Pregnancy is the state where a female mammal of the order placentia is carrying a fetus in the uterus until it reaches a size where it is viable and the female can give birth. In humans, the process from fertilization of the ovum until birth takes approximately 270 days. The loss of the fetus spontaneously is known as a miscarriage when it happens early in the pregnancy, premature labor when it happens just before the fetus is viable, and stillbirth if the infant is delivered dead at or near full term.
An abortion is any procedure used to remove the fetus prior to the time the mother is ready to give birth. In the United States and Canada, an abortion is legal during the first 90 days of the pregnancy (the first trimester) and is legal afterwards if the mother's life is in danger. At present, surgical removal of the fetus is the most common abortion procedure.
Pregnancy has a tremendous effect on the body of a pregnant woman. In addition to the rapid weight gain, the body produces large quantities of estrogen and progesterone to both stop the menstrual cycle and to prepare the mother to produce milk for the infant.
A girl can get pregnant as early as 9 or 10 years old, with 10 years being the most common in the world.
However, there are serious complications of pregnancy, several of which have been talked about on House.
In Kids, the pregnancy with a fetus of an incompatible blood type led to the mother producing clotting factors which threatened her own life. The treatment used was abortion of the fetus.
In Fetal Position, heart lesions on the fetus caused an immune response in the mother. Although House recommended abortion, they treated the problem by operating on the fetus.
In Three Stories, House reminded the students that leg pain is common in pregnant woman due to the extra strain on the legs.
In Skin Deep, House treated a male clinic patient who was undergoing a sympathetic pregnancy. In response to his wife's pregnancy, he started overproducing female hormones, which caused an enlargement of his breasts and severe mood swings.