Prenatal care begins with the confirmation of pregnancy usually using a urine test that screens for elevated levels of the pregnancy hormone, HCG. A physical exam and blood testing may follow, as well as a doctor-patient interview about past pregnancies and family history. Often, routine check-ups to monitor the growth and health of the fetus and the mother continue once every four weeks for the first two trimesters and once every two weeks for the final trimester.
Obstetricians provide due dates as estimations only. Some children are born prior to their due date, and others are born after their due date. Few are born on their original estimated dates of arrival. In some cases, complications or pre-term labor can lead to an early delivery.