SECOND TRIMESTER

When do the postural changes of pregnancy occur?

Women experience a progressive increase in the anterior convex shape of the lumbar spine during pregnancy. This change, termed lordosis, helps keep the center of gravity stable and over the legs as the uterus enlarges (see below). Late in pregnancy, aching, weakness, and numbness of the arms may occur secondary to compensatory anterior positioning of the neck and hunching of the shoulders in positional response to exaggerated lordosis. These positional responses put traction on the ulnar and median nerves, resulting in the previously mentioned symptoms.

Relaxin in pregnancy is secreted by the corpus luteum, the placenta, and part of the decidual lining of the uterus. It is thought to cause remodeling of the connective tissue of the reproductive tract, especially inducing biochemical changes of the cervix. Although relaxin levels are more than 10-fold higher than nonpregnant levels, it is not currently thought that this hormone has a direct effect on actual ligamentous loosening. Joint laxity and shifting center of gravity can contribute to an increase in gait unsteadiness. These changes are most exaggerated in later pregnancy. More than 50% of gravid females complain of back pain during pregnancy, which may also be due to sacroiliac joint dysfunction or paraspinous muscle spasm.

About 4-6 per 1000 women will have scoliosis. This is not accompanied by any functional osteoporosis, although pregnancy is a very high bone turnover state, approximately equivalent to double the bone loss rates of a menopausal female, reversibly losing about 2% of bone during the first 20 weeks of gestation. Spinal changes are usually not severe enough to affect the pregnancy or the lung’s functional capacity. Also, the pregnancy rarely affects the degree of lateral curvature in these cases of scoliosis. If a pregnant patient has had correction with prior Harrington distraction rod insertion, the pregnancy, labor, and delivery are not typically affected. The epidural space may be distorted, and some anesthesiologists may refuse to place epidural anesthetics in these patients.

When do changes in the pelvic contour occur?

The pelvis continues to grow until about 3 years after menarche, which is why it is more common for younger women, and women sooner after menarche to have greater risk for obstructed labor due to the relative size discrepancy between the fetal head and the maternal pelvis. Relaxin was also thought to loosen pelvic ligaments when secreted from the ovaries, contributing to enlargement of the pelvis, but this is not proven in human pregnancies. The symphysis pubis can enlarge from about 3-4 mm in nulliparas to about 4.5 mm (or as much as 8 mm) in multiparas, but during gestation itself the average separation is about 7-8 mm.

When is fetal movement usually felt?

Most women feel the beginnings of fetal movement before 20 weeks’ gestation. In a first pregnancy, this can occur around 18 weeks’ gestation, and in following pregnancies it can occur as early as 15-16 weeks’ gestation. Early fetal movement is felt most commonly when the woman is sitting or lying quietly and concentrating on her body. It is usually described as a tickle or feathery feeling below the umbilical area. As the fetus grows in size, these feelings become stronger, regular, and easier to feel. The medical term for the point at which a woman feels the baby move is quickening. Babies should move at least 4 times an hour as they get larger, and some clinicians advise patients to count fetal movement to follow the baby’s well-being.

What kind of breast changes are normal during pregnancy?

Bumps that appear to enlarge around the areola are called Montgomery tubercles, and they normally appear during mid pregnancy.

obstetrics