Preterm labor is when preterm contractions cause the opening of the cervix before 37 weeks of pregnancy have elapsed. Should the contractions lead to labor, the baby will be born prematurely, which increases the health risks to the baby. A variety of risk factors may lead to preterm labor, but it may also occur with no known risk factors. 

Signs of preterm labor include regular painful contractions, a dull backache, a feeling of pressure on the lower abdomen, mild abdominal cramps, vaginal spotting or bleeding, vaginal discharge, and diarrhea. 

Among the risk factors for preterm labor are a history of giving birth early; pregnancy with multiple fetuses; stress; smoking cigarettes; substance abuse; cervical, uterine or placenta problems; infection, being overweight or underweight; a birth defect in the fetus; lack of prenatal care; and anemia. 

To minimize the chance of preterm labor, there are a number of preventative measures that can be taken, such as eating a healthy diet, leaving time between pregnancies, regular prenatal care, and stopping smoking. The progestogen Makena (hydroxyprogesterone) may also be prescribed by a physician.