First trimester pregnancy

Alternative names:

early pregnancy; first 3 months of pregnancy; pregnant

Definition:

The early stage of pregnancy from conception to 12 weeks gestation or about 14 weeks from the first day of the last normal menstrual period (LNMP).

Causes, incidence, and risk factors:

Pregnancy is a normal condition and, in most situations, should not be approached as a problem or disease. There are many conditions that can affect the risk status of any pregnancy. Pregnancy at an extremely young age (less than 17 years old) is considered high risk because of increased medical risk to both the mother and baby and because of associated long-term psychological, social, and economic problems. (See teenage pregnancy).

A pregnancy begins with conception, when a sperm from a fertile male joins with an ovum (egg) of a fertile female. There were 3, 915,000 live births in the United States in 1996. The total number of pregnancies is difficult to estimate because some pregnancies end early by spontaneous abortion (miscarriage), which may occur before pregnancy is even suspected or confirmed. Any fertile female engaged in a sexual relationship with a fertile male is at risk of becoming pregnant.