Folate and Vitamin B12 Status among Non-Pregnant, Non-Lactating Women of Reproductive Age and Predicted Risk for Neural Tube Defects, Morogoro Region, Tanzania.

Introduction: Population risk for neural tube defects (NTDs) can be determined using red blood cell (RBC) folate. However, a paucity of biomarker and surveillance data among non-lactating, non-pregnant women of reproductive age (NPWRA) from Africa limits accurate assessment. Our study assessed folate and vitamin B12 status among non-lactating NPWRA and predicted population risk of NTDs in Tanzania.

Methods: A cross-sectional biomarker survey of non-lactating NPWRA (15-49 years) in the Morogoro region, Tanzania was conducted during June-October 2019. Questionnaire interview responses and non-fasting blood samples were collected. Folate was assessed using the CDC microbiologic assay kit and vitamin B12 was measured using an electrochemiluminescence immunoassay. Complex survey design analyses were conducted using SAS-callable SUDAAN (v11.0.1).

Results: Of the 761 participating non-lactating NPWRA, 294 (39.8%) had RBC folate insufficiency (<748 mol/L). The prevalence of RBC folate insufficiency was lower among non-lactating NPWRA living in urban than rural areas (PR: 0.72, 95% CI: 0.52-0.99) but did not differ by age or household wealth index. Vitamin B12 insufficiency was uncommon (< 221 pmol/L, 2.7%). The estimated NTD risk was 10.5 (95% uncertainty interval: 8.1-13.3) per 10,000 births.

Discussion: Elevated NTD risk was predicted in the Morogoro region of Tanzania, where ∼ 40% of non-lactating NPWRA had RBC folate insufficiency and < 3% had vitamin B12 insufficiency. The NTD risk is consistent with surveillance data for the area, limited folic acid fortification of staple foods, and low vitamin B12 insufficiency. Further studies are needed to better understand the context of these findings, especially the impact of micronutrient fortification in Tanzania.