Folic acid in pregnancy: high dose supplements are also recommended after bariatric surgery

Dwyer and colleagues discuss current guidelines for high dose folic acid supplementation in pregnancy.1 High dose supplementation with 5 mg folate daily is strongly recommended in patients with a history of a previous pregnancy affected by neural tube defect. Although the evidence is less compelling, it is also widely advised in those with diabetes or obesity and those taking antiepileptic or folate antagonist medications.1

High dose folate supplementation is also advisable in patients undertaking pregnancy after bariatric surgery. Women of reproductive age (18-45 years) comprise half of all patients who undergo bariatric surgery in the United Kingdom and the United States.23 A systematic review with meta-analysis of women with obesity and infertility found that three fifths conceived spontaneously after bariatric surgery.4 Thus, many women with obesity start or complete their families after bariatric surgery.5 It is recommended that they avoid pregnancy in the first 1-2 years after surgery, while undergoing rapid weight loss, to allow enough time for their diet to become nutritionally stable and varied.6

Folic acid deficiency can occur after bariatric surgery owing to reduced stomach capacity, intestinal bypass, or both. Fetal spina bifida has been reported in pregnancies after gastric bypass surgery.7 But folate can be absorbed throughout the small intestine, and widespread fortification of foods, such as breakfast cereals, and routinely recommended multivitamin supplementation after bariatric surgery8 mean that folate deficiency is uncommon. A large Swedish study that compared singleton live births in women with gastric bypass and matched controls found no cases of neural tube defects in the surgery group and 20 cases (0.07%) among controls. Nevertheless, in the interests of safety, patients planning pregnancy after bariatric surgery should receive specialist dietary support and regular nutritional monitoring including oral supplementation of folic acid 5 mg daily given from preconception to 12 weeks of gestation,89 even if they no longer have clinical obesity.