Association between BMI and increased time-to-pregnancy in planned pregnancy couples: a cohort study in Guangzhou, China.

Background: This study examines the relationship between overweight and obesity and fertility in the context of China's fertility. Given the inconsistent results in previous research, which mostly focused on females, our study targets couples in Guangzhou. We investigate the relationship between Body Mass Index (BMI) and time-to-pregnancy (TTP) to provide evidence-based strategies for enhancing reproductive outcomes in China.