniotic fluid volume to decrease.
EXPECTANT MOTHERS ASK …
Q: “Is the amount of amniotic fluid determined to any extent by the amount of water I drink?”
A: No. The mother’s fluid intake has little to do with it. Some recent studies suggest a mother can cause small increases in the amount of amniotic fluid by drinking plenty of liquids, but the effect isn’t that great. Nevertheless, stay well hydrated.
Too little amniotic fluid
A woman who has too little amniotic fluid has oligohydramnios. As mentioned earlier, amniotic fluid volume normally decreases after 34 to 36 weeks. If yours starts to fall below a specific range, however, your practitioner may want to observe the fetus more closely by performing certain tests. One common cause of low amniotic fluid is a rupture of the membranes, which allows fluid to leak out.
A fluid level that drops significantly prior to 34 weeks may indicate a problem with the mother or the baby. For example, some women with hypertension or lupus may have less blood flow to the uterus and, consequently, less blood flow to the placenta and the baby. When the baby receives less blood, the baby’s kidneys make less urine, and that results in lower levels of amniotic fluid.
If the reduction in fluid is mild or moderate, the baby is watched carefully and undergoes tests of fetal well-being. Sometimes, oligohydramnios is a sign that the baby’s growth is restricted (see the later section “Describing Problems with Fetal Growth”) or, rarely, that there are abnormalities in the baby’s urinary tract. Sometimes it’s a sign the placenta isn’t functioning optimally.
If you have decreased amniotic fluid, your doctor may suggest you get more rest and try to stay off your feet. By doing so, you may promote more blood flow to the uterus and placenta and thus increase the baby’s urine output. (Just be glad you don’t have to change all the diapers yet!)
Rupture of the amniotic sac
Premature rupture of the membranes or amniotic sac, sometimes called PROM, occurs when a woman’s water breaks sometime before labor starts. When it happens close to your due date, it’s referred to as term PROM. If you’re less than 37 weeks at the time, it’s called preterm PROM.
· If you experience term PROM: Your practitioner may simply wait until you go into labor on your own. Or he may induce labor in order to avoid the risk of an infection developing inside the uterus.
· If you experience preterm PROM: You may or may not go into labor, depending on how far along you are. If you’re very far from your due date and don’t appear to have an infection in your uterus, your doctor may use some medications (antibiotics, tocolytics, and steroids) to prolong the pregnancy as long as possible and to help your baby’s chances of lung development. Your doctor will probably perform frequent ultrasound exams and monitor the fetal heart rate to ensure the baby is managing okay.
If you think your membranes may have ruptured and you’re preterm, let your practitioner know immediately or go to the hospital. He can perform tests to definitively let you know whether the membranes have ruptured.
Describing Problems with Fetal Growth
One of the main reasons to get prenatal care is to ensure that your baby is growing well. A practitioner typically gauges growth by measuring the fundal height (see Book 1, Chapter 2). As a general rule (in a singleton pregnancy), the measurement in centimeters from the top of the pubic bone to the top of the uterus roughly equals the number of weeks gestation. If your practitioner finds this measurement is greater or less than expected, he may recommend you have an ultrasound exam to more precisely assess the baby’s growth.
During the exam, the technician measures various fetal body parts to come up with an approximate fetal weight. That estimate is then compared with the average weight for fetuses at the same gestational age and assigned to a certain percentile. The 50th percentile is average. But because fetuses (like babies, toddlers, children, teenagers, and grown-ups) come in different sizes, there’s a range of normal weights. Anything between the 10th and the 90th percentiles is considered normal (see Book 2, Chapter 3 for more information about fetal weight).
These upper and lower limits are somewhat arbitrary. They do imply that 10 percent of the population is larger than normal and that 10 percent is smaller, but this statement isn’t exactly true. Most fetuses below the 10th percentile or above the 90th percentile are completely normal. On the other hand, some of them may not be growing normally and may need extra surveillance.
Smaller-than-average babies
A fetus whose estimated weight falls below the 10th percentile may have intrauterine growth restriction (IUGR). IUGR can lead to the birth of a baby who is small for gestational age (SGA). IUGR has many possible causes, including the following:
· Normal variations: The baby is measuring small but is otherwise normal. Just as healthy adults come in all sizes, so do fetuses.
· Chromosomal abnormalities: This cause is most common with early-onset IUGR, which occurs in the second trimester.
· Environmental toxins: Cigarette smoking causes a decrease in birth weight between ¼ and ½ pound, on average. Chronic alcohol consumption (at least one to two drinks a day) and cocaine use also can cause low birth weight.
