An estimated 50,000 women of childbearing age undergo inpatient bariatric surgery each year, and an unknown number have outpatient bariatric procedures, according to a report in the Journal of the American Medical Association.
Unfortunately, data about the surgery's effects on pregnancy, fertility, and contraception are still so limited that researchers are precluded from drawing firm conclusions and clinicians cannot make informed decisions regarding these patients, said Dr. Melinda A. Maggard of the Rand Corp., Santa Monica, Calif., and her associates.
The investigators used data from a national health care sample to assess trends in inpatient bariatric surgeries between 1998 and 2005, the most recent year for which information was available. This sample included data on up to 8 million hospitalizations at approximately 1,000 medical centers.
Outpatient bariatric surgeries were not assessed in this study.
The rate of inpatient bariatric procedures—laparoscopic adjustable gastric banding, vertical-banded gastroplasty, Roux-en-Y gastric bypass, and biliopancreatic diversion/duodenal switch—increased by 800% during this interval, from just more than 12,000 to more than 113,500 cases annually.
From 2003 to 2005, women of childbearing age (ages 18–45) accounted for around half of these surgeries (50,000) annually.
Dr. Maggard and her colleagues also reviewed 75 studies in the literature that compared ob.gyn. data between women who underwent bariatric surgery and those who did not.
“The available evidence suggests that risks for maternal complications, such as gestational diabetes and preeclampsia, may be lower following surgically induced weight loss than the risks in obese women, and may approach community rates,” they said (JAMA 2008;300:2286–96).
However, there have been 20 reports of complications during pregnancy that were directly related to the bariatric surgery, including bowel obstructions, band malfunctions, ulcers, and staple-line stricture. Three mothers and five neonates in these cases died.
Bariatric surgery doesn't appear to strongly influence the rate of cesarean deliveries or that of delivery complications such as blood loss or operative injury.
However, few studies have assessed such outcomes in this patient population, the researchers wrote.
Neonatal complications such as preterm delivery and low birth weight may be less common in pregnancies following bariatric surgery.
Similarly, neonatal outcomes such as macrosomia appear to be less frequent. However, the rate of miscarriage appears to be higher in women who have undergone bariatric surgery than in those who have not.
Moreover, two studies reported higher than expected rates of neural tube defects in neonates of women who had undergone bariatric surgery, possibly related to the mothers' noncompliance with vitamin supplementation.
Nutritional problems during these pregnancies seem to be uncommon and, like neural tube defects, are often attributed to the women's noncompliance with taking the recommended nutritional supplements.
Most studies of fertility after bariatric surgery were small and incomplete, the researchers reported. However, their results suggested that the procedures normalized hormone levels and menstrual irregularities, thus improving fertility.
Dr. Maggard and her associates also reported finding that no randomized trials have yet explored the theoretical possibility that bariatric surgery impairs absorption of oral contraceptives, rendering them less effective.
Risks for maternal complications may be lower following surgically induced weight loss. DR. MAGGARD