5 Things You Should Know About Preterm Labor

What Influences Preterm Labor?

Smoking
Toxins in cigarette smoke pass through the placenta and travel to the baby. When you smoke, you're sharing those toxic chemicals with your growing baby. Studies show that women who smoke have smaller babies and a higher incidence of preterm labor, placental abruption (premature separation of the placenta from the uterus), placenta previa (abnormal positioning of the placenta over the cervix) and perhaps premature rupture of the amniotic membranes.

Stress

One interesting association that has been reported by several studies is an association between psychological stress and preterm birth. The mechanism for this is not yet known. This is a risk factor that women usually can't control, but one that appears to increase the risk of preterm birth.

Maternal Age

The risk of delivering a low birth weight (LBW) infant is greatest at both extremes of a woman's reproductive life. There are many factors that influence this risk. For example, young teenagers often have poor eating habits, poor weight gain, neglect to take their vitamin supplements, and fail to seek prenatal care early in pregnancy. They may also smoke, drink alcohol, or use drugs. As women get older their chance of multiple gestation (twins, triplets, etc.) increases. Multiple gestation often ends with a preterm delivery and babies that are low birth weight. Older women are also more prone to hypertension, diabetes, heart conditions , and heart and kidney disease. These diseases can complicate a woman's pregnancy and make her more prone to preterm delivery.

Previous Preterm Delivery

Women who have delivered a premature baby have up to a 20 percent chance of having a subsequent premature delivery. If a woman has had two premature births, some researchers estimate that the risk is over 50 percent that a subsequent birth will be premature. The risk data from two landmark research studies on spontaneous and subsequent preterm births (1985 study by R.A. Carr and M.H. Hill, and the 1995 J. Kristensen study) are shown in the table below.

Risk of Premature Delivery