· Genetic factors: Some genetic factors cause the fetus to grow less than average.
· Heart and circulatory abnormalities in the fetus: Examples include a congenital heart defect or umbilical cord abnormalities.
· Inadequate nutrition for the mother: Proper nutrition is especially important in the third trimester.
· Infection such as cytomegalovirus (CMV), rubella, or toxoplasmosis: Book 6, Chapter 3 provides more information.
· Multiple gestation: Fifteen to 25 percent of twins, and an even higher percentage of triplets, have IUGR. Twins grow at the same rate as singletons until 28 to 32 weeks, when the twin growth curve drops off.
· Placental factors and uterine-placental problems: Because the placenta provides nutrition and oxygen to the fetus, if it’s functioning poorly or if the blood isn’t flowing smoothly from the uterus to the placenta, the fetus may not grow properly. Women with antiphospholipid antibody syndrome (a blood-clotting problem), recurrent bleeding, vascular diseases, or chronic hypertension are at risk for IUGR because those conditions cause poor placental function. Preeclampsia (described earlier in this chapter) may also impair placental function and lead to IUGR.
The way your practitioner responds to IUGR depends on your individual situation. Fetuses with mild IUGR, normal chromosomes, and no evidence of infection are likely to be fine. Sometimes early delivery is warranted, however, because the fetus may grow better in the nursery than inside the uterus. The way your practitioner responds to signs of IUGR depends on both the cause of the problem and the gestational age at which it’s diagnosed. He may recommend more frequent office visits, periodic ultrasound examinations, fetal heart rate exams (known as NSTs — see Book 2, Chapter 3), or other tests such as a biophysical profile (an ultrasound assessment of fetal well-being) and measurement of blood flow through the umbilical cord called Dopplers. If the problem is severe but the pregnancy is far enough along, your doctor may recommend delivery.
In many cases, SGA babies turn out to be perfectly normal. Unfortunately, though, severe cases have been associated with learning difficulties later in life and even fetal death, which is why having your practitioner conduct some form of fetal surveillance is important.
EXPECTANT MOTHERS ASK …
Q: “If I eat more, will my baby grow into the normal range?”
A: Unfortunately, the answer is no. Eating more doesn’t correct the problem unless you’re significantly malnourished.
Larger-than-average babies
A baby whose estimated weight is above the 90th percentile may have macrosomia (“big body”) and end up being large for gestational age, or LGA. The risk factors of having an exceptionally large baby include the following:
· The mother has previously delivered a large baby.
· The mother has gained an excessive amount of weight during the pregnancy.
· The mother is obese.
· One or both of the parents were born very large.
· The pregnancy lasts longer than 40 weeks.
· The mother has poorly controlled diabetes.
The mother’s main risk, naturally, is that the delivery is more difficult. If she delivers vaginally, she may suffer increased trauma to the birth canal, and she has an increased chance of needing a cesarean delivery. The main risk to the baby, likewise, is injury during delivery. Birth injury is more likely when a large baby is delivered vaginally, but it can also occur during a cesarean delivery. Most commonly, birth injury involves excessive stretching of the nerves in the baby’s upper arm and neck resulting from shoulder dystocia (see Book 2, Chapter 5) during delivery.
If your practitioner thinks your baby may be exceptionally large, based on either an ultrasound estimate of fetal weight or an abdominal exam, and it appears your pelvic bones may make for a tight fit, he’ll discuss your delivery options with you.
Looking at Blood Incompatibilities
If a baby’s parents have different blood types, the baby’s blood type can differ from the mother’s. Usually this situation creates absolutely no problem for the mother or the baby. In some rare cases, these blood-type mismatches warrant special consideration. Even then, however, there’s hardly ever a significant problem.
The Rh factor
Most people are Rh-positive, which means they carry the Rh factor on their red blood cells. Those who don’t carry the Rh factor are considered Rh-negative. If an Rh-positive man and an Rh-negative woman conceive, the fetus may be Rh-positive, thereby creating a mismatch between the baby and mother.
This kind of mismatch usually isn’t a problem and is almost never a problem in a first pregnancy. If, however, any of the baby’s blood leaks into the mother’s circulation, her immune system may form antibodies to the Rh factor. And if any such antibodies reach a significant level in a future pregnancy, they can cross through the placenta into the baby’s circulation and begin to destroy the baby’s red blood cells.
