Paternal smoking and preterm birth: a population-based retrospective cohort study among non-smoking women aged 20–49 years in rural China

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality, as well as other system immaturity problem. But as one of important environmental tobacco smoking sources of maternal secondhand smoking in the family, paternal smoking is worthy for deep exploring of its potential impacts on PTB. Moreover, evidence on the independent role of preconception paternal smoking is still lacking. Thus, we conducted a population-based retrospective cohort study to evaluate the association between paternal smoking and risk of PTB among among 5,298,043 reproductive-aged couples who participated in the National Free Pre-Pregnancy Checkups Project (NFPCP), regarding outcome events that occurred in 2010–2016.