Published January 29, 2008 by
Beyond the newborn baby gifts, the fuss of having a new family member, and your tummy growing bigger, there will be changes happening that you may or may not be ready for. But it's always best to be prepared and knowledgeable.
The change from a microscopic cell to a seven pound baby requires substantial alterations in the body of the mother carrying the baby as well. However, while the baby changes most rapidly in the first few weeks, the mother undergoes her most dramatic changes in the later stages of pregnancy. In the first six weeks, the mother's physical changes are due primarily to alterations in hormone levels. These changes are subtle, and she may not even realize she is pregnant. She may have few symptoms or may easily attribute them to other causes. After this time, the mother's physical changes are partly dependent on the growth of the baby and become more noticeable as the baby gets larger and larger. Although the most obvious changes occur in the uterus and abdomen, almost all of the organs in her body are altered.
When a woman becomes pregnant, her uterus is the part of her body that is affected first and that undergoes the most significant changes. It increases to five or six times its original size, twenty times its original weight, and one thousand times its initial capacity. The amount of muscle, connective and elastic tissue, blood vessels, and nerves increases.
The shape changes from elongated to oval by the second month, to round by mid-gestation, then back through oval to elongate at term. The uterus softens beginning at the sixth week. It changes position as it increases in size, ascending into the abdomen by the fourth month and eventually reaching to the liver. It also becomes more contractile, with irregular, painless, Braxton-Hicks contractions beginning in the first trimester. These contractions may be felt in the last weeks of pregnancy, when they are known as false labor.
Other parts of the reproductive system change along with the uterus, the cervix and vagina have increased blood supply, which causes a darkening in color. This is apparent by the sixth week. The amount of the elastic tissue increases to prepare the way for the stretching that will be required during delivery. Secretions increase, and a mucous plug develops in the cervix. The fallopian tubes, ovaries, and ligaments supporting the uterus all enlarge and elongate. The ovaries, of course, cease to ovulate.
During the fourth month, the uterus will grow into the abdomen, causing the abdominal wall to expand to accommodate it. The connective and elastic tissues are stretched and straitened, creating thin areas called striae [stretch marks]. Unfortunately, while the color of the striae may fade, scars remain after delivery. In fifty percent of women, striae will develop in the third trimester. Late in pregnancy, the internal pressure from the large uterus may even cause the muscles of the abdominal wall to separate.
A woman's breasts must undergo many changes during pregnancy to be able to produce milk. In the first two months, the breasts may feel sore or full. They will increase in size, and veins may become visible on the surface. Striae can develop. The nipples also increase in size and usually darken in color. By mid-pregnancy, colostrums [a thick, yellowish fluid] can be expressed, but milk is not produced until after delivery.
Since the baby is being fed by the mother's blood supply and the mother's enlarging reproductive organs require more blood flow, the amount of blood must also increase. During pregnancy, blood volume expands by twenty-five to forty percent, but the number of red blood cells [the oxygen carrying component of blood] increases to a lesser extent. Therefore pregnant women are generally anemic-that is, their blood's oxygen-carrying ability is somewhat decreased.
To pump an increased amount of blood through the body, the heart must work slightly harder, the heart pumps more blood per beat and beats slightly faster. Heart murmurs attributed to the flow through the heart may develop.
The blood vessels are also affected by pregnancy. The enlarging uterus pressing on veins in the pelvis, increasing the pressure in the veins from the legs. The increased pressure causes the leg veins to enlarge producing varicosities [areas of enlargement]. It may also cause fluid to leak out of the veins and into the tissues, causing swelling of the feet and ankles. Late in pregnancy, the uterus can also compress a major vein, the vena cava, in some women when they lie on their backs; if this occurs, blood is prevented from returning to the heart and a feeling of faintness results.
The enlarging uterus not only pushes forward on the abdominal wall and down on the pelvic veins, but it also pushes up on the bottom of the rib cage and on the diaphragm [the muscle that stretches across the bottom of the chest cavity and assists in breathing]. The rib cage widens, and most women breathe slightly faster. Some feel short of breath.
Urination and digestion are also affected during pregnancy. The urinary tract is changed both by pressure from the uterus and by hormonal influences. The uterus presses against the bladder, which may cause a pregnant woman to urinate more frequently. Hormones cause the ureters [the tubes conducting urine from the kidneys to the bladder] to distend and the flow of urine in them to slow. The sluggish urine flow predisposes a pregnant woman to infection. Hormones, along with the increased blood volume, also causes the kidneys to filter more blood, however, the kidneys may not reabsorb sugar and protein efficiently because of this increased workload, and these substances may spill into the urine. Since the presence of sugar in the urine can also be caused by diabetes and the presence of protein can be caused by infection, most doctors screen the urine frequently during pregnancy and may do other tests if any abnormality is found.
The changes in digestion during pregnancy are well known and frequently kidded about. A pregnant woman craving for pickles and ice-cream has been the premise of many a joke. Women may have unusual cravings, and may also notice changes in the senses of smell and taste, which may cause them to alter eating habits. During pregnancy women often produce more saliva and the saliva will be more acidic, which promotes tooth decay. The gums are more sensitive and may bleed easily. In the first trimester, a woman may have morning sickness characterized by vomiting and a poor appetite. She may also be constipated. One of the pregnancy hormones causes the muscles of the digestive tract to relax, and they therefore pass digesting food more slowly through the intestines. In addition, the uterus can press on the colon, inhibiting passage of feces. Similar mechanisms produce heartburn. The muscles at the junction of the esophagus and the stomach relax and the uterus presses on the stomach from below, causing the stomach contents to flow back into the esophagus. In late pregnancy, the stomach may even be pushed up into the chest, producing a hiatal hernia.
A number of changes are necessary in the structures supporting the uterus to stabilize it as it grows. The ligaments in the pelvis and abdomen stretch to accommodate the uterus, in late pregnancy the upper part of the spine bends backward to compensate for the enlarging abdomen. Hormones loosen the joints of the pelvis in preparation for childbirth.
Hormonal influences are also responsible for changes in the skin. Pigmentation of the nipples, vulva [the external genital organs], the center of the lower part of the abdomen, and the umbilicus increases. Darkening across the face may appear; this is known as chloasma, or the mask of pregnancy. Hormones can also cause reddening of the palms and the appearance of small red spots on the skin; these are nests of blood vessels, which are known as spider nevi or telangiectasias. Sweat and all glands also become more productive.
One of the most important changes during pregnancy is the increase in metabolism, which is necessary to provide nourishment to the fetus .A woman must eat more in order to supply adequate protein, carbohydrates, and fat to the fetus and her own enlarging body. Most women gain about twenty-five pounds, three pounds in the first trimester, and ten to twelve pounds in each of the second and third trimesters. The placenta, fetus and amniotic fluid and the increased volume of blood and breast and urine tissue account for twenty pounds of that weight gain. The rest of the weight is fat and extra fluid. A pregnant woman must also take in more vitamins and minerals for the growing of the fetus. Calcium, which is needed for developing bones, and iron, which is used to make new blood cells, generally needs to be ingested in greater amounts from the fourth month of pregnancy on.
The physical changes during pregnancy are miraculous. Amazingly, though, the physical alterations in the mother reverse after birth, and her body returns to its normal state. For the new baby, however, the process of change that started nine months before has just begun.