Pregnancy  is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of afemale. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets. Human pregnancy is the most studied of all mammalian pregnancies. Obstetrics is the surgical field that studies and cares for high risk pregnancy.Midwifery is the non-surgical field that cares for pregnancy and pregnant women.

Childbirth usually occurs about 38 weeks after fertilization(conception), i.e., approximately 40 weeks from the last normal menstrual period (LNMP) in humans. The date of delivery is considered normal medically if it falls within two weeks of the calculated date. The calculation of this date involves the assumption of a regular 28-day period. Thus, pregnancy lasts almost nine months.

The exact definition of the English word “pregnancy” is a subject of political controversy, but it is not a matter of substantial controversy in the medical community.