Background: Bariatric surgery increases the risk of micronutrient deficiency by limiting nutrient intake and absorption. Pregnancy further elevates micronutrient requirements, compounding this risk. International consensus guidelines recommend specific supplement doses during pregnancy post-surgery, but their efficacy is unclear. This study examined adherence to supplement guidelines and the relationship between micronutrient intake (from diet and supplements) and risk of deficiency during pregnancy post-bariatric surgery.
Methods: This prospective study included women aged 18-45 years with singleton pregnancies post-bariatric surgery, recruited before 23-weeks' gestation and followed until birth. Dietary micronutrient intake was assessed using up to nine non-consecutive 24-hour recalls. Supplement dose and adherence was self-reported pre-pregnancy, at enrolment, 28 and 36-weeks’ gestation. Micronutrient deficiency was determined using pregnancy-specific reference ranges. Logistic regression identified predictors for iron, zinc, copper, selenium, folate, and vitamins A, B12, D and E deficiency.
Results: Sixty-nine women, aged 31±4.8 years, participated. Multivitamin use increased from 55% (38/69) pre-pregnancy to 80% (55/69) at enrolment, yet adherence to recommended supplement doses was poor. Adherence was highest for selenium at 28-weeks (59%, 38/65) and lowest for vitamin A (0/68). Despite this, only 18% (8/44) developed vitamin A deficiency. Most participants (89% 56/63) developed a micronutrient deficiency during pregnancy, most commonly iron (78%, 48/58) and vitamin B12 (53%, 26/49. Micronutrient intake did not impact the odds of developing deficiency during pregnancy (p>0.05).
Conclusion: Adherence to supplement recommendations is suboptimal. While micronutrient intake did not predict deficiency, iron and B12 deficiencies were common and warrant routine monitoring in antenatal care post-bariatric surgery.