Introduction

A short interpregnancy interval increases the risks of maternal and infant mortality and morbidity. Early studies have shown that closely spaced pregnancies are associated with adverse maternal and infant outcomes.(1, 2) Family planning can prevent more than 30% of maternal deaths and 10% of child mortality when couples space their pregnancies 2–3 or more years apart.(3) In 2013, WHO recognized postpartum family planning (PPFP) as one of the top priorities with respect to global reproductive health issues.(4)
Postpartum contraceptive use varies among countries. A previous study showed that 72% of women used a contraceptive method by 3 months after childbirth in the United States.(5) In 21 low- and middle-income countries, the polled one-year contraceptive use rate for modern methods was 41.2%. (6) Studies in Shanghai showed that approximately 70% of migrant women in a suburban district and 88% of those living in downtown used contraceptives in the first 12 months postpartum. (7, 8) Kang et al. found that only 66% of postpartum women in rural areas of Hunan Province adopted contraceptive methods.(9) We did not uncover any reports on overall postpartum contraceptive use nationwide in China.
Globally, an estimated 99 million unintended pregnancies occurred annually between 2010 and 2014. Of them, 56% ended in induced abortion.(10) Ahrens et al. estimated that approximately 36% of pregnancies conceived within 18 months postpartum in the United States were unintended.(11) Moore et al. showed that birth-to-pregnancy intervals in 50% or more of pregnancies in 21 low- and middle-income countries were less than 23 months.(12) Xiao et al. demonstrated that 10% of women of reproductive age in Enshi, Hubei province of China, experienced unintended pregnancies during the first year after delivery.(13) None of them reported the prevalence of abortion during postpartum period.
Approximately 10 million abortions (9.6–9.9 million in 2016–2018) are performed each year in China.(14) Reducing the number of abortions has been recognised by Chinese health authorities as one of the major approaches to improving women’s reproductive health, and the health administrators from both central and local governments and a large number of family planning service providers have realised the importance of PPFP services for postpartum women. However, our knowledge of postpartum contraception, unintended pregnancy, and abortion across China is still very limited. We therefore conducted the present retrospective cohort study with the primary aim of exploring the prevalence of unintended pregnancy in the extended postpartum period (12–24 months after childbirth) in eastern, central, and western regions of China. Our secondary aims included the investigation of the prevalence of contraception and abortions during postpartum period. This information is essential for designing appropriate interventional PPFP strategies that will contribute to the reduction of unintended pregnancies and induced abortions in China overall.