[Effects of interpregnancy interval on pregnancy outcomes of subsequent pregnancy: a multicenter retrospective study].

Objective: To explore the effects of interpregnancy interval (IPI) on pregnancy outcomes of subsequent pregnancy. Methods: A multicenter retrospective study was conducted in 21 hospitals in China. Information of age, height, pre-pregnancy weight, IPI, history of diseases, complications of pregnancy, gestational age of delivery, delivery mode, and pregnancy outcomes of the participants were collected by consulting medical records of pregnant women who had two consecutive deliveries in the same hospital during 2011 to 2018. The participants were divided into 4 groups according to IPI:<18 months, 18-23 months, 24-59 months and ≥60 months. According to the WHO's recommendation, with the IPI of 24-59 months group as a reference, to the effects of IPI on pregnancy outcomes of subsequent pregnancy were analyzed. Stratified analysis was further carried out based on age, history of gestational diabetes mellitus (GDM), macrosomia, and premature delivery, to explore the differences in the effects of IPI on pregnancy outcomes among women with different characteristics. Results: A total of 8 026 women were included in this study. There were 423, 623, 5 512 and 1 468 participants in <18 months group, 18-23 months group, 24-59 months group and ≥60 months group, respectively. (1) The age, pre-pregnancy body mass index (BMI), history of cesarean section, GDM, gestational hypertension and cesarean section delivery rate of <18 months group, 18-23 months group, 24-59 months group and ≥60 months group were gradually increased, and the differences were statistically significant (P<0.05). (2) After adjusting for potential confounding factors, compared with women in the IPI of 24-59 months group, the risk of premature delivery, premature rupture of membranes, and oligohydramnios were increased by 42% (OR=1.42, 95%CI: 1.07-1.88, P=0.015), 46% (OR=1.46, 95%CI: 1.13-1.88, P=0.004), and 64% (OR=1.64, 95%CI: 1.13-2.38, P=0.009) respectively for women in the IPI≥60 months group. No effects of IPI on other pregnancy outcomes were found in this study (P>0.05). (3) After stratified by age and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of oligohydramnios for women with advanced age (OR=2.87, 95%CI: 1.41-5.83, P=0.004); and <18 months could increase the risk of premature rupture of membranes for women under the age of 35 (OR=1.59, 95%CI: 1.04-2.43, P=0.032). Both the risk of premature rupture of membranes (OR=1.58, 95%CI: 1.18-2.13, P=0.002) and premature delivery (OR=1.52, 95%CI: 1.07-2.17, P=0.020) were significantly increased in the IPI≥60 months group. After stratified by history of GDM and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would lead to an increased risk of postpartum hemorrhage for women with a history of GDM (OR=5.34, 95%CI: 1.45-19.70, P=0.012) and an increased risk of premature rupture of membranes for women without a history of GDM (OR=1.44, 95%CI: 1.10-1.90, P=0.009). After stratified by history of macrosomia and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months could increase the proportion of cesarean section for women with a history of macrosomia (OR=4.11, 95%CI: 1.18-14.27, P=0.026) and the risk of premature rupture of membranes for women without a history of macrosomia (OR=1.46, 95%CI: 1.12-1.89, P=0.005). After stratified by history of premature delivery and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of premature rupture of membranes for women without a history of premature delivery (OR=1.47, 95%CI: 1.13-1.92, P=0.004). Conclusions: Both IPI≥60 months and <18 months would increase the risk of adverse pregnancy outcomes in the subsequent pregnancy. Healthcare education and consultation should be conducted for women of reproductive age to maintain an appropriate IPI when they plan to pregnant again, to reduce the risk of adverse pregnancy outcomes in the subsequent pregnancy.目的： 探讨不同妊娠间隔（IPI）对经产妇妊娠结局的影响。 方法： 基于全国14个省区市共21家医院开展多中心回顾性研究，通过查阅病历收集2011—2018年间两次妊娠均在同一家医院分娩的经产妇的年龄、身高、孕前体重、IPI、既往史、妊娠合并症和并发症、分娩孕周、分娩方式、妊娠结局等资料。根据不同IPI分为4组：<18个月组、18~23个月组、24~59个月组和≥60个月组，分析其临床特征和妊娠结局。根据WHO的推荐，以24~59个月组作为参照，比较各组经产妇的妊娠结局。进一步根据年龄、妊娠期糖尿病（GDM）史、巨大儿分娩史和早产史进行分层分析，探讨不同特征经产妇中IPI对其妊娠结局的影响。 结果： 本研究共纳入经产妇8 026例，其中<18个月组、18~23个月组、24~59个月组和≥60个月组分别为423、623、5 512和1 468例。（1）<18个月组、18~23个月组、24~59个月组和≥60个月组的妊娠年龄、本次妊娠前体质指数（BMI）、剖宫产史比例、GDM发生率、妊娠期高血压发生率以及剖宫产术分娩比例均逐渐增加，分别比较，差异均有统计学意义（P均<0.05）。（2）校正混杂因素后，与24~59个月组经产妇相比，≥60个月组经产妇的早产、胎膜早破和羊水过少的发生风险分别增加42%（OR=1.42， 95%CI为1.07~1.88， P=0.015）、46%（OR=1.46， 95%CI为1.13~1.88， P=0.004）和64%（OR=1.64， 95%CI为1.13~2.38， P=0.009），其他组均未见不良妊娠结局的发生风险增加（P均>0.05）。（3）根据妊娠年龄分层，校正混杂因素后，与24~59个月组比较，高龄经产妇≥60个月组羊水过少的发生风险明显增加（OR=2.87， 95%CI为1.41~5.83， P=0.004）；非高龄经产妇<18个月组胎膜早破的发生风险明显增加（OR=1.59， 95%CI为1.04~2.43， P=0.032），≥60个月组胎膜早破（OR=1.58， 95%CI为1.18~2.13， P=0.002）和早产（OR=1.52， 95%CI为1.07~2.17， P=0.020）的发生风险均显著增加。根据有无GDM史分层，校正混杂因素后，与24~59个月组比较，≥60个月组有GDM史经产妇产后出血的风险显著增加（OR=5.34， 95%CI为1.45~19.70， P=0.012），无GDM史经产妇胎膜早破的发生风险显著增加（OR=1.44， 95%CI为1.10~1.90， P=0.009）。根据有无巨大儿分娩史分层，校正混杂因素后，与24~59个月组比较，≥60个月组有巨大儿分娩史经产妇剖宫产术分娩的比例显著增加（OR=4.11， 95%CI为1.18~14.27， P=0.026），无巨大儿分娩史经产妇胎膜早破的发生风险显著增加（OR=1.46， 95%CI为1.12~1.89， P=0.005）。根据有无早产史分层，校正混杂因素后，与24~59个月组比较，≥60个月组无早产史经产妇胎膜早破的发生风险显著增加（OR=1.47， 95%CI为1.13~1.92， P=0.004）。 结论： IPI≥60个月或<18个月均会造成经产妇不良妊娠结局的发生风险增加，应通过对育龄期妇女孕前咨询和产后保健的健康教育，指导育龄期妇女再次妊娠时保持适宜的IPI，以降低不良妊娠结局的发生风险。.