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Week 31
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How Big Is Your Baby?

Your baby continues to grow. It weighs about 3.5 pounds (1600g), and crown-to-rump length is 11.2 inches (28cm). Its total length is 18 inches (40cm).

How Big Are You?

Measuring from the pubic symphysis, it is now a little more than 12 inches (31cm) to the top of the uterus. From your bellybutton, it is about 4.4 inches (11cm).

At 12 weeks gestation, the uterus was just filling the pelvis. As you can see in the illustration on page 257, by this week the uterus fills a large part of your abdomen.

Your total pregnancy weight gain by this time should be between 21 and 27 pounds (9.45 and 12.15kg).

How Your Baby Is Growing and Developing

Intrauterine-Growth Retardation

Intrauterine-growth retardation (IUGR) indicates a newborn infant is small for its gestational age. By definition, its birth weight is below the 10th percentile for the baby's gestational age (the lowest 10%). This means 9 out of 10 babies of normal growth are larger.

When gestational age is appropriateùmeaning dates are correct and the pregnancy is as far along as expectedùand weight falls below the 10th percentile, there is reason for concern. Growth-retarded infants have a higher rate of death and injury than infants in the normal-weight range.

Causes of IUGR

What causes intrauterine-growth retardation? Below are some conditions that increase the chance of intrauterine-growth retardation or a small fetus.

Smoking and other tobacco use inhibits the baby's growth. The more cigarettes smoked, the greater the impairment.

Poor weight gain in the mother-to-be can cause problems in the baby. If a woman is average size or smaller and doesn't gain enough weight, it may result in a growth-retarded baby. This is one of the reasons that good nutrition and a healthful diet are so important during pregnancy. Do not attempt to restrict normal weight gain during pregnancy. Research indicates that when calories are restricted to under 1500 calories a day for an extended time, IUGR may result.

Maternal blood-flow problems, particularly pre-eclampsia, may cause IUGR. A more common problem is high blood pressure (hypertension), which can have a marked effect on fetal growth.

Kidney disease in a pregnant woman can cause retardation of fetal growth. Women who live at high altitudes are also more likely to have babies that weigh less than those born to women who live at lower altitudes.

Alcoholism can cause intrauterine-growth retardation. Drug use and abuse can also cause IUGR. Multiple fetuses may result in smaller fetal growth. Infections in the fetus, such as cytomegalovirus, rubella or other infections, may also restrict fetal growth.

Maternal anemia may be another cause of IUGR. (Anemia is discussed in depth in Week 22.) However, not every authority accepts maternal anemia as a cause of intrauterine-growth retardation.

Abnormalities of the umbilical cord or placenta may cause inhibited growth because the baby has received less nutrition during pregnancy. A woman who has delivered a growth-retarded infant may be more likely to do so again in subsequent pregnancies.

Other reasons for a small baby, unrelated to IUGR, include the fact that that a woman who is small might have a small baby. Prolonged pregnancy can lead to an undernourished, smaller baby. A malformed or abnormal fetus may also be smaller, especially when chromosomal abnormalities are present.

Diagnosing and Treating Intrauterine-Growth Retardation

Diagnosing IUGR can be difficult. One reason your doctor measures you at each visit is to see how your uterus is growing. A problem is usually found by measuring the uterus over a period of time and finding no change. If you measured 10.8 inches (27cm) at 27 weeks gestation and at 31 weeks you measure only 11 inches (28cm), your doctor might become concerned about IUGR and order tests.

Diagnosis of this type of problem is one important reason to keep all your prenatal appointments. You may not like being weighed at every appointment, but it helps your doctor see that your pregnancy is growing and the baby is getting bigger.

Intrauterine-growth retardation can be diagnosed or confirmed by ultrasound. Ultrasound may also be used to assure that the baby is healthy and no malformations exist that must be taken care of at birth.

When IUGR is diagnosed, avoid doing anything that could make it worse. Stop smoking. Improve your nutrition. Stop using drugs and alcohol.

Bed rest is another treatment. Resting enables the baby to receive the best blood flow, and better blood flow is the best chance it has to improve growth. If IUGR is caused by maternal disease, attempts are made to improve the mother's general health.

An infant with intrauterine-growth retardation is at risk of dying before delivery. To avoid this, it may require delivering the baby before it is full term. Infants with IUGR may not tolerate labor well; a C-section is more likely because of fetal distress. The baby may be safer outside the uterus than inside in some cases.

Changes in You

What Is Pre-eclampsia during Pregnancy?

Pre-eclampsia, once called toxemia of pregnancy, describes a variety of conditions that occur only during pregnancy or shortly after delivery. For our discussion, I will use the term pre-eclampsia to simplify matters. Pre-eclampsia problems are characterized by a collection of symptoms, including:

ò swelling (edema)

ò protein in the urine (proteinuria)

ò hypertension (high blood pressure)

ò a change in reflexes (hyperreflexia)

Other nonspecific, important symptoms of pre-eclampsia include pain under the ribs on the right side, headache, seeing spots or changes in vision. These are all warning signs. Report them to your doctor immediately, particularly if you've had blood-pressure problems during pregnancy!

