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During the third trimester, the expectant mother’s uterus expands to a level just below her breast bone. Crowding by the uterus, in addition to high levels of progesterone, may give the expectant mother heartburn and indigestion. She may also experience shortness of breath as her uterus presses upward on her diaphragm and ribs. Varicose veins in the legs, hemorrhoids, and swollen ankles sometimes appear because of the increased pressure within the abdomen, the decreased blood return from the lower limbs, and the effect of progesterone, which relaxes the walls of the blood vessels.
By the ninth month, the expectant mother often looks forward to the end of the pregnancy, relief from physical restrictions, and the long-awaited joy of having the baby. She may become more introspective and, at times, worry about labor, birth, and the baby. Through childbirth classes, the expectant couple can learn more about labor,
birth, and how to cope with the stress of the latter part of pregnancy.
In the third trimester of pregnancy, the expectant couple may feel protective of the developing baby. Adjustments in sexual activity continue as the expectant mother’s abdomen enlarges. Lines of communication should be open between the expectant mother and her partner about their needs, feelings, and desires.
About two weeks before the baby’s birth, the expectant mother’s profile may change as the fetus descends into the pelvic cavity. The expectant mother may now feel less pressure on her diaphragm and thus find it easier to breathe and eat. However, because the head of the fetus can press on the expectant mother’s bladder, she may need to
urinate more frequently.
In the beginning of the third trimester, around twenty-eight weeks, the fetus is about fourteen to seventeen inches long. It weighs about two and a half to three pounds. It is adding body fat at this time. Also, the fetus is very active. Rudimentary breathing movements are present.
At around thirty-two weeks, the fetus has grown to about sixteen and a half to eighteen inches long. It weighs about four to five pounds. The fetus has periods of sleep and wakefulness. It responds to sounds and may assume birth position. Bones of the head are soft and flexible at this time. Iron is being stored in the liver as well.
By the end of the third trimester, anywhere from thirty-six to thirty-eight weeks, the fetus has grown to nineteen inches long and weighs around six pounds. The skin is less wrinkled at this time. The vernix caseoa, the protective
coating of the skin, is thick. The lanugo, the downy hair that covered the body in the beginning of the second trimester, is mostly gone. The fetus itself is less active and it is gaining immunities from the mother as well.
Toward the end of the pregnancy, noticeable contraction of the uterus, called Braxton Hicks contractions, increase in frequency. These contractions, which have occurred intermittently throughout pregnancy and which may or
may not be felt by the expectant mother, help increase the efficiency of uterine circulation. Though usually not directly associated with labor, these contractions prepare the uterine muscles for labor.
As the pregnancy comes to an end and the baby’s head presses against the expectant mother’s pelvis, her cervix becomes stronger and thinner. This thinning is a sign of readiness for labor and birth.
Awkwardness and fatigue may add to the expectant mother’s motivation for the pregnancy to end. She may feel as if she has been and will be pregnant forever. At the same time, the expectant mother may feel a “nesting urge” in the form of a spurt of energy that often results in preparation for the arrival of the new baby. She now visits her
physician or midwife more often as the physical changes signal that her body is preparing for labor and birth.
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