Abstract: Background：The incidence of high serum homocysteine (HHcy) was 37.2% in the whole population. The level of male Hcy and the incidence of male HHcy in families preparing for pregnancy are unknown. Objective：To investigate the status of male Hcy in families preparing for pregnancy and analyze its influencing factors. Design：A cross-sectional survey. Methods：In the Shanghai Parent Child Birth Cohort (SPCC) from March 2016 to January 2022, men were recruited from 16 general hospitals or district maternal and child health hospitals or institutes in 9 districts of Shanghai for pre-pregnancy examination. Socio-demographic information, folic acid supplement use, smoking and alcohol consumption in the past 3 months were collected through questionnaires, and blood samples were collected to detect Hcy (≥15 μmol·LL-1 as HHcy). Main outcome measures：Indicators influencing male Hcy in families preparing for pregnancy. Results：A total of 16,242 men from preconception families were included in this analysis. Their ages ranged from 21.4 to 67.0 years, with a mean age of 30.5±4.5 years. Among them, 51.8% were younger than 30 years old, 47.1% had a body mass index (BMI) of ≥24 kg-2, 83.5% had an education level of a bachelor's degree or lower, and 56.2% had an annual household income of less than 200,000 RMB. The usage rate of folic acid supplements was 6.6%. The mean homocysteine (Hcy) level was 10.9 μmol·L-1 (95% CI: 8.9-13.9), with 20.5% of participants classified as having high Hcy (≥15 μmol·L-1). Multivariate logistic regression analysis revealed that folic acid supplementation (OR=0.48, 95% CI: 0.38-0.60), older age (OR=0.82, 95% CI: 0.74-0.91), higher household income (OR=0.86, 95% CI: 0.77-0.96), and residence in a traditional urban area (OR=0.84, 95% CI: 0.73-0.96) were protective factors associated with a lower risk of high Hcy levels. Conversely, smoking (OR=1.20, 95% CI: 1.09-1.33) was found to increase the risk of high Hcy levels. Conclusion：Hcy levels in men preparing for pregnancy are relatively high, with one in five men experiencing HHcy. Health education should focus on promoting behaviors that lower Hcy levels, such as smoking cessation and folic acid supplementation.

Key words: Men preparing for pregnancy, Homocysteine, Hyperhomocysteinemia, Cohort study