Labor that begins before the end of the 37th week is considered "preterm" or "premature." Approximately 1 out of every 10 babies born in the United States is born preterm. No one knows the exact cause of preterm labor, but certain situations increase the odds for it. Those include the following:
- Multiple pregnancy. About 97% of twin pregnancies, for instance, result in preterm labor.
- Problems with the placenta, such as placenta previa or placenta abruptio.
- Problems with the uterus, such as structural defects, an incompetent cervix, or fibroids.
- Infections in the cervix moving up into the uterus.
- Past preterm labor or delivery.
- Short intervals (less than a year) between pregnancies.
- Being younger than 18 or older than 40 during pregnancy.
- PPROM (Preterm Premature Rupture of Membranes).
Other possible culprits include vaginal infections, poor nutrition, stress, depression, smoking, and alcohol and drug abuse.
Warning signs for preterm labor include:
- More than five contractions an hour, or contractions that get longer, stronger, and closer together
- Abdominal cramps, pain, or pressure
- Lower back pain
- Spotting, bleeding, mucous, or watery discharge from your vagina
- Ruptured membranes (leaking a large amount of fluid from the vagina)
If you have any of those signs before Week 37, you should contact your health care provider.