Premature labor is defined as contractions that begin prior to 37 weeks of gestation. In certain situations, doctors may plan a pre-term birth to protect the mother’s or baby’s health – for example, if preeclampsia is detected. Otherwise, certain measures may be taken to try and prevent premature labor from continuing, so that the fetus can continue to develop in the womb as long as possible. With or without such measures, up to half of all women who experience premature labor end up having their babies delivered at the 37-week mark or later. While pre-term labor can occur in any pregnancy, potential contributing factors may include smoking during pregnancy, high blood pressure, stress, being underweight or overweight during pregnancy, multiple-birth pregnancies and a personal history of pre-term labor.