Despite the positives, the risk for harm was higher in a number of outcomes. Babies were more likely to be small for gestational age, have intrauterine growth restriction (OR, 2.16; 95% CI, 1.34-3.48; NNTH, 21) ,and be delivered preterm (OR, 1.35; 95% CI, 1.02-1.79; NNTH, 35).
A secondary analysis revealed that malabsorptive surgeries resulted in a significantly greater decrease (P = .012) in large babies (OR, 0.28; 95% CI, 0.22-0.36), compared with restrictive surgeries (OR, 0.50; 95% CI, 0.35-0.73). This analysis also revealed that malabsorptive bariatric surgeries corresponded to an increase in the number of small babies (OR, 2.39; 95% CI, 1.94-2.94; P = .023).
The increased risk of smaller babies may be caused by micronutrient deficiencies in pregnancy, according to Dr. Kwong. Nutritional deficiencies are reported in up to 80% of bariatric surgery patients, malabsorptive patients in particular.
“Common nutrient deficiencies after bariatric surgery include protein, B vitamins, fat-soluble vitamins, essential fatty acids, and minerals (zinc and copper), which may persist throughout pregnancy,” wrote Dr. Kwong and his colleagues.