The paper by France’s University Hospital of Angers was presented on Friday at the 55th Annual European Society for Paediatric Endocrinology Meeting.
The findings could lead to different advice and clinical care for pregnant women who have undergone gastric bypass surgery.
‘Maternal obesity can lead to health conditions for the newborn, such as high birth weight and low blood sugar,’ says Maxime Gerard, lead researcher of the study.
‘It can also cause birthing complications, and gastric bypass can prevent these.
‘But our study showed that gastric bypass could have other effects on newborns.’
Women treated with gastric bypass surgery are advised to wait 18 months after the procedure before trying to become pregnant in order to establish a stable, healthy weight.
They must also follow a daily multivitamin supplementation regime and receive regular clinical follow up before, during and after the pregnancy.
Despite these precautions, a team of clinical researchers found that the birth-weight of babies born to gastric bypass mothers was on average 0.7lb lower than average, and that 23 per cent of neonates were small for their gestational age.