Fetal growth and fetoplacental circulation in pregnancies following bariatric surgery: a prospective study

To investigate the intrauterine fetal growth pattern and fetoplacental circulation in pregnancies following bariatric surgery.

Prospective study.

Maternity Unit, UK.

One hundred and sixty-two pregnant women; 54 with previous bariatric surgery and 108 with no surgery but similar booking body mass index.

Participants were seen at 11-14, 20-24, 30-33 and 35-37 weeks of gestation and an oral glucose tolerance test (OGTT) was performed at 27-30 weeks. Fetal head and abdominal circumference (AC), femur length (FL), estimated fetal weight (EFW) and fetoplacental Dopplers were measured at three time-points in pregnancy. Birthweight (BW) was recorded. Variables were modelled after adjustment for maternal/pregnancy characteristics. Model estimates are reported as posterior means and quantile-based 90% credible intervals (CrI).

Fetal biometry, fetoplacental Doppler, BW.

Compared with the no surgery group, the post-bariatric surgery group had lower EFW during gestation (up to -120 g; [-189 g, -51 g] lighter) at 35-37 weeks, with smaller AC and FL. Similarly, infants of mothers with previous bariatric surgery had lower average BW [-202 g [-330 g, -72 g] lighter). Overall, there was no difference in the fetoplacental Doppler indices between groups but maternal glucose levels at OGTT were positively correlated with third-trimester EFW and BW.

Fetuses of women with previous bariatric surgery are smaller during pregnancy and at birth, compared with those of women without such surgery, and this may be related to the lower maternal glucose levels seen in the former population. The fetoplacental circulation appears not to be altered by maternal weight loss surgery.

Offspring of post-bariatric women are smaller during pregnancy and at birth but this is not due to placental insufficiency.