Effects of Prior Induced Termination of Pregnancy on Complications and Pregnancy Outcomes.

Inclusion Criteria: * women have induced abortion in early pregnancy (\<12 weeks of gestation). * permanent population and no tendency to move. * normal language expression and understanding ability, able to understand research content. * be able and willing to provide written informed consent and effective contact information, and be willing to cooperate with follow-up investigations. Exclusion Criteria: * above the age of 40 * with history of adverse pregnancy and childbirth