Obese women who have weight-loss surgery between pregnancies may be less likely to experience complications like high blood pressure and preterm births in their second pregnancy, a recent study suggests. Researchers examined hospital records from 2002 to 2014 for more than 1.6 million women 15 to 45 years old in New South Wales, Australia. The study focused on 326 women who had bariatric surgery between their first and second pregnancies and 461,917 women who had two pregnancies without a weight-loss operation in between. The study found that for obese women who had the surgery between pregnancies, the risk of complications dropped markedly from the first pregnancy to the second, although it didn’t reach the level seen in the general population of women. “The odds of adverse pregnancy outcomes among women who have bariatric surgery do not decrease to the level observed in the general birthing population; however, there was substantial improvement,” lead study author Dr I Ibiebele of Royal North Shore Hospital in New South Wales and colleagues write in BJOG. “Although body mass index (BMI) was not directly assessed in this study, bariatric surgery performed for the management of obesity, in accordance with current clinical criteria, is likely to result in improved pregnancy outcomes in women who have a subsequent pregnancy,” Ibiebele and colleagues write. During the study period, there was a 13-fold increase in hospitalisations for women having bariatric surgery for the first time, the analysis found. Compared with women in the general population, those who had bariatric surgery had higher rates of high blood pressure, diabetes and preterm deliveries overall. But women who had bariatric surgery between their first and second pregnancies were 61 per cent less likely to experience high blood pressure, 37 per cent less likely to have infants that were large for their gestational age, 63 per cent less likely to have a preemie and 36 per cent less likely to have their baby sent to the neonatal intensive care unit (NICU) than in their first pregnancies. Women who had surgery and those in the general population were around the same age when they had their first pregnancy. But the women who had bariatric surgery waited an average of two years longer to have their second child, the study found. The women who had bariatric surgeries between pregnancies were also more likely to use assistive reproductive technology (ART) to conceive and to have multiples. Even though diabetes and high blood pressure rates were higher for women who had bariatric surgery between pregnancies, these women did have a bigger drop in the risk of these complications from one pregnancy to the next compared to the general population. After bariatric surgery, women’s risk of high blood pressure in the second pregnancy fell by 67 per cent, compared with a 49 per cent reduction for women who didn’t have the weight loss procedures. And the risk of gestational diabetes, a form of diabetes that develops during pregnancy, dropped by 39 per cent in second pregnancies for women who had bariatric surgery, compared with a 24 per cent decline for women who didn’t have surgery. This difference, however, was too small to rule out the possibility that it was due to chance. Although preterm birth rates were higher in the bariatric group in first pregnancies, in second pregnancies there was a 63 per cent reduction in the odds of preterm birth in the bariatric surgery group compared with a 20 per cent reduction for women who didn’t have surgery.