Associations between Passive Maternal Smoking during Pregnancy and Preterm Birth: Evidence from a Meta-Analysis of Observational Studies Cui, Hong ; Gong, Ting-Ting ; Liu, Cai-Xia ; Wu, Qi-Jun Abstract Publication: PLoS ONE Pub Date: January 2016 DOI: 10.1371/journal.pone.0147848 Bibcode: 2016PLoSO..1147848C