Bariatric Surgery and Consequences for Mother and Baby in Pregnancy

Background Roux-en-Y gastric bypass (RYGB) is a well-established treatment of obesity, most often performed in women during their reproductive years. Adverse events related to RYGB include hypoglycemia. Though usually attenuated in pregnancy, the incretin response is reinforced in subjects with RYGB and the resulting changes in insulin and glucagon responses together with the resultant weight loss are possible underlying mechanisms for hypoglycemia. The majorities of women who have undergone RYGB conceive shortly after RYGB and have an increased risk for inappropriate gestational weight gain (GWG) and thereby fetal growth restriction. However, studies of hypoglycemia and GWG in pregnant women following RYGB are lacking. Objective In women with previous RYGB we aim to investigate a) glucose level and incretin response during a mixed meal test (MMT) in early and late pregnancy, b) trimester specific incidence of postprandial hypoglycemia and c) fetal growth. Methods 20 women with RYGB and 20 age-, BMI- and parity-matched controls will be studied with a) 2nd and 3rd trimester 4-hour liquid MMTs, b) 6-days Continuous Glucose Monitoring (CGM) once every trimester and post partum and c) maternal and fetal anthropometrics including antenatal ultrasound examinations and neonatal DXA-scans. The primary outcomes are nadir plasma glucose levels during the 4-hour liquid MMT, number of hypoglycemic episodes during CGM and birthweight standard deviation scores. Discussion A better understanding of maternal metabolism and fetal growth in women with RYGB will support risk stratification, patient information and management both before and during pregnancy.