We are talking about Pregnancy which is a time that occurs when a sperm fertilizes an egg after it's released from the ovary during ovulation. Pregnancy is the term used to describe the period in which a fetus develops inside a woman's womb or uterus. Pregnancy usually lasts about 40 weeks, or just over 9 months, as measured from the last menstrual period to delivery. Health care providers refer to three segments of pregnancy, called trimesters.