2 weeks 0.1 Not given 3 weeks 0.2 3 grains 4 weeks 0.3 Not given 5 weeks 0.5 Not given 6 weeks 0.7 Not given 7 weeks 0.9 Not given 8 weeks 1.5 4 drachms 3 months 3.0 2 ounces 4 months 6.0 5 ounces 5 months 9.0 10 ounces 6 months 12.0 1 pound 7 months 15.0 3 pounds 8 months 17.0 5 pounds 9 months 20.0 6 to 9 pounds Professor Clark holds that if at birth the infant weighs less than 5 pounds, it rarely thrives, though the records show that many infants weighing much less than this have lived and thrived. In very rare cases, infants have been known to weigh no more than one pound at birth, and to have still survived and thrived. And, on the other hand, many cases are known where infants were born, and thrived, who weighed more than twice the average weight. So, at the last, it is difficult to lay down hard and fast rules in the case. DELIVERY. At the termination of the period of gestation, the child is born into the world, and, instead of depending upon the blood of the mother for nourishment and oxygen, it begins to ingest its own food, to eliminate its own waste matter through the regular channels of the body, and to use its own lungs for the purpose of obtaining oxygen for its blood and to burn up the waste products in the lungs. The process of bringing a child into the world is called "parturition." The fetus is expelled from the body of the mother by the contraction of the muscles of and around the Uterus, and also by the contraction of the abdominal walls. In the early stages of labor, the uterine muscles are brought into play; but when the fetus enters into the vaginal passage the abdominal muscles manifest their energy. The uterine and abdominal muscular movements are purely involuntary, although the mother may aid in the delivery by voluntary muscular movements. The involuntary muscular movements are due to the reflex action originating, probably, in a part of the spinal cord. The uterine contractions are rhythmical, and have been compared to the contraction of the muscles of the heart. Each "labor pain" begins with a minimum of contraction, the activity increasing until a maximum is reached, when it gradually decreases, only to be followed a little later by a new contraction. When the fetus is finally expelled from the Uterus (followed later by the placenta or "afterbirth") that organ begins a gradual contraction to its normal size, shape, and condition, the restorative process usually lasting over several weeks. THE PHYSICAL SIGNS OF PREGNANCY. The physical signs of pregnancy in the case of women of normal health are as follows: