TOPLINE:

A meta-analysis found that multiparous women had lower odds of folic acid uptake from the preconception to the postconception period, including first trimester, than primiparous women despite exposure to antenatal care in previous pregnancies. Reduced uptake was also observed among those at high risk.

METHODOLOGY:

• Researchers conducted a systematic review and meta-analysis of 81 observational studies published in English between 1994 and 2024 — identified through databases searches — to assess whether folic acid uptake differed between multiparous and primiparous women, including high-risk women, before and/or during pregnancy.
• The included studies were cross-sectional (59 studies), cohort (17 studies), and case-control (five studies) designs conducted in hospital-based and population-based settings; a total of 826,855 women were included across 33 countries, most commonly Europe.
• Studies were categorised on the basis of the timing of folic acid supplementation as preconceptional, periconceptional, and postconceptional.
• Study quality and certainty of evidence were assessed using validated tools, and between-study heterogeneity and publication bias were evaluated using standard statistical methods.

TAKEAWAY:

• In a pooled meta-analysis of 25 studies, multiparous women had 29% lower odds of preconceptional folic acid use than primiparous women (adjusted odds ratio [aOR], 0.71; 95% CI, 0.64-0.79; low certainty of evidence; I² = 88.67%).
• Pooled analyses of 29 and 34 studies showed that multiparous women had lower odds of folic acid use than primiparous women during the periconceptional period (aOR, 0.69; 95% CI, 0.64-0.76; low certainty of evidence; I² = 85.61%) and the postconceptional period (aOR, 0.80; 95% CI, 0.74-0.85; low certainty of evidence; I² = 85.52%), respectively.
• When postconceptional intake was analysed by trimester, a pooled analysis of 10 studies showed that multiparous women had 27% lower odds of folic acid use during the first trimester (aOR, 0.73; 95% CI, 0.65-0.82; I² = 78.86%), with no significant difference observed during the second and third trimesters.
• In three pooled studies of women with epilepsy and those at risk of having children with congenital abnormalities, multiparous women had 58% lower odds of preconceptional folic acid use than primiparous women (aOR, 0.42; 95% CI, 0.27-0.64; moderate certainty of evidence; I² = 27.28%).

IN PRACTICE:

"The results of our review suggest that these pregnancy-related services are failing to improve, or even maintain, levels of pre and periconceptional FAS [folic acid supplementation] in future pregnancies," the authors wrote.

"For high-risk women, there is a particular need for coordination among services such as primary care, obstetrics and other specialist services (eg, for diabetes and epilepsy) to emphasise the need to take folic acid supplements before each pregnancy, thereby improving women's capability, motivation and opportunity," they added.

SOURCE:

This study was led by Utibe Ebong, School of Medicine, Ulster University Faculty of Life and Health Sciences, Belfast, Northern Ireland. It was published online on May 04, 2026, in BMJ Open.

LIMITATIONS:

Substantial between‑study heterogeneity lowered the certainty of evidence for most outcomes. The literature search was restricted to publications in the English language alone.

DISCLOSURES:

One author reported receiving funding through the Department for the Economy, with additional funding from the Economic and Social Research Council. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.