Risk of low birth weight and micronutrient deficiencies in neonates from mothers after gastric bypass: a case control study

Background: An increased risk of small-for-gestational-age infants after maternal bariatric surgery has been shown. The risk of micronutrients deficiencies in these neonates is unclear.

Objective: To screen for micronutrients deficiencies in newborns of mothers with gastric bypass.

Settings: University hospital in Angers, France.

Methods: This study compared the clinical and cord blood biological characteristics of 56 newborns of mothers with prior Roux-en-Y gastric bypass (RYGB) and 56 newborns of nonobese healthy mothers after normal pregnancy (controls), followed between January 3, 2008 and October 31, 2012. Cord blood micronutrients concentrations from controls were used for establishing normative data. After RYGB, the women took daily micronutrients supplements.

Results: RYGB mothers lost 18.1±6.3 kg/m² of body mass index (BMI) in the 11-69 months between surgery and pregnancy onset (percentage of excess weight loss 79±20%), reaching BMI of 30.1±6.0 kg/m² compared with 22.3±4.0 kg/m² in the controls (P<.05). Neonates born to RYGB mothers were small-for-gestational-age in 23% of cases versus 3.6% in the control group (P<.01). A higher percentage of RYGB neonates had cord blood concentrations below the 2.5 percentile for calcium (19% versus 2%), zinc (13% versus 3%,), iron (19% versus 2%), and vitamin A (13% versus 3%), and over the 97.5 percentile for magnesium (13% versus 3%), vitamin E (16% versus 3%), 25-hydroxy-vitamin D (13% versus 2%), and vitamin B12 (14% versus 2%) (P<.05 for all comparisons).

Conclusion: Neonates from RYGB mothers showed cord blood micronutrient differences compared with neonates from healthy mothers. The comparison with neonates from morbidly obese women is still to be done.