What Are the Causes of Premature Contractions in Pregnancy?

According to Sutter Health, some women have Braxton-Hicks contractions during their pregnancy; a Braxton-Hicks contraction is an irregular, non-painful tightening of the uterine layers. However, if a woman is having painful contractions every 10 to 12 minutes before 37 weeks into her pregnancy, these could be premature labor contractions. The American Pregnancy Association reports that strong contractions can cause the cervix to open and lead to premature labor. Certain women may be predisposed to premature contractions.

Risk Factors

Certain conditions regarding a woman's pregnancy can predispose her to premature contractions. According to the American Pregnancy Association, women who are pregnant with multiple children, have had previous premature births, gave birth six to nine months before becoming pregnant again, or are carrying only one fetus after undergoing in vitro fertilization are more likely to have premature contractions.

Medical Causes

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According to the American Pregnancy Association, some medical conditions can cause premature contractions in pregnant women. These include certain uterine or cervical abnormalities, recurring bladder and kidney infections, urinary tract infections, vaginal infections, sexually transmitted disease and infections with fevers above 101 degrees F. Unexplained vaginal bleeding that occurs after the first 20 weeks of pregnancy can also result in premature contractions. Other medical conditions that can cause premature contractions include high blood pressure, kidney disease and clotting disorders. According to Sutter Health, women who have had multiple first trimester abortions or one or more second trimester abortions also have an increased risk of having premature contractions.

Lifestyle Causes

In addition to the medical causes of premature contractions, certain lifestyle changes can also cause premature contractions in pregnant women. Women who receive little or no prenatal care, work long hours while standing, smoke, drink alcohol, use illicit drugs, live with domestic violence or high levels of stress, or do not have social support are more likely to experience premature contractions.