Supplements
folic acid decreases miscarriage
Part of: 🧪 Folate & L-methylfolate
📅 Last reviewed: 2026-07-15 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
Folic acid supplementation has not been shown to reduce miscarriage in the general pregnant population; the evidence leans against it. This is a narrower question than folate's established role in preventing neural-tube defects, which is a different endpoint and is not in doubt — the two are routinely conflated.
The evidence (6)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| cochrane-miscarriage-2016 2016 · The Cochrane database of systematic reviews | meta-analysis | contradicts | high | Cochrane SR/MA (Balogun 2016; 40 RCT/quasi-RCTs, 276,820 women): 'Folic acid supplementation There was no evidence of any difference in the risk of total fetal loss, early or late miscarriage, stillbirth or congenital malformations between women supplemented with folic acid with or without multivitamins and/or iron compared with no folic acid groups.' Numeric RR and GRADE for this folate contrast are not given in the abstract. Authors' overall conclusion: 'Taking any vitamin supplements prior to pregnancy or in early pregnancy does not prevent women experiencing miscarriage.' Null on a directional claim = contradicts. Population is general pregnancies, not recurrent pregnancy loss. |
| Mao YY, Yang L, Li M, Liu J, Zhu QX, He Y, Zhou WJ 2020 · Nutrients | observational | supports | low | Cohort of 65,643 pregnancies (NFPHEP, China): periconceptional folic acid associated with LOWER spontaneous-abortion risk (aRR 0.52, 95% CI 0.48-0.56), with an earlier-initiation gradient. AUTHORS' OWN CAVEAT: the association 'might not thoroughly account for FA supplementation' and may partly reflect healthcare utilisation - i.e. confounding by engagement with care. Observational benefit sits directly against the Cochrane RCT null. |
| Xie M, Qing X, Huang H, Zhang J 2025 · Medicine | meta-analysis | mixed | low | Systematic review/meta-analysis of 11 RCTs (active folate vs folic acid) in women of childbearing age: active-folate supplementation associated with increased subsequent pregnancy rates (P=.0005) and decreased incidence of adverse pregnancy |
| Chen X, Zhang Y, Yang Q, Zhu H, Hu J, Huang J, Jin L, Zhang X, Dou Y, He W, He Y, Chen H, Yao Q, Peng Y, Ma X, Sheng W, Huang G, Yan W, SPCC group 2026 · MedComm | observational | supports | moderate | Prospective cohort of 11,033 couples + 2862 unpaired mothers: each 100 ng/mL increase in maternal RBC folate associated with 8% lower spontaneous pregnancy loss risk (aRR 0.92, 0.85-0.98); paternal folate 19% lower (aRR 0.81); both parents |
| Hekmatdoost A, Vahid F, Yari Z, Sadeghi M, Eini-Zinab H, Lakpour N, Arefi S 2015 · PLoS One | RCT | tested-null | moderate | Randomized 220 women with 3+ idiopathic recurrent abortions to 'either 1mg folic acid or 1 mg 5-MTHF'; of 135 who conceived, ongoing pregnancy 27/66 folic acid vs 36/69 5-MTHF, 'no significant difference in abortion rate between two groups' and 'no significant relationship between abortion rate and participants’ MTHR genotypes'. No no-folate arm, so no test of folate versus none. |
| Kjaergaard AD, Wu Y, Ming WK, Wang Z, Kjaergaard MN, Ellervik C 2022 · Eur J Clin Nutr | observational | contradicts | moderate | MR: genetically elevated homocysteine NOT causal for pregnancy loss |
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.