Start 0.4 mg of folic acid daily when planning pregnancy and continue through the first three months
Daily folic acid around conception reduces neural tube defects, such as anencephaly and spina bifida, by roughly 70% in the pooled research. Among people with a previous affected pregnancy, recurrence risk was about one-third of that without supplementation. Discuss your dose with a clinician if you have a previous affected pregnancy or other risk factors.
What it takes
A bottle costs tens of RMB in China. China's free folic acid supplementation program provides it to eligible rural women. Taking it daily requires remembering the dose.
What you may gain
A Cochrane review pooled five trials and 6,708 births and rated the evidence high quality. Daily folate supplementation around conception reduced neural tube defects, RR 0.31, 95% CI 0.17–0.58, or about a 70% relative reduction. Recurrence after a previously affected pregnancy had RR 0.34, 95% CI 0.18–0.64, approximately one-third of the comparison risk. Subgroup analyses found no clear difference between 0.4 mg and higher doses or between folic acid alone and combinations with other vitamins; these subgroup findings are not a substitute for individualized high-risk dosing advice.
Context & considerations
Starting before conception is crucial: the neural tube closes within about 28 days after conception, much of which may pass before a positive pregnancy test. The source recommends starting three months before trying to conceive. The same review found no clear effect on cleft lip or palate, congenital heart disease, or miscarriage; folic acid is not a remedy for every pregnancy risk.
Research & references
De-Regil LM, Peña-Rosas JP, Fernández-Gaxiola AC, Rayco-Solon P (2015). Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database of Systematic Reviews, (12), CD007950. https://doi.org/10.1002/14651858.CD007950.pub3