Pregnancy FAQs: November 2008

First Trimester

The first trimester includes the pre-embryonic period and encompasses weeks two through ten. You might wonder what happened to weeks one and two. Pregnancies are conventionally dated with reference to the woman's last menstrual period. That's because most women don't know when conception actually occurred, but they can usually remember the first day of their last period.

The due date is calculated by adding 280 days (40 weeks) to the date of the first day of the last menstrual period. Obstetricians and midwives don't actually do the addition, of course. They use a pregnancy wheel, a plastic or cardboard wheel that is designed to show the date 40 weeks from any date on the calendar. The due date is not absolute: Only 16 percent of babies are actually born on the due date. The vast majority of babies is born between 38 and 42 weeks.

During the first trimester, most of the action takes place on the inside, and what a lot of action there is. You don't automatically look pregnant, and initially you might not even feel pregnant. But you are very likely to develop a lot of symptoms that are the result of the pregnancy. That's because the developing placenta produces hormones that have a variety of effects on maternal organs. For example, during the first trimester, the placenta produces hormones that already begin acting on the breasts in preparation for breast-feeding. Increased breast growth occurs that can cause temporary breast tenderness. And everyone knows about pregnancy-induced nausea ("morning sickness"), but tiredness and weight gain are also very common. You may even notice that your hair looks better when you're pregnant. Because of the increased blood flow associated with pregnancy, hair grows faster and thicker. Unfortunately, after delivery things return to normal.

The baby undergoes its most complex and important stage of growth during the first trimester. In fact, a human being grows faster during this period than at any other time in pregnancy, childhood, or puberty. The fertilized egg divides repeatedly, and the resulting cells organize into the embryo and the placenta. By week 12, all external structures and internal organs have been formed. The embryo is easily recognizable as human and has begun moving freely within the amniotic sac. Over the next 28 weeks the fetus grows and the organ systems mature, but no new structures develop.

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Pregnancy Part-I

Congratulations! You're expecting a baby! You may be excited, surprised, nervous, or a bit of all three. Your thoughts skip ahead to the day you'll hold your new baby in your arms. You anticipate choosing baby furniture and planning your delivery. And, today, there are so many delivery options available, you can often plan the type of delivery that you would like to have. But before you jump ahead to the main event, there are a few decisions that you will need to make during your pregnancy.

This section covers the course of normal pregnancy, routine prenatal tests, and some advanced technology. How does your baby develop? What changes does your body undergo during pregnancy? Chapters 1, 2, and 3 are devoted to the basic facts and terms used in discussing pregnancy.

Why should you routinely visit your obstetrician or midwife? What will happen during these prenatal visits? Chapters 4 and 5 explain how your pregnancy will be monitored. You'll learn about the measurements and testing that occur during the visits to your obstetrician or midwife. The routine tests you'll take during your pregnancy are discussed, as well as more advanced tests that are used in the event that potential problems are detected. For example, Chapters 6 and 7 discuss alphafetoprotein (AFP) tests and amniocentesis. The AFP assay can detect abnormalities by measuring concentrations of certain hormones in the mother's blood. Amniocentesis is the process by which the fetal chromosomes are directly analyzed.

Fortunately, most pregnancies proceed without problems. However, it's good to be prepared if you should encounter difficulties. Chapters 8, 9, and 10 offer an in-depth discussion of common problems in pregnancy. These chapters also cover diagnosis and treatment.

Any type of medical test can be anxiety provoking, but when you understand the purpose and method of testing, you may worry less. During pregnancy, two types of tests can be performed. These are screening tests and diagnostic tests. Screening tests are ordered routinely. They have been designed to be used on a large population to detect the possible presence of problems. The results are analyzed by comparing your test value to that of everyone in the large population. If your results are significantly different than average, it is possible that you may be affected by the problem the screening test was designed to detect. If this is the case, a diagnostic test will be recommended to determine whether you are truly affected.

Screening tests are designed in such a way that they err on the side of over diagnosis rather than under diagnosis. This means many more women will be asked to take diagnostic tests than will ultimately be found to have the condition under consideration. This is deliberate because testing more people than necessary is a precaution against missing someone who needs treatment. In practical terms, it means you should not be alarmed if the results of any of your screening tests are abnormal. The odds are still high that no problem exists. Of course, asking a pregnant woman not to worry is like asking her not to breathe-it's practically impossible.

If your practitioner suspects a problem, he or she will order diagnostic tests. The results of these tests can actually constitute a diagnosis. Such tests include ultrasound, which allow a partial visualization of the developing baby, and amniocentesis. Blood tests for determining glucose concentration to rule out gestational diabetes (diabetes of pregnancy) are another example of a commonly administered diagnostic test.

You may wonder why you should even bother with any prenatal testing. After all, pregnancy is now widely thought to be virtually risk free for mother and baby. You may even hear some people say that pregnancy and childbirth are "natural events," implying that nothing can go wrong. It's important to remember, though, that pregnancy-related problems are "natural," too. In fact, up until this century, pregnancy was considered quite dangerous for both mother and baby. The difference now is that we monitor pregnant women very carefully for any pregnancy-related problems. And we are better able to deal with many of these problems very early, before they can cause harm either to the mother or the baby.

Next Chapter: First Trimester

Pregnancy Symptoms

Symptoms are very unreliable for determining pregnancy. Many symptoms that are associated with pregnancy, like sore breasts, bloating, and hunger are also pre-menstrual symptoms. Furthermore, most pregnancy symptoms do not start until 7 weeks of pregnancy or later. In fact, most women have no symptoms in early pregnancy.

The only symptom that is somewhat reliable is missing a period. Pregnancy is the most common reason for a woman who is sexually active to miss her period. However, it is not the only reason. Sometimes women are late or even miss a period, without any obvious cause. This is not a sign that something is wrong.

In addition, a small number of women will continue to have some bleeding on the day they expect their period, even though they are pregnant. It is usually different than a regular period (lighter flow, shorter duration), but many women interpret any bleeding as a period

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