Pregnancy is the period during which a baby is contained in its mother's uterus, or womb, before it is born. Human pregnancy lasts about nine months; during this time the baby grows from a tiny fertilized egg to a baby of about seven pounds.
First signs of pregnancy are cessation of menstruation, enlargement of the breast, and other bodily changes, and sometimes a kind of nausea called "morning sickness."
Pregnancy begins at conception when the sperm fertilizes the ovum. The fertilized ovum sends out little threadlike villi which attach themselves to the wall of the uterus and grow to become the fetal portion of the placenta. The placenta is a special structure of glands and blood vessels through which the baby receives nourishment.
By the end of the fourth month, the mother feels "signs of life," the restless movements of the baby, or fetus, and the doctor can distinguish the fetal heartbeat.
Pregnancy ends with labor, the process by which the baby is expelled from the uterus and given birth to or born.
