Maternal weight linked to risk of preterm delivery

NEW YORK, Apr 7 (Reuters) Women who gain very little weight or a lot of weight during pregnancy have an increased risk of having a preterm delivery, regardless of their weight before pregnancy, new research shows.

Dr Patricia M Dietz of the Centers for Disease Control and Prevention, Atlanta, and colleagues examined the effects of pregnancy weight gain on preterm delivery. They used data from the Pregnancy Risk Assessment Monitoring System, collected in 21 states, which included 113,802 women who delivered a single baby between 1996 and 2001.

The authors report in the journal Epidemiology that 8.7 percent of the women delivered a preterm infant. Before pregnancy, 16 per cent of women were classified as underweight, and 29 per cent as overweight, obese, or very obese.

All women with very low weight gain were at increased risk for preterm delivery; however, as pre-pregnancy weight increased, the odds decreased, Dietz and colleagues report. The odds of preterm delivery were highest among underweight women and lowest for very obese women.

Women who had high weight gain during pregnancy also had a substantially increased risk of preterm delivery, regardless of pre-pregnancy weight.

Although the strength of the association between excessive weight gain and premature delivery was not as strong as the association for low weight gain, excessive weight gain affects a much greater proportion of the population and deserves further study, the researchers point out.

Also, it is not clear if maternal weight actually causes preterm delivery, or if nutritional intervention could reduce preterm births, they add.

REUTERS KD ND1002