Pregnancy is the condition in which a woman carries a developing embryo or fetus. This state can be indicated by a positive over-the-counter urine test and confirmed through further methods like blood tests, ultrasounds, or detecting a fetal heartbeat. Typically lasting around nine months from the date of the woman's last menstrual period, pregnancy is divided into three trimesters, each approximately three months long.During the first trimester, crucial fetal cell differentiation occurs. Any damage to the fetus at this stage may lead to miscarriage or significant disability. A fetus in the first trimester is unlikely to survive outside the womb, even with advanced medical support, due to its underdeveloped systems. This phase concludes with quickening, when the mother first feels fetal movement. Some women may experience "morning sickness" during this time, which is a type of nausea that typically resolves within an hour of waking. Additionally, breast changes may occur as they prepare for nursing, causing discomfort from the hardening of milk glands. As pregnancy advances, the mother might notice various physical and emotional changes, such as mood swings or skin darkening in certain areas.In the second trimester, the fetus undergoes significant development, with its features becoming more distinct and functional. A prematurely born fetus during this period has some chance of survival, although there may be developmental challenges. As the fetus grows, the mother's pregnancy becomes more evident.The third trimester marks the final preparation for birth, with rapid weight gain for both the mother and fetus. As pregnancy approaches its end, the mother may experience discomfort as the fetus moves into position in her lower abdomen. Swelling of the ankles, balance issues, and other discomforts may occur. Despite these, many women continue their regular activities, including non-impact exercise and work, until the last weeks of pregnancy. Some may feel too uncomfortable to maintain their usual pace, while others experience a surge of energy just before labor begins. Pregnancy concludes when labor starts.For further information, see topics like acute fatty liver of pregnancy, fetal alcohol syndrome, fetal alcohol effects, tubal pregnancy, and prenatal care.