Can bariatric surgery reduce obesity-related pregnancy risks?
Bariatric surgery can reduce the risk of diabetes and the likelihood of delivering overly large infants, according to a new Swedish study published in the New England Journal of Medicine. Conversely, women who had the weight-loss surgery were found to be more likely to have shorter pregnancies and deliver smaller-than-normal infants. Additionally, they had a possibly increased risk of stillbirth and neonatal death. Lead researcher Kari Johansson of Stockholm’s Karolinska Institute concluded that bariatric surgery “has both positive and negative influences on the risk of complications during a subsequent pregnancy.” She added in an e-mail to Reuters that the relationship between weight-loss and pregnancy outcomes is not necessarily one of cause-and-effect.
The study involved approximately 3,000 Swedish pregnancies between the years of 2006 and 2011, of which 596 included women who had bariatric surgery within the previous 5 years, and 2356 in which the women’s pre-pregnancy weight was similar to what the bariatric surgery patients had weighed prior to their procedure. About 2% of women in the surgery group developed gestational diabetes and 9% delivered overly large babies, as opposed to 7% and 22% respectively in the non-surgery group. On the other hand, 16% of women in the surgery group delivered smaller-than-normal babies and had pregnancies lasting 273 days, compared to 8% and 278 days respectively in the non-surgery group. Both durations fall within normal range.
The researchers found no difference in early labor or birth defect risks between the groups – though Johansson remarked that “we cannot exclude the possibility that risk of specific malformations differed between the two groups”. However, they did find that about 2% of post-bariatric surgery pregnancies ended in stillbirths or death of the baby in the first month of life. By way of comparison, this occurred only in 1% of pregnancies in women who didn’t have weight-loss surgery. “We therefore do not have a large enough sample to give any clear answer about this (whether higher risk of stillbirth or infant death was simply due to chance),” Johansson said. “This outcome needs to be studied further in even larger samples of patients.” The researchers say there isn’t enough data on pregnancy after bariatric surgery.
Dr. Aaron Caughey of Oregon Health and Science University in Portland wrote in an accompanying editorial that though preconception weight-loss surgery can potentially decrease some pregnancy risks, the American College of Obstetricians and Gynecologists recommends women to delay conception for 12-24 months – the period of most rapid weight loss – following surgery. He added that the type of surgery also plays a part. “In particular, those who have undergone the traditional Roux-en-Y gastric bypass surgery are at increased risk for protein, iron, vitamin B12, vitamin D, and calcium deficiencies; screening for these deficiencies is recommended by the [American College of Obstetricians and Gynecologists],” Caughey wrote.
High-risk pregnancy expert at the University of Rochester Medical Center in New York Dr. Loralei Thornburg - who was not involved in the study – agreed that “we have to interpret the findings with caution for different types of surgeries.” Both Caughey and Thornburg emphasized that pre-pregnancy bariatric surgery must be talked and thought about. “You should absolutely talk to your doctor. Everyone should strive to be at a healthy weight and in a healthy lifestyle before they enter pregnancy,” said the latter, while the former wrote that “decisions regarding bariatric surgery in women of reproductive age should take into account the benefits and risks of this not inconsequential procedure in terms of both pregnancy and long-term risk.” Obese women are known to have more complications during pregnancy. Bariatric surgery decreases stomach size and may bypass part of the digestive tract.