Pregnancy is a biological state in which a female body nurtures the development of one or more offspring. It usually occurs in the uterus after the fertilization of an egg by a sperm, marking the beginning of a gestational process that typically lasts around nine months in humans. During pregnancy, the embryo or fetus grows and develops, receiving nourishment and oxygen through the placenta. This period is characterized by various physiological and hormonal changes in the mother's body, preparing it for childbirth. Pregnancy is a crucial phase in the reproductive cycle and is often divided into three trimesters, each with its own set of developmental milestones and maternal changes.