Pregnancy after surgery is becoming more common due to the improvement of fertility after weight loss surgery. Weight loss from surgery and a better calibrated metabolism in the mother helps to improve the safety of pregnancy from both baby and mother and also reduces the risk of pregnancy complications such as gestational diabetes and macrosomia – a large sized baby. However, there are still risks that can come with pregnancy in WLS patients. These include low birth weight of the baby, small-for-gestational-age infants, increased risk of mortality around birth, and preterm birth (delivery before 37 weeks).

The current recommendation is to wait at least 1 year after weight loss surgery before becoming pregnant. Some surgical practices encourage waiting at least 18 to 24 months after surgery.

The fear is that early pregnancy while a bariatric patient is losing weight and adjusting to their restrictive and/or malabsorptive metabolic procedure may compromise the health of the developing fetus.

In one retrospective research study, many variables were evaluated in pregnant women who had undergone bariatric surgery, in order to determine which risk factors were most associated with preterm birth.

The risk factors for preterm birth after WLS that the study determined was:

• Women having a BMI > 25
• Women who reported severe GI symptoms before surgery (ie: diarrhea, indigestion, constipation, abdominal pain, and reflux)
• Excessive maternal weight gain reduced the odds of preterm birth after WLS (unexpectedly)

The association between severe gastrointestinal symptoms before surgery with preterm birth during pregnancy was thought to be related to the side effects of malnutrition and inflammation.

The finding of excessive maternal weight gain reducing the odds of preterm birth was a surprising and unexpected finding. This finding was not found in research on pregnant women in the non-bariatric population (which typically reports excessive maternal weight gain during pregnancy as a risk factor for preterm birth).

The retrospective study also evaluated whether a malabsorptive procedure like the gastric bypass had any bearing on preterm births. This study, and previous research studies, did not show an increased risk of delivering a baby before 37 weeks gestation. risk factor for preterm birth.

All in all, the main risk factors (from this particular study) suggested that post-bariatric pregnant women with a BMI that was at least overweight or in the obese category, together with pre-operative severe GI symptoms were highest risk for delivering a baby preterm during their pregnancy.

Bibliography
Yu, Yang, et al. “Risk Factors for Preterm Birth in Pregnancies Following Bariatric Surgery: An Analysis of the Longitudinal Assessment of Bariatric Surgery-2.” Surgery for Obesity and Related Diseases, Elsevier, 2 Aug. 2022, https://www.soard.org/article/S1550-7289(22)00593-7/fulltext?dgcid=raven_jbs_etoc_email.