medwireNews: Women who have had bariatric surgery are more than twice as likely to have a small for gestational age (SGA) baby than women who have not, Danish research shows.
Women who had undergone weight loss surgery also had a lower risk for large for gestational age (LGA) births, even compared with women with the same body mass index (BMI) who had not had surgery.
The study included 339 women who had singleton births after undergoing bariatric surgery between 2004 and 2010, matched to 1277 controls by pre-pregnancy BMI, age, parity, and date of birth. The majority (83.4%) underwent Roux-en-Y gastric bypass and the remainder underwent gastric banding.
Mette Kjær (Hvidore University Hospital, Denmark) and colleagues found that women who had undergone weight loss surgery had a 69% reduced odds for LGA compared with controls (2.4 vs 7.3%).
Meanwhile, the odds for SGA were increased 2.29-fold (7.1 vs 2.9% in control group) with the average birth weight being significantly lower among post-surgery women at 3312 g compared with 3585 g among controls.
The authors also found that the effect of surgery on birthweight was even greater among the subgroup of 268 women who underwent gastric bypass leading to a 2.78-fold increase in the odds for SGA compared with controls (7.7 vs 2.8%). This indicates that malabsorption rather than weight loss alone affects the baby during gestation, say Kjær and colleagues.
The authors say that previous studies have produced conflicting results about the risk for SGA after bariatric surgery, which may have been due to unmatched control groups, and failure to account for the fact that many people remain overweight or obese following surgery. This is the first nationwide study to confirm that post-bariatric surgery mothers are at risk for SGA, they add.
"Special obstetrical attention on maternal deficiencies and fetal growth restriction during pregnancy should be offered to women with prior bariatric surgery," they conclude.
By Kirsty Oswald, medwireNews Reporter