APOA1 and placenta praevia: Moreover, univariate analysis comparing early preterm birth and full-term birth showed that 10 factors were significantly different between the full-term birth group and the early preterm birth group (P < 0.05), including 3 maternal parameters (age, apolipoprotein A1, and thrombin time), 3 pregnancy related factors (multiple pregnancy, embryo reduction, and placenta previa), 3 factors related to the IVF/ICSI procedure (embryo transfer type, treatment cycles and number of embryos transferred), 1 offspring related factor (infant sex) (Tables 1, 2, 3).