Pregnancy is the period during which a fertilized egg develops into a fetus within a woman's uterus, typically lasting about 40 weeks from the first day of the last menstrual period to childbirth. It begins with conception, when a sperm fertilizes an egg during ovulation. The fertilized egg then travels down the fallopian tube and implants into the uterine wall, where it starts to grow. Pregnancy is divided into three trimesters, each marked by significant developmental milestones for the fetus and physiological changes for the mother. In the first trimester, the major organs and structures begin to form. The second trimester is characterized by continued growth and development, with the fetus becoming more active. The third trimester involves rapid weight gain and maturation of the fetal organs in preparation for birth. Pregnant women experience a range of physical and emotional changes, such as nausea, fatigue, hormonal fluctuations, and increased emotional sensitivity. Regular prenatal care is crucial to monitor the health of both the mother and the fetus, manage any complications, and prepare for a healthy delivery.