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.

BACKGROUND: Gestational diabetes mellitus (GDM) brings health issues for both mothers and offspring, and GDM prevention is as important as GDM management. It was shown that a history of GDM was significantly associated with a higher maternal risk for GDM recurrence. The incidence of GDM recurrence was unclear because of the incidence of second-child was low before 2016 in China. We aim to investigate the prevalence of GDM recurrence and its associated high-risk factors which may be useful for the prediction of GDM recurrence in China. METHODS: A retrospective study was conducted which enrolled participants who underwent regular prenatal examination and delivered twice in the same hospital of 18 research centers. All participants were enrolled from January 2018 to October 2018, where they delivered the second baby during this period. A total of 6204 women were enrolled in this study, and 1002 women with a history of GDM were analyzed further. All participants enrolled in the study had an oral glucose tolerance test (OGTT) result at 24 to 28 weeks and were diagnosed as GDM in the first pregnancy according to the OGTT value (when any one of the following values is met or exceeded to the 75-g OGTT: 0 h [fasting], ≥5.10 mmol/L; 1 h, ≥10.00 mmol/L; and 2 h, ≥8.50 mmol/L). The prevalence of GDM recurrence and development of type 2 diabetes mellitus were calculated, and its related risk factors were analyzed. RESULTS: In 6204 participants, there are 1002 women (1002/6204,16.15%) with a history of GDM and 5202 women (5202/6204, 83.85%) without a history of GDM. There are significant differences in age (32.43 ± 4.03 years vs. 33.00 ± 3.34 years vs. 32.19 ± 3.37 years, P  < 0.001), pregnancy interval (4.06 ± 1.44 years vs. 3.52 ± 1.43 years vs. 3.38 ± 1.35 years, P  = 0.004), prepregnancy body mass index (BMI) (27.40 ± 4.62 kg/m2vs. 23.50 ± 3.52 kg/m2vs. 22.55 ± 3.47 kg/m2, P < 0.001), history of delivered macrosomia (22.7% vs. 11.0% vs. 6.2%, P < 0.001) among the development of diabetes mellitus (DM), recurrence of GDM, and normal women. Moreover, it seems so important in the degree of abnormal glucose metabolism in the first pregnancy to the recurrence of GDM and the development of DM. There are significant differences in OGTT levels of the first pregnancy such as area under the curve of OGTT value (18.31 ± 1.90 mmol/L vs. 16.27 ± 1.93 mmol/L vs. 15.55 ± 1.92 mmol/L, P < 0.001), OGTT fasting value (5.43 ± 0.48 mmol/L vs. 5.16 ± 0.49 mmol/L vs. 5.02 ± 0.47 mmol/L, P < 0.001), OGTT 1-hour value (10.93 ± 1.34 mmol/L vs. 9.69 ± 1.53 mmol/L vs. 9.15 ± 1.58 mmol/L, P < 0.001), OGTT 2-hour value (9.30 ± 1.66 mmol/L vs. 8.01 ± 1.32 mmol/L vs. 7.79 ± 1.38 mmol/L, P < 0.001), incidence of impaired fasting glucose (IFG) (fasting plasma glucose ≥5.6 mmol/L) (31.3% vs. 14.6% vs. 8.8%, P < 0.001), and incidence of two or more abnormal OGTT values (68.8% vs. 39.7% vs. 23.9%, P < 0.001) among the three groups. Using multivariate analysis, the factors, such as age (1.07 [1.02-1.12], P = 0.006), prepregnancy BMI (1.07 [1.02, 1.12], P  = 0.003), and area under the curve of OGTT in the first pregnancy (1.14 [1.02, 1.26], P  = 0.02), have an effect on maternal GDM recurrence; the factors, such as age (1.28 [1.01-1.61], P  = 0.04), pre-pregnancy BMI (1.26 [1.04, 1.53], P = 0.02), and area under the curve of OGTT in the first pregnancy (1.65 [1.04, 2.62], P = 0.03), have an effect on maternal DM developed further. CONCLUSIONS The history of GDM was significantly associated with a higher maternal risk for GDM recurrence during follow-up after the first pregnancy. The associated risk factors for GDM recurrence or development of DM include age, high pre-pregnancy BMI, history of delivered macrosomia, the OGTT level in the first pregnancy, such as the high area under the curve of OGTT, IFG, and two or more abnormal OGTT values. To prevent GDM recurrence, women with a history of GDM should do the preconception counseling before preparing next pregnancy.
Adult ; Blood Glucose/metabolism* ; China/epidemiology* ; Diabetes Mellitus, Type 2/epidemiology* ; Diabetes, Gestational ; Female ; Fetal Macrosomia ; Glucose Intolerance ; Humans ; Male ; Pregnancy ; Retrospective Studies