The problem sounds scary, but it isn’t insurmountable. The doctor usually gives the mother an injection of anti-D immune globulin at certain times to prevent the formation of antibodies. Rhogam and Rhophylac are two common preparations of anti-D globulin. If your baby’s father is Rh-positive and you’re Rh-negative, your doctor may recommend that you receive anti-D immune globulin at the following times:
· Routinely at about 28 weeks gestation (as a precaution, just in case any passage of blood across the placenta has already occurred) and again 12 to 13 weeks later, if you haven’t already delivered
· After amniocentesis, CVS (chorionic villus sampling), or any invasive procedure (see Book 2, Chapters 2 and 3)
· After a miscarriage, abortion, or ectopic pregnancy (see Book 2, Chapter 1 for more on ectopic pregnancy)
· After significant trauma to your abdomen during pregnancy, if your doctor thinks that some of the baby’s blood may have leaked into your circulation
· After significant bleeding during pregnancy
· Within 72 hours of delivery (either vaginal or cesarean); a nurse gives you the injection after delivery to prevent problems in future pregnancies
In unusual circumstances — either when the anti-D immune globulin wasn’t given but should have been (very rare) or when it didn’t work effectively (exceedingly rare) — a mother produces antibodies to the Rh factor. Then, if she becomes pregnant again, an Rh-positive fetus may be at risk of developing anemia (not enough red blood cells), depending on the levels of antibodies in the mother’s blood and how they interact with the baby’s blood. The anemia may be mild, requiring only that the baby be placed under special lights in the nursery to clear any extra bilirubin (a pigment that’s released from red blood cells that are destroyed). If you’ve been sensitized and have developed these antibodies, your doctor can perform tests on amniotic fluid to check the baby’s Rh status. If the fetus is Rh(D)-negative, he isn’t at risk of anemia, even though the mother has the antibodies.
In moderate cases, frequent ultrasound exams may be necessary to assess the situation’s severity. Recently, a new technique using ultrasound to measure the blood flow through one of the blood vessels in the fetus’s brain (the middle cerebral artery, or MCA) has emerged as the best method for predicting fetal anemia in at-risk pregnancies. If the mother is close to her due date, her practitioner may recommend an early delivery. In the most severe cases, the baby may need to have a blood transfusion while he’s still inside the uterus. The procedure is called a fetal blood transfusion, and a maternal–fetal medicine specialist performs it. A transfusion is the worst-case scenario, but even if things become this severe, a baby who has transfusions in a timely fashion can be born healthy. However, this procedure is associated with some risks.
Determining the baby’s Rh(D) status by detecting fetal DNA in the mother’s blood is now possible. Practitioners in Europe routinely use this method, and it will probably become part of the routine prenatal care of Rh(D)-negative women in the future in the United States. This test allows sensitized women to avoid invasive procedures for determining the fetal blood type, and it allows some women who aren’t sensitized to avoid the anti-D immune globulin injection.
Other blood mismatches
Other kinds of blood mismatches are possible. Kell, Duffy, and Kidd are a few examples of blood factors that can differ between mother and baby. Fortunately, all these factors are very rare. No Rhogam-like medications are available to treat these mismatches, but if a problem does occur, your practitioner can provide care for the baby in the other ways described for Rh incompatibility (special lights, early delivery, or blood transfusion). And these babies, too, are usually born healthy.
Finally, some blood group antibodies — Le, Lu, and P, for example — can be mismatched but have no harmful effects on the fetus. Usually, no special action is needed.
Dealing with Breech Presentation
A baby is in a so-called breech position when her buttocks or legs are down, closest to the cervix. Breech presentation happens in 3 to 4 percent of all singleton deliveries. A woman’s risk of having a breech baby decreases the further along she goes in her pregnancy.
The fetus is more likely to assume a breech position for one of the following reasons:
· The fetus is preterm or especially small.
· An increased amount of amniotic fluid exists (all the more room to turn around in).
· A congenital malformation of the uterus is present, such as a bicornuate (T-shaped) uterus.
· Fibroids that impinge on the uterine cavity are present.
· You have placenta previa (described earlier in this chapter).
· You’re having twins or more.
· Your uterus is relaxed from having had several babies already.
If your baby is in a breech position, your will doctor talk with you about the potential risks and benefits of a vaginal breech delivery versus version (turning the baby) or cesarean section. Special concerns about a breech delivery include the following:
· Trapping the baby’s head (which comes out last in a breech delivery) in a cervix that has been incompletely dilated by the passage of the baby’s body, which is smaller than the head (this situation is especially troublesome if the baby is very small or premature)
· Trauma resulting from an extended fetal head (meaning the head is tilted back)
· Difficulty delivering the arms, which can lead to arm injuries
Because of these potential problems, many practitioners recommend that all breech babies be delivered by cesarean section. However, some fetuses in breech position are actually good candidates for vaginal delivery. Conditions that should be present for you and your doctor to consider a vaginal breech delivery include the following:
· Estimated fetal weight is between 4 and 8 pounds.
