Pregnancy Health Article

Fourth month

Growth is very rapid during this period, and limb movements become coordinated, although it is difficult for the mother to feel them. An ultrasound reveals the bones of the fetal skeleton, which are clearly visible. Their development continues as the limbs lengthen. Scalp hair patterning is also determined during this period, and slow eye movements can occur at about 14 weeks. External genitals can be recognized by 14 weeks, and the external ears stand out from the head. The fetus is now about 6 inches (15 cm) long, and weighs about 4 ounces (112 g).

Fifth month

"Quickening" is the mother's feeling the baby move for the first time; it usually occurs during this period. The average time between a mother's first detection of fetal movements and delivery is 147 days, with a deviation between plus or minus 15 days. The baby's skin is now covered with a greasy, cheese-like material called "vernix caseosa," and it protects the delicate fetal skin from cuts, chapping, and hardening, all of which could occur from exposure to the amniotic fluid. Eyebrows and head hair are also visible at 20 weeks, and the fetus is usually completely covered with fine, downy hair (the lanugo), which helps to hold the vernix on the skin. Brown fat forms during this period to prepare for heat production when the baby is born. By 18 weeks, a female fetus has a formed uterus, and the opening for the vagina has begun. Many egg-forming follicles are also forming in the ovaries. By 20 weeks in a male fetus, the testes have begun to descend, but they are still located inside the abdominal wall. The fetus now weighs about one pound (454 g) and is 10 inches (25 cm) long.

Sixth month

There is a substantial weight gain this month. The skin, usually wrinkled, appears clear, and is pink to red because blood is visible in the capillaries. At 21 weeks, rapid eye movements (REMs) begin, and blink-startle responses are visible on ultrasound following a loud noise. Fingernails are present by 24 weeks, and the cells in the lung have begun to secrete a substance necessary to develop the alveoli of the lungs. In most medical practices, a fetus born before 24 weeks is not considered viable or capable of living, but if born at 24 weeks, attempts will be made for survival. The chances of a good outcome are, however, very poor. The fetus now weighs

about 1.5 pounds (730 g), and is about 13 inches (32 cm) long.