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About 3% of all pregnant women will give birth to twins, which is an increase in rate of nearly 60% since the early 1980s.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
Hyperthyroidism leads to an increased rate of metabolism and affects about 1% of women but only 0.1% of men. For most people, this increased metabolic rate causes the thyroid gland to become enlarged (known as a goiter).
Approximately 500,000 babies are born each year in the United States to teenage mothers.