Baseline characteristics (socio-demographic characteristics).

<p>EP, ectopic pregnancy; IUP, intrauterine pregnancy; NonP, nonpregnancy; LNG-EC, levonorgestrel emergency contraception.</p>a<p>The sum does not necessarily equal the sample size for all variables because of missing data.</p>b<p>Occasional smoker: cigarette smoking more than 4 times a week but an average of less than one cigarette per day. Regular smoker: smoking more than one cigarette per day continuously or over a 6-month period.</p>c<p>Center 1 = International Peace Maternity and Child Health Hospital; Center 2 = Shanghai First People’s Hospital; Center 3 = Songjiang Central Hospital; Center 4 = Songjiang Maternity and Child Health Hospital; Center 5 = Minhang Central Hospital.</p><p>Baseline characteristics (socio-demographic characteristics).