Abstract Body (Do not enter title and authors here): Background
Elevated homocysteine levels are associated with increased risk of congenital heart disease (CHD) in offspring and cardiovascular diseases (CVDs) in adults. Folic acid supplementation may mitigate these risks. Prior studies have shown that women with a history of a CHD-affected pregnancy may have increased risk of CVD.

Research Question
Does periconceptional folic acid use reduce the risk of CVD later in life among women with a history of a CHD-affected pregnancy?

Goals
To evaluate the association between periconceptional folic acid use and the risk of CVDs later in life among women with a history of a CHD-affected pregnancy.

Methods
Data on 1,423 women who delivered infants with at least one of the selected CHDs and 1,020 women who delivered live-born infants without structural birth defects, August 1997 – December 2011, were obtained from the Arkansas site of the National Birth Defects Prevention Study. Dietary and supplemental folic acid intake, pre-pregnancy hypertension, diabetes, body mass index, race and ethnicity, and age at delivery were obtained via telephone interview. Data were linked to the Arkansas All-Payers Claims Database (2000-2022) to identify women with CVD. CVD was classified using ICD-9 and ICD-10 codes and categorized into ischemic, cerebrovascular, essential hypertension, other heart diseases, other CVDs, and any CVD. Women were followed from the estimated delivery date of their child until the occurrence of a CVD event, death, or the end of the study (January 1, 2023), whichever came first. Both unadjusted and adjusted hazard ratios (aHR) with 95% confidence intervals (CIs) were estimated using stratified Cox proportional hazards regression models.

Results
Among women who reported taking folic acid supplements one month before pregnancy through the end of the first trimester (n=3,363), those with a CHD-affected pregnancy had a 1.4-fold increased risk of developing any type of CVD (95% CI: 1.1, 2.1) compared to women with live-born infants without structural birth defects, after adjusting for potential confounders. In contrast, no risk of CVD was observed among women who did not repot taking folic acid supplements (n=482).

Conclusion
Periconceptional folic acid supplementation, alone, does not lower CVD risk among women with CHD-affected pregnancy. Future studies should explore how later-life factors such as lifestyle, comorbidities, and other confounders impact CVD outcomes in this population.