Abstract: Objective To evaluate the effect of comprehensive intervention during pregnancy and postpartum on unintended pregnancy.Methods In total,3542 pregnant women in two Maternal and Child hospitals at Pudong New District and Putuo district participated in this intervention survey.The participants were divided into a control(1013) and an intervention group(3136) by the hospital they were recruited from and a structured questionnaire was adopted in the survey.The participants in the intervention group received a comprehensive intervention on postpartum contraception,while those in the control group received only the routine pregnancy and postpartum health care.Results After the intervention,the correct answer rates for the time of initiating contraception after giving birth,time of resuming intercourse,and knowledge about ovulatory period calculation were 69.47%,91.32%,and 42.01% for the intervention group and 45.50%,77.75%,and 46.75% for the control group,respectively,with significant differences in the rates between the tow groups(all P<0.0001).One year after the intervention,the prevalence of postpartum unintended pregnancy was 2.65% for the intervention group and 4.57% for the control group.The participants adopting oral contraceptive and emergency contraception had a higher postpartum unintended pregnancy rate than those using safe period contraception and coitus interruptus.Multivariate analysis showed that postpartum unintended pregnancy in intervention group reduced by 45% compared to that in the control group.The incidence of postpartum unintended pregnancy was influenced by education level and the interaction between the time of initiating contraception and the time of resuming intercourse after giving birth.Conclusion The hospital-based comprehensive intervention has a positive effect on the reduction of postpartum unintended pregnancy.