Zhang Y, Zhang J, Zhao J, et al. - Researchers conducted a retrospective cohort study of a total of 2,301,782 eligible couples participating in the National Free Preconception Check-up Projects from January 1, 2015 to December 31, 2017, with the aim to determine the correlation between couples’ prepregnancy body mass index (BMI) and time to pregnancy (TTP) among those with no prior gravidity. Couples with no prior gravidity exhibited prolonged TTP in correlation with abnormal prepregnancy BMIs in either women or men. Underweight, overweight, or obese status in women and underweight status in men were noted to be linked with couples’ prolonged TTP. For women and men, the optimal BMI levels were 20.61–23.06 kg/m ² and 22.69–27.74 kg/m ², respectively. Hence, they suggest performing scientific management of couples’ prepregnancy BMI as possibly beneficial to enhance their fertility.