"Pregnancy is the term used to describe when a woman has a growing fetus inside of her. In most cases, the fetus grows in the uterus. Human pregnancy lasts about 40 weeks, or just more than 9 months, from the start of the last menstrual period to childbirth. Prenatal care is the care a woman gets during pregnancy. Early and regular prenatal care is important for the health of both mother and developing baby. Health care providers also recommend preconception care before a woman considers becoming pregnant or between pregnancies. A missed period is often the first clue that a woman might be pregnant. Symptoms such as headache, fatigue, and breast tenderness can occur even before a missed period. Home pregnancy tests are inexpensive, private, and easy to use. They detect human chorionic gonadotropin, or hCG, in urine. hCG is made when a fertilized egg implants in the uterus and builds up in the body as pregnancy continues. Home pregnancy tests are highly accurate, but accuracy depends on when and how they are used, the person using the test, and the brand. The amount of hCG in urine increases with time, so testing too soon after a missed period can produce a negative result even when a woman is pregnant. Waiting one week after a missed period usually gives a more accurate result, and a test can be repeated after a week. If two tests are negative but pregnancy is still suspected, a doctor should be contacted. Test directions should be followed exactly, including checking the expiration date and waiting the recommended amount of time. Testing urine first thing in the morning may improve accuracy. A plus sign, color change, line, or the words “pregnant” or “not pregnant” may show the result. A control indicator shows whether the test is working; if it does not appear, the result should not be relied upon. Some medicines can affect home pregnancy tests, and different brands vary in how early they detect hCG. If a home pregnancy test says a woman is pregnant, she should call her doctor. A doctor can use a more sensitive test and a pelvic exam to confirm pregnancy. Early medical care can help the woman and baby stay healthy."