BACKGROUND AND PURPOSE:

• BMI and hyperglycemia are associated with poor perinatal outcomes including birth defects
• Neovius et al. (JAMA, 2019) sought to determine if gastric bypass surgery is associated with reduced risk for major birth defects

METHODS:

• Nationwide matched cohort study
• Participant groups
  • Live-born singleton infants born to women who underwent
    • Roux-en-Y gastric bypass surgery vs
    • Women who did not undergo bariatric surgery
  • Infants identified via Swedish Medical Birth Register
  • Women undergoing bariatric surgery identified via Scandinavian Obesity Surgery Register
• Study design
  • Matching: Based on factors such as previous history of birth defects, BMI, maternal age, smoking etc.
  • Birth defects identified via National Patient Register and Causes of Death Register
• Data analysis
  • Risk ratios calculated for infants between the two groups

RESULTS:

• 2,998 infants born post-bariatric surgery | 97.4% were matched with 30,573 controls
• In the bariatric surgery group
  • Mean presurgery BMI: 43.5 kg/m2
  • Mean body weight: 122 kg
  • Median surgery-to-conception interval: 1.6 years
  • Mean weight loss: 40 kg | Body weight: 82 kg
  • Diabetes drug use: Decreased from 9.7% prior to surgery to 1.5% during the 6 months before conception
• Major birth defects were less frequent in women who had bariatric surgery
  • Bariatric surgery group: 3.4%
  • Controls: 4.9%
  • Risk ratio 0.67 (95% CI, 0.52 to 0.87)
  • Risk difference, −1.6% (95% CI, −2.7% to −0.6%)
• Major heart defects: 60% of birth defects in the bariatric group
• NTDs
  • Bariatric surgery group: 0 cases
  • Controls: 20 cases

CONCLUSION:

• Infants born to women following gastric bypass had reduced risk of severe birth defects compared to matched controls
• Birth defect rate post-surgery was similar to general population  
• The fact that there are no cases of NTD in the bariatric group is reassuring and challenges previous concerns that gastric bypass could result in folate deficiency leading to birth defects  

Learn More – Primary Sources:

Association of Maternal Gastric Bypass Surgery With Offspring Birth Defects

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Pregnant After Bariatric Surgery – a Risk Factor for Abdominal Surgery?

Is Bariatric Surgery Associated with a Decreased Risk for Breast Cancer?

Results of the DiRECT Trial: Can Weight Loss in a Primary Care Setting Achieve Remission of Type 2 Diabetes?