Labor that occurs before 37 weeks of pregnancy is considered preterm.
What causes preterm labor is not well understood. However, certain conditions may make it more likely:
A healthy lifestyle during pregnancy can help reduce the risk of preterm labor, as can regular visits to the doctor or midwife, who can then identify potential problems early.
Because babies born prematurely can have serious health problems (see see Prematurity), doctors try to prevent or stop labor that begins before the 34th week of pregnancy. Preterm labor is difficult to stop. If vaginal bleeding occurs or the membranes rupture, allowing labor to continue is often best. If vaginal bleeding does not occur and the membranes are not leaking amniotic fluid (the fluid that surrounds the fetus in the uterus), the woman is advised to rest and to limit her activities as much as possible, preferably to sedentary ones. She is given fluids and may be given drugs that can slow labor. These measures can often delay labor for a brief time.
Samples may be taken from the cervix, vagina, and anus to culture. Analysis of these samples may suggest a specific infection as the cause of preterm labor.
Drugs that can slow labor include the following:
Women are given antibiotics until culture results are obtained. If results are negative, the antibiotics are then stopped.
If the cervix opens (dilates) more than 2 inches (5 centimeters), labor usually continues until the baby is born. If doctors think that premature delivery is inevitable, a woman may be given a corticosteroid such as betamethasone. The corticosteroid helps the fetus's lungs and other organs mature more quickly and reduces the risk that after birth, the baby will have difficulty breathing (neonatal respiratory distress syndrome) or other problems related to prematurity.
Last full review/revision June 2013 by Julie S. Moldenhauer, MD