Fetus Length: 48 to 52 cm (crown to rump, 35 to 37 cm). Weight: 3,000 g (7 to 7.5 lb). Fetus kicks actively, hard enough to cause the mother considerable discomfort. Fetal hemoglobin begins its conversion to adult hemoglobin. The conversion is so rapid that, at birth, about 20% of hemoglobin will be adult in [...]

Fetus Length: 42 to 48 cm. Weight: 1,800 to 2,700 g (5 to 6 lb). Body stores of glycogen, iron, carbohydrate, and calcium are augmented. Additional amounts of subcutaneous fat are deposited. Sole of the foot has only one or two crisscross creases compared with the full crisscross pattern that will be evident at term. [...]

Fetus Length: 38 to 43 cm. Weight: 1,600 g. Subcutaneous fat begins to be deposited (the former stringy, “little old man” appearance is lost). Fetus is aware of sounds outside the mother’s body. Active Moro reflex is present. Birth position (vertex or breech) may be assumed. Iron stores that provide iron for the time during [...]

Fetus Length: 35 to 38 cm. Weight: 1,200 g. Lung alveoli begin to mature, and surfactant can be demonstrated in amniotic fluid. Testes begin to descend into the scrotal sac from the lower abdominal cavity. The blood vessels of the retina are extremely susceptible to damage from high oxygen concentrations (an important consideration when caring [...]

Fetus Length: 28 to 36 cm. Weight: 550 g. Passive antibody transfer from mother to fetus probably begins as early as the 20th week of gestation, certainly by the 24th week gestation. Infants born before antibody transfer has taken place have no natural immunity and need more than the usual protection against infectious disease in [...]

Fetus Length: 25 cm. Weight: 223 g. Spontaneous fetal movements can be sensed by the mother. Antibody production is possible. Hair forms, extending to include eyebrows and hair on the head. Meconium is present in the upper intestine. Brown fat, a special fat that will aid in temperature regulation at birth, begins to be formed [...]

Fetus Length: 10 to 17 cm. Weight: 55 to 120 g. Fetal heart sounds are audible with an ordinary stethoscope. Lanugo (the fine, downy hair on the back and arms of newborns, apparently serving as a source of insulation for body heat) is well formed. Liver and pancreas are functioning. Fetus actively swallows amniotic fluid, [...]

Fetus Length: 7 to 8 cm. Weight: 45 g. Nail beds are forming on fingers and toes. Spontaneous movements are possible, although usually too faint to be felt by the mother. Some reflexes, such as Babinski reflex, are present. Bone ossification centers are forming. Tooth buds are present. Sex is distinguishable by outward appearance. Kidney [...]