4.2.2 THE WOMAN DURING PREGNANCY
Having summarized the development and growth of a new life before its birth, we now turn to the experience of the expectant mother.
The Signs of Pregnancy
The placenta, which develops in response to the implantation of an embryo, produces a certain hormone called chorionic gonadotropin. This hormone acts upon the ovaries, stimulating them to continue the production of the hormones estrogen and progesterone. As a result, no new eggs are released and no menstruation occurs since the uterine lining does not deteriorate but remains in its place for the duration of the pregnancy. (For details on the menstrual cycle, see "The Female Sex Organs.") For this reason, a woman who has had sexual intercourse usually suspects that she has become pregnant as soon as she misses her regular menstrual period. However, this sign alone is not conclusive because the menstruation may just be delayed for one reason or another (sometimes for quite a while). The likelihood of a pregnancy increases if she also experiences an enlargement of her breasts, a darkening of the area around the nipples, nausea (morning sickness), and a more frequent need to urinate. Still, all of these so-called presumptive signs of pregnancy do not mean definite proof.
A greater degree of certainty is provided by the so-called probable signs of pregnancy, such as an enlargement of the uterus, a softening of the cervix, and an enlargement of the abdomen sometime during the third month. Three weeks after implantation (or about six weeks after the last menstruation) the placental hormone chorionic gonadotropin can be detected in the woman's urine. Such a simple pregnancy test can be made within a few minutes in a laboratory or in a doctor's office. However, although a positive test (detecting the hormone) is almost always correct, a negative result (failing to detect the hormone) is not necessarily reliable.
There are three truly reliable signs of pregnancy: 1. the heartbeat of the fetus, which the doctor can hear through his stethoscope at about the beginning of the fifth month, 2. the active movement of the fetus, which can be felt at about the same time, and 3. the skeleton of the fetus, which will appear on an X-ray picture. (The exposure of fetuses to X rays is usually avoided for medical reasons.)
The First Trimester
Doctors divide the nine months of a pregnancy into three trimesters, i.e., three equal time periods each lasting three months. During the first trimester (dated from the first day of the last menstruation), the woman experiences the early signs of pregnancy. Thus, a lack of menstruation and morning sickness are usually sufficient reason to see the family doctor or an obstetrician. The doctor will try to determine whether a pregnancy has, in fact, occurred. As mentioned above, simple hormonal pregnancy tests are possible about six weeks after the last menstruation. If the pregnancy is confirmed, medical supervision and care should continue up to the time of delivery. The woman's medical history has to be taken, and a thorough physical examination has to determine whether any problems or complications should be expected. In addition, several tests have to be performed. For example, one blood test will find out whether the woman is Rh-positive or Rh-negative; another can detect syphilis. (For details, see "Possible Problems and Complications" and "Venereal Diseases.") All of these measures can contribute to a normal pregnancy and the birth of a healthy baby.
The Second Trimester
The time between the beginning of the fourth and the end of the sixth month is usually the most comfortable for the pregnant woman. The previous morning sickness disappears, and the fetus, being still rather small, does not cause any discomfort. However, sometime around the fifth month the fetal movements can be felt, and the fetal heartbeat can be heard without any elaborate equipment. As the fetus continues to grow, the abdomen begins to enlarge visibly until, toward the end of the second trimester, the pregnancy becomes quite apparent.
The Third Trimester
During the last three months of pregnancy, the woman has to visit her doctor more often because potential complications are most likely to occur during this period. The growth of the fetus becomes even more obvious as the swelling in the woman's abdomen reaches higher above the navel. By the thirty-eighth week of pregnancy, the fetus has attained its maximum growth and is then called term fetus. It is ready to be born.
The exact time from the beginning to the end of pregnancy varies, even with the same woman. Women who engage in vigorous physical exercise usually deliver sooner than others, girls are often born a little earlier than boys, and, in some very rare cases, pregnancies last over 280 days.
Possible Problems and Complications
In the course of a pregnancy, a woman's body changes in many ways. Some of these changes may be experienced as unsettling or unpleasant. For example, nausea, indigestion, constipation, backaches, cramps, and varicose veins are not uncommon in expectant mothers and may cause some concern. However, these complaints do not indicate serious problems in themselves, but are a normal part of childbearing. Nevertheless, there are some complications that require medical attention. A woman can forestall, alleviate, or at least prepare herself for most of these difficulties by regular visits to her doctor during her pregnancy.
Almost 25 percent of all pregnancies end with the death of the fetus during the first two trimesters, i.e., in spontaneous abortions or miscarriages. The reason is usually some abnormal development of the fetus caused by a defective egg or sperm, or by some difficulty in implantation. Other reasons are anatomical or functional abnormalities in the woman. The cause may also be found in a poor diet, an illness, or some psychological problem. Strenuous physical exercise as such has no harmful effect. Contrary to popular belief, jumping, falling, or being struck or kicked in the abdomen do not cause a woman to have a miscarriage.
A miscarriage during the last trimester is called stillbirth. However, the closer the normal date of delivery is at hand, the greater is the chance for survival of the fetus. It is possible (although quite rare) that a fetus born toward the end of the sixth month might survive. After seven months, the chance of survival is fairly good and increases even further during the eighth month. Naturally, in all of these cases expert care is important.
The causes of premature births are not always clear. It has been suggested that certain illnesses or other maternal problems might be responsible. Indeed, there is some evidence that heavy smoking on the part of the expectant mother may be a contributing factor.
The Rh Factor
The Rh factor (short for Rhesus factor) is an antigen present in the blood of most people. These people are therefore called Rh-positive. A problem arises when a woman with Rh-negative blood becomes pregnant by an Rh-positive man. In this case, the fetus may also be Rh-positive. The woman's body may react to this situation by producing antibodies which could harm the fetus. In the case of a first pregnancy, this is usually not much of a problem, although later pregnancies can be adversely affected. Still, such conditions can be controlled by modern medical measures.
Toxemia is a disease of pregnancy which produces symptoms such as high blood pressure, a sudden weight gain, swollen ankles, and protein in the urine. If it goes unchecked, toxemia can lead to dangerous convulsions (eclampsia), or to premature separation of the placenta. There is no complete agreement as to the cause of this disease. It seems, however, that a properly balanced diet can do much to prevent it.
There are some very rare cases where a woman who is not pregnant develops symptoms quite similar to those of pregnancy. She may stop menstruating for months and experience morning sickness, a weight gain, an enlargement of the abdomen, indeed even labor, and all this in spite of the fact that there is no fetus that could be delivered. Quite obviously, this condition can be recognized by the absence of reliable signs of pregnancy (fetal movements, fetal heartbeat, and fetal skeleton on an X-ray picture).