· The baby is in a frank breech position, which means the buttocks, not the feet, are positioned to come out first.
· The buttocks are engaged in the pelvis.
· Your doctor doesn’t detect (by physical exam or by X-ray) any problem with the baby’s head fitting through the birth canal.
· Ultrasound shows the fetal head is either flexed (chin to chest) or in the military position (looking straight ahead, not tilted back).
· Immediate anesthesia is available so that cesarean delivery can be done in an emergency.
· The doctor is experienced in vaginal breech deliveries.
A few recent large studies have shown that breech babies delivered vaginally are at a higher risk for certain complications. In fact, the information is so compelling that most obstetricians have stopped performing vaginal breech deliveries. However, studies show that while the short-term complications were higher in the babies born vaginally, there was no difference in long-term problems (combined death and neurodevelopmental delays) at 2 years of age.
If you and your practitioner decide that a vaginal breech delivery isn’t right for you, another option is external cephalic version, a procedure in which the doctor tries to turn the baby into normal delivery position by externally manipulating the mother’s abdomen, which is a common and usually safe procedure. Sometimes it’s fairly uncomfortable, but it works in about 50 to 70 percent of cases. The use of spinal or epidural anesthesia for the version may decrease the discomfort for the mother and improve the chances of successfully turning the baby.
There are certain conditions in which external cephalic version isn’t advisable, such as bleeding, low amniotic fluid level, or multiple gestations.
Pondering Post-Term Pregnancy
The average pregnancy lasts about 40 weeks (or 280 days) after the last menstrual period, but only about 5 percent of women deliver on their due date. Some deliver a couple of weeks earlier, and some, a couple of weeks later, and all are considered to be “at term.” Here are the most recent definitions of term pregnancy:
· Early term: 
weeks through 
weeks
· Full term: 
weeks through 
weeks
· Late term: 
weeks through 
weeks
· Post term: 
weeks and beyond
Why should you or your practitioner care whether you go past your due date? Because the chances of certain complications rise as time goes on. From 40 to 42 weeks, the increased risks are small, but after 42 weeks, they climb into a range that’s more worrisome. The worst complication is perinatal death (also called perinatal mortality). The chances of perinatal death start to increase after 41 to 42 weeks and double by 43 weeks.
This situation isn’t as scary as it may sound, though, because the actual number of deaths is so low. The vast majority of late babies are born healthy. Even at 44 weeks (the point at which perinatal mortality rates quadruple), 95 percent of babies are fine if appropriate testing is done. Your doctor can help you make the best decision for you as to the safe timing of delivery.
The increase in mortality rates in post-date pregnancies involves several factors, including the following:
· The placenta can function efficiently for only a finite length of time — about 40 weeks. Fortunately, most placentas have some amount of “reserve,” and they still work well beyond 40 weeks. But in a few rare cases, they don’t last as well. If a placenta can’t get enough nutrients to the baby, the baby may actually lose some weight by remaining inside the uterus.
· In a post-term pregnancy, the volume of amniotic fluid may decrease. As mentioned earlier in this chapter, amniotic fluid volume peaks at about 34 to 36 weeks gestation and starts to slowly drop after that. Most of the time, adequate fluid is left after 40 weeks. Sometimes, however, the fluid level drops into a range doctors consider too low. In this situation, the umbilical cord has a chance of becoming compressed, and doctors may recommend that labor be induced.
· Babies sometimes pass their first bowel movement while they’re still in the uterus. The longer a pregnancy lasts, the more likely this is. In rare instances, the baby breathes in this thick meconium before or during birth, which can cause problems with breathing in the first few days or weeks after birth (for more information, see Book 2, Chapter 6).
· In a post-term pregnancy in which the placenta continues to function normally, the baby keeps growing. These late babies are more likely to be very large, or macrosomic (see the earlier section “Describing Problems with Fetal Growth”).
Practitioners use various strategies to manage post-date pregnancies, none of which is inherently better than another. Some doctors want to be sure all babies are delivered as soon after 40 weeks as feasible and induce labor to ensure that they are. (See Book 2, Chapter 4 for information on labor induction.) Others are willing to wait longer for spontaneous labor. The argument for the first approach is that you don’t have to worry about any of the aforementioned complications. With the second approach, on the other hand, you may have less chance of needing a cesarean delivery.