During childbirth, the muscles at the top of your uterus press down on the baby's bottom. Your baby's head then presses on your cervix which, along with the release of the hormone oxytocin (see 'How hormones help you give birth', below), brings on contractions.

What is delivering a baby called?

An obstetrician specializes in obstetrics, which deals with all aspects of pregnancy, from prenatal care to post-natal care. An obstetrician delivers babies, whereas a gynecologist does not. An obstetrician can also provide therapies to help you get pregnant, such as fertility treatments.

What happens during labor?

During active labor, your cervix will dilate from 6 centimeters (cm) to 10 cm. Your contractions will become stronger, closer together and regular. Your legs might cramp, and you might feel nauseated. You might feel your water break — if it hasn't already — and experience increasing pressure in your back.