摘要Objective To determine the prevalence and determinants of folic acid (FA) supplementation in Chinese couples planning for pregnancy and in women during early pregnancy. Methods This was a cross-sectional study based on the Shanghai PreConception Cohort (SPCC) study. Data on FA supplementation and socio-demographic features were collected using questionnaires. Couples visiting clinics for pre-pregnancy examination and pregnant women at < 14 gestational weeks were recruited in Shanghai, China, between March 2016 and September 2018. Results Among the pregnancy planners, 42.4％ (4,710/11,099) women and 17.1％ (1,377/8,045) men used FA supplements, while 93.4％ (14,585/15,615) of the pregnant women used FA supplements. FA supplement use was higher in female pregnancy planners who were older (RR: 1.13, 95％ CI: 1.08–1.18), had higher education (RR: 1.71, 95％ CI: 1.53–1.92), and were residing in urban districts (RR: 1.06, 95％CI: 1.01–1.11) of FA supplementation; female pregnancy planners with alcohol consumption (RR: 0.95, 95％ CI: 0.90–0.99) had lower odds of FA supplementation. In early pregnancy, women with higher educational level (RR: 1.04, 95％ CI: 1.03–1.06), who underwent pre-pregnancy examination (RR: 1.02, 95％ CI: 1.01–1.03) had higher odds of using an FA supplement; older aged (RR: 0.99, 95％ CI: 0.98–0.99), and multigravida (RR: 0.97, 95％ CI: 0.96–0.98) had lower odds of FA supplementation. Conclusion Although the majority of pregnant women took FA supplements, more than half of the women planning for pregnancy did not. Urgent strategies are needed to improve pre-conception FA supplementation.