Pre-eclampsia can progress to eclampsia. Eclampsia refers to seizures or convulsions in a woman with pre-eclampsia. Seizures are not caused by a previous history of epilepsy or a seizure disorder.

Most pregnant women have some swelling during pregnancy; swelling in the legs does not mean you have pre-eclampsia. You must have some other symptoms of pre-eclampsia as well. It is also possible to have hypertension during pregnancy without having pre-eclampsia.

What Causes Pre-eclampsia?

No one knows what causes pre-eclampsia or eclampsia. It occurs most often during a woman's first pregnancy. Women over 30 years old who are having their first baby are more likely to develop high blood pressure and pre-eclampsia.

Treating Pre-eclampsia

The goal in treating pre-eclampsia is to avoid eclampsia (seizures). That means keeping a close watch on you throughout pregnancy, and checking your blood pressure and weight at every prenatal visit.

Weight gain can be a sign of pre-eclampsia or worsening pre-eclampsia. Pre-eclampsia affects weight gain because it increases water retention. If you notice any symptoms, call your doctor's office.

Treatment of pre-eclampsia begins with bed rest at home. You may not be able to work or to spend much time on your feet. Bed rest allows for the most efficient functioning of your kidneys and blood flow to the uterus.

Lie on your side, not on your back. Drink lots of water. Avoid salt, salty foods and foods that contain sodium, which may make you retain fluid. Diuretics, which were used in the past, are not prescribed to treat pre-eclampsia today. They are not recommended.

If you can't rest at home in bed or if symptoms do not improve, your doctor may have to admit you to the hospital or deliver your baby. A baby is delivered for the following reasons:

ò for your well-being

ò to avoid seizures in you

ò for the baby's well-being

During labor, pre-eclampsia may be treated with magnesium sulfate. It is given in an I.V. to prevent seizures during and after delivery. High blood pressure may be treated with antihypertensive medication.

If you think you've had a seizure, call your doctor immediately! Diagnosis may be difficult. It may be helpful to have someone who observed the possible seizure describe it to your doctor. Eclampsia (seizure) is treated with medications similar to those prescribed for seizure disorders (see Week 26).

How Your Actions Affect Your Baby's Development

Sleeping Positions

I've already described the importance of resting on a regular basis and lying on your side when you sleep. (See Week 16.) Now is when it will pay off. You may notice you begin to retain water if you don't lie on your side when sleeping or resting. Lying on your side could help you feel better quickly.

Visiting Your Doctor

It's important to keep appointments with your doctor. It may seem to you that not much happens at these visits, especially when everything is normal and going well. But the information your healthcare provider collects tells him or her a lot about your condition and your baby's.

Your doctor is watching for signs that tell him or her you might have a problem, such as changes in your blood pressure, changes in your weight or the inadequate growth of the baby. If these problems are not discovered early, they may have serious consequences for you and your baby.

You Should also Know

Pregnancy-induced Hypertension

Pregnancy-induced hypertension occurs only during pregnancy. With hypertension of pregnancy, the systolic pressure (the first number) increases to higher than 140ml of mercury or a rise of 30ml of mercury over your beginning blood pressure. A diastolic reading (the second number) of over 90 or a rise of 15ml of mercury also indicates a problem. An example is a woman whose blood pressure at the beginning of pregnancy is 100/60. Later in pregnancy, it is 130/90. This indicates she may be developing hypertension or pre-eclampsia.

Your doctor will be able to determine if your blood pressure is rising to a serious level by checking it at every prenatal appointment.

You Can Affect Blood Flow to Your Legs and Arms

Margo couldn't get her shoes on after she'd been up for a couple of hours, and her rings were getting tight. She thought something might be wrong. I told her that some swelling is normal in most pregnancies and that wearing tight-fitting clothing that restricts blood flow can produce a problem in blood return from the arms and legs. Sure enough, she said she had been wearing regular pantyhose. Clothing that is tight at the waist, knees, ankles, shoulders, elbows or wrists can all cause problems.

You may notice, especially as you near the end of pregnancy, that when you take your shoes off you may not be able to put them back on if you leave them off for a while. This problem is related to swelling.

You may also notice that wearing nylon stockings that are tight at the knee (or tight socks) leaves an indentation in your legs. It may look like you still have clothing on.

The way you sit can also affect circulation. Crossing your legs, either at the knee or at the ankle, restricts blood flow to your legs. To improve circulation, don't cross your legs.

Does Every Woman Need an Enema?

Many women want to know if their doctor performs routine procedures at the time of delivery. One such procedure is an enema.

In the past, many doctors and many hospitals gave enemas routinely, without giving you much choice in the matter. Having an enema early in labor has its benefits. It decreases the amount of contamination by bowel movement or feces at the time of delivery and during labor, resulting in infection. It may also help after delivery, if you have an episiotomy. You may be happy not to have a bowel movement for a while.

Ask your doctor if an enema is routine or considered helpful. Tell him or her you'd like to know about the benefits of an enema and the reason for giving an enema in early labor. It isn't required by all doctors or all hospitals.

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From Your Pregnancy Week by Week by Glade B. Curtis, M.D., OB/GYN. Copyright by Fisher Books. Electronic rights by Medical Data Exchange.

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