Start taking 0.4 mg of folic acid every day when you prepare to conceive, and keep taking it through the first 3 months of pregnancy

Taking one folic acid pill a day around the time of conception cuts the chance of a neural tube defect in the child by about seven tenths. Neural tube defects are birth defects such as anencephaly and spina bifida. For someone who has already had a child with one of these, the chance that another child has the same problem falls to about one third of what it was.

Cost

A few dozen yuan per bottle. Rural women need not pay; the national free folic acid supplementation program issues it. One pill a day; the hard part is remembering every day

Benefit

A Cochrane systematic review pooled 5 trials and 6708 births and rated the evidence high quality. Daily folic acid before and during pregnancy cut fetal neural tube defect risk to RR 0.31 (95% CI 0.17 to 0.58, the plausible range), about a seven-tenths reduction. For people who had already had a child with a neural tube defect, the risk of another affected child was RR 0.34 (95% CI 0.18 to 0.64), about one third of the original. By subgroup, 0.4 mg and higher doses did not differ in effect. Folic acid alone and a multivitamin did not differ either. The Ministry of Health’s 2010 folic acid supplementation program plan states that rural women preparing to conceive receive free folic acid, “taken from 3 months before pregnancy through the first 3 months of pregnancy,” as 0.4 mg tablets. The US Centers for Disease Control and Prevention notes that neural tube defects form in the first few weeks of pregnancy, often before you know you are pregnant

Notes

The key is to start before pregnancy. Neural tube defects form in the first few weeks; if you wait until a positive test, it may already be late. So if you plan to have a child, start 3 months ahead, as the domestic program does. The same pooled review found no clear effect of folic acid on cleft lip and palate, congenital heart disease, or miscarriage — do not count on it for those. Pregnant people on a fully plant-based diet also need vitamin B12 every day; see Section 20, Item 14 (if you eat plant-based, take vitamin B12 daily). If you are still undecided about when to have a child, the age account is in Section 18, Item 7 (waiting a few more years to have a child).

Sources · 3

1. 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. doi.org/10.1002/14651858.CD007950.pub3
2. 卫生部办公厅 (2010). 2010 年增补叶酸预防神经管缺陷项目管理方案. nhc.gov.cn/wjw/gfxwj/201006/22a0b4d4651e4b6d8…
3. Centers for Disease Control and Prevention. About Folic Acid. cdc.gov/folic-acid/about/index.html