Effect of Elective Induction of Labor on Pregnancy Outcome in Low-Risk Pregnant Women At or Beyond Later Than Term

Background: Singleton low-risk pregnant women without obstetric or medical complications,can expect to terminate pregnancy by selective induced labor until 41 weeks later.But recent researches showed it is reasonable to offer elective induction of labor to low-risk nulliparous women 39 weeks 0 days of gestation, and this recommend need further research be conducted to measure the impact of this practice.The fundamental question is whether this operation will increase the additional risk of mother and fetus. Objective: To investigate the effect of induced labor on maternal and fetal pregnancy outcome. Methods: The method of this study is a retrospective case-control study.In this study, a total of 4386 pregnant women with singleton low-risk who underwent regular prenatal examination and successful vaginal delivery at or more than 41 weeks 0 days of gestation in Fujian Maternal and Child Health Hospital from January 2014 to December 2018. Review the clinical data,according to the mode of labor initiation, they were divided into induced labor group (2007 cases) and spontaneous onset of labor group (2361 cases). Further stratified analysis was carried out according to age and parity. Two-sample independent t -test and χ 2 test were used to analyze the differences of clinical characteristics such as maternal age and parity between the two groups. Logistic regression model was used to analyze the effect of induced labor on pregnancy outcome. Results: The total duration of labor in the induced labor group was significantly longer than that in the spontaneous onset of labor group[ (9.37±5.37) vs (8.82±5.13)h, P ＜0.001],associated with more postpartum blood loss[ (219.18±188.32) vs (199.95±124.69)mL, P =0.01], and the incidence of severe postpartum hemorrhage(sPPH) was significantly higher[0.8%(16/2007) vs 0.33% (8/2361), P =0.041];increase but no significant difference in the incidence of postpartum hemorrhage(PPH) [3.8 %(77/2007) vs 2.8% (66/2361), P =0.054].However,operative vaginal birth was more common in the induced labor group[3.8 %(77/2007) vs 2.8% (66/2361), P =0.054].Compared with spontaneous onset of labor,NICU admissions were higher with induction[3.8 %(77/2007) vs 2.8% (66/2361), P =0.054];but not significantly increase the risk of the third degree amniotic fluid contamination,placental abruption,birth weight and its distribution, sex of newborn, incidence of neonatal brain injury, incidence of neonatal intraventricular hemorrhage, perinatal death, neonatal hyperbilirubinemia, neonatal septicemia, neonatal pneumonia and Apgar ≤ 7 at birth ( P ＞0.05). After adjusting for age, the operation of induced labor in nulliparous is more likely to occur PPH[2.74 %(55/2007) vs 1.65 %(39/2361); RR =1.557;95% CI: 1.039~2.332, P ＜0.05]. Conclusion: Selective induction of labor increases the complications of mother and child.Low-risk pregnant women should try to avoid induction without medical indications.