November 18 (HealthDay News) -- Women who get pregnant after having weight-loss surgery have a lower risk of maternal and newborn complications than pregnant women who are obese, according to U.S. researchers who analyzed 75 studies.

Data from those studies showed that bariatric surgery in the United States increased by 800 percent between 1998 and 2005 (from 12,480 to 113,500). Women accounted for 83 percent of procedures among patients ages 18 to 45. Between 2003 and 2005, more than 50,000 women in this age group had inpatient bariatric surgery each year, which accounted for 49 percent of all bariatric surgeries.

The review authors found that pregnant women who'd had bariatric surgery had lower maternal complication rates than obese women, including gestational diabetes (0 percent vs. 22.1 percent) and preeclampsia (0 percent vs. 3.1 percent). In addition, maternal weight gain was reduced in women who'd had bariatric surgery.

Newborn outcomes among women who'd had laparoscopic adjustable band surgery were similar or better than outcomes among obese women: premature delivery, 7.7 percent vs. 7.1 percent; low birth weight, 7.7 percent vs. 10.6 percent; overly large body (macrosomia), 7.7 percent vs. 14.6 percent.

The findings were published in the Nov. 19 issue of the Journal of the American Medical Association.

"Research is needed to better delineate the extent to which surgery and subsequent weight loss improve fertility and pregnancy outcomes," the review authors wrote. "Optimizing success for contraception and producing healthy neonates following surgery will require a multidisciplinary effort by surgeons, primary care physicians, reproductive fertility specialists, obstetricians, and patients."

Having bariatric surgery during childbearing years may change a woman's fertility following weight loss, alter nutritional requirements during pregnancy, or impact contraception, the researchers noted.

SOURCE: Journal of the American Medical Association, news release, Nov. 18, 2008