In this study, we aimed to explore regional differences in maternal lifestyle during pregnancy related to congenital heart defects (cHD) in Shaanxi province, northwestern china. A large-scale epidemiologic survey of birth defects among infants born during 2010-2013, was conducted in Shaanxi province. non-spatial and geographic weighted logistic regression models were used for analysis. the spatial model indicated that passive smoking frequency was positively associated with CHD for 43.3% of participants (P < 0.05), with the highest OR in North Shaanxi and the lowest in South Shaanxi. Approximately 49.2% of all mothers who ever drink tea were more likely to have an infant with cHD (P < 0.05), with the highest OR values observed in North and Central Shaanxi. Additionally, maternal alcohol intake frequency ≥ 1/week was significantly correlated with CHD among about 24.7% of participants (P < 0.05), with OR values ranging from 0.738 (Central Shaanxi) to 1.198 (North Shaanxi). The rates of unhealthy maternal lifestyles during pregnancy associated with CHD differed in various areas of the province. the role of geographical variations in these factors may provide some possible clues and basis for tailoring site-specific intervention strategies. Congenital heart disease (CHD), a serious structural abnormality of the heart or large blood vessels in the intrathoracic, is one of the most common types of birth defects (BD) globally 1,2. Researches have shown that CHD is a major risk factor for infant mortality associated with BD and can lead to chronic disability, morbidity and increased medical costs 3-5. It was previously reported that the prevalence of CHD was highest in Asia, second highest in Europe, and lowest in Africa, reflecting significant geographic differences 6-8. Although environmental and behavioral components play a crucial role in the etiological progression of BD, additional research is still required 9-11. Over the years, numerous studies exploring risk factors for CHD have confirmed that maternal lifestyle-related factors such as smoking and alcohol intake during pregnancy may be responsible for certain categories of congenital defects 1,12-14. Because of socio-cultural and geographical reasons, maternal lifestyle-related factors in pregnancy may be different and population-specific in each area. Study results related to associations of maternal lifestyle factors with CHD have not always been consistent across regions 15. These conflicting results may in part stem from geographic heterogeneity, which would lead to bias in correlation estimates and associated calculations of standard error. In China, the incidence rate of CHD is the highest among BD, and the surgical treatment of CHD infants is estimated to cost 12 billion Yuan per year 16. Our previous study found that the Shaanxi province, which accounts