Folic acid before pregnancy and heart defects in babies
What it found
In a group of women in China, those who took folic acid supplements before pregnancy were less likely to have a baby with a congenital heart defect.
Lower dietary folate during pregnancy was linked to a higher risk.
What they found
Studies in people
Folic acid before pregnancy
Women who took folic acid supplements before pregnancy had a lower risk of having a baby with a congenital heart defect compared with women who did not take them. The link was stronger the longer they took the supplements.
Folic acid during pregnancy
Taking folic acid supplements during pregnancy was not clearly linked to the risk of congenital heart defects.
Low dietary folate
Women with the lowest dietary folate intake during pregnancy (less than 149.88 micrograms per day) had a higher risk of a baby with a congenital heart defect, and a higher risk of patent ductus arteriosus specifically.
Types of heart defect
The lower risk with folic acid before pregnancy was seen for malformations of the great arteries, malformations of the cardiac septa, atrial septal defect, and for babies with more than one heart defect. No clear link was seen for isolated heart defects.
Folate from food and supplements
Women who did not take folic acid supplements and also had low dietary folate had almost twice the risk of having a baby with a congenital heart defect.
What the authors conclude
“Our study suggested that folic acid supplementation before pregnancy was associated with a reduced risk of CHDs, lower dietary folate intake during pregnancy was associated with increased risk.”
Also in their conclusions
- They conclude that folic acid supplementation before pregnancy was associated with a reduced risk of congenital heart defects, and that lower dietary folate intake during pregnancy was associated with increased risk.
- They say the associations varied by subtype of congenital heart defect.
- They call for larger studies to clarify the links by subtype and to identify women who would benefit most from folic acid supplements.
How it was done
Earlier studies on whether folic acid before or during pregnancy lowers the risk of congenital heart defects had given mixed results. The authors wanted to look at folic acid supplements and dietary folate together.
They followed 10,087 women who gave birth at one hospital in Lanzhou, China, between 2010 and 2012. They asked about folic acid supplements and diet, and recorded which babies were born with congenital heart defects.
What it can’t tell you
- This was a study that followed women over time, so it can show links but cannot prove that folic acid directly causes the difference in heart defect risk.
- The number of babies with heart defects was small, which limits how precisely the risks for each subtype could be measured.
- Diet and supplement use were asked about after delivery, so women may not have remembered them exactly.
Who paid
- Funding
- Funded by NICHD NIH HHS (from the PubMed record).
- Conflicts
- Competing Interests: The authors have declared that no competing interests exist.
- Authors work at
- Gansu Provincial Maternity and Child Care Hospital, China; Yale University School of Public Health, United States of America
The paper
- Title
- Maternal folic acid supplementation and dietary folate intake and congenital heart defects
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Mao B, Qiu J, Zhao N, et al (2017). Maternal folic acid supplementation and dietary folate intake and congenital heart defects. PloS one. doi:10.1371/journal.pone.0187996Free full textPubMed 29145433DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error