Addendum Continued
Pre-Labor Readiness
Labor generally occurs between the 38th and 42nd weeks of pregnancy when the fetus has reached maximum intrauterine development. Labor is preceded by a series of complex physiological changes in the placenta, uterus, fetus and mother working in synchrony, and ultimately leading to the birth of the baby. During the last several weeks of gestation, fetal development is focused on preparing the infant for independent external life and in inducing changes that contribute to the onset of labor. Following is a synopsis of these changes:
- The fetus gains weight at a more accelerated rate.
- The fetus stores iron at a rapid rate, storing enough to meet its needs for the first 4-6 months of extra-uterine life.
- Fetal temperature regulating mechanisms are developed.
- The placental membranes become more permeable and allow maternal antibodies to cross to the fetus. These antibodies provide immunity for the newborn from some diseases during its first several months of life.
- The fetal adrenal glands begin secreting steroid hormones which are essential for lung maturation.
- The fetus begins producing oxytocin and prostaglandins, labor stimulating hormones, which pass from the fetus to the maternal circulation.
- The fetus may become more or less active prior to the onset of labor.
- The placenta begins to age in late pregnancy which may be a factor in the onset of labor.
- The placental membrane increases its permeability to allow for the transfer of oxytocin and prostaglandins from the baby to the mother.
- Maternal breasts increase their production of colostrum, the thin yellowish first milk. Colostrum provides antibodies, carbohydrates, fats and a high level of protein to the infant. It also has a laxative effect to cleanse the baby’s intestinal tract of mucous and meconium after birth.
- Lightening, or engagement, is the process by which the fetus moves deeper into the pelvis. Relaxation of the pelvic ligaments, as well as a softening of the lower uterine segment due to hormonal influences, allows more room for the fetus to move down. Lightening may occur 10 days to 4 weeks prior to the onset of labor in the primipara (first time mother), and just prior to labor or in labor in the multipara (woman expecting her second or subsequent baby).
- Shortness of breath and heartburn improve when lightening occurs as there is now decreased pressure on the lungs, diaphragm and stomach.
- When lightening occurs there is less room for bladder expansion causing more frequent urination due to the additional pressures within the pelvis.
- Due to congestion of the vaginal mucous membranes from increased pelvic pressure, there is an increase in vaginal secretions.
- With the increased weight of the uterus pulling on the uterine ligaments attached to the lower back, there is an increased incidence of backaches.
- Changing estrogen and progesterone levels affect maternal fluid balance causing the mother’s weight to either stabilize or to drop from 1-3 pounds.
- Many women experience a “spurt of energy” approximately 24 hours prior to the onset of labor. It is thought that the spurt of energy is nature’s way of providing extra energy for the labor, although the etiology of this phenomenon is unknown. This energy should be saved for labor and not be expended on cleaning the house or other chores.
- Some women experience a “nesting instinct”. This is when the pregnant woman becomes totally absorbed in getting everything ready for the baby, arranging the nursery, checking and rechecking that everything is just right.
- Many women experience frequent soft bowel movements which are hormonally induced to clear the lower intestinal tract. This allows more room for the baby to move down. Diarrhea-like symptoms may be subtle signs of early labor.
Next: Addendum Continued
Final Step: Course Exam
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