Radin RG, Hatch EE, Rothman KJ, Mikkelsen EM, Sørensen HT, Riis AH, Wise LA. Active and passive smoking and fecundability in Danish pregnancy planners. Fertil Steril. 2014 Jul;102(1):183-191.e. doi: 10.1016/j.fertnstert.2014.03.018