Maternal and Neonatal Outcomes in Electively Induced Low Risk Term Pregnancies


Our lecture today will be on maternal and neonatal outcomes in electively induced low risk term pregnancies. You will have a brief introduction concerning definitions, go through methods of induction, and then go right into the research paper. The induction of labor is defined as the artificial initiation of contractions in a pregnant woman who is not in labor to help her achieve successful vaginal birth within 24 to 48 hours. Elective inductions of labor is the induction of labor in the absence of acceptable fetal or maternal indications. Expectant management is defined as non intervention at any particular point in time and allowing pregnancy to progress to a further gestational age. Expectant management may progress into spontaneous labor or indicated induction of labor. Methods of induction of labor includes membrane sweeping, pharmacological, mechanical, and surgical. Under pharmacological, there the use of prostaglandin E1 E2 and oxytocin. As for mechanical methods of induction, there is balloon catheterization, extra amniotic saline infusion, laminaria tents. And for surgical, there is amniotomy. In conventional obstetric teaching, elective induction of labor is associated with increased maternal morbidities such as increased Cesarean section rates, increased length of labor, and increased infection. But this was in comparison to spontaneous labor, rather than the clinical alternative of expectant management. In recent studies comparing expectant management and elective induction of labor, it was found that Cesarean rates were actually decreased, as well as decreased neonatal morbidities, such as Meconium aspiration, better five minute APGAR score, lowered infection, decreased ventilation use, decreased composite morbidity, and decreased NICU admissions. The current opinion is that it is favorable to compare elective inductions of labor to expectant management, rather than spontaneous delivery because this corresponds to the actual measured outcomes, and also accounts for obstetric complications that might occur during the alternative. Additionally, there has been limited data with consideration of cervical status, in terms of Bishop score, and for low risk obstetric population. The current study accounts for this by stratifying cervical status as favorable and unfavorable. The current study uses modified Bishop score, which includes cervical dilation, cervical effacement, and station. A favorable, or ripe, cervix is defined as a modified Bishop score greater than 4. Unfavorable, or unripe, cervix is defined as modified Bishop score less than or equal to 4. 51% of the patients had all five components Bishop scored reported, while 84% had information on cervical dilation, effacement, and station. That’s why the modified Bishop score was used. Now that we understand the conventional obstetric teaching on elective induction of labor, we will dive straight into the paper and discuss the study population. The study is a retrospective cross-sectional study involving deliveries from 2002 to 2008 from 12 clinical centers and 19 hospitals, representing 9 ACOG districts. The study looks at low risk populations, limited to first singleton pregnancy, terms gestation 37 to 42 weeks, in vertex presentation. There is an exclusion of prior uterine scar or elective Cesarean deliveries. Exclusion of chronic maternal conditions that may lead to indicated delivery, such as diabetes mellitus, chronic hypertension, cardiovascular disease, placenta previa, or human immunodeficiency virus positive status. There was, however, an inclusion of pregnancy related complications, such as preeclampsia, gestational hypertension, abruption or fetal compromise. Here’s a diagram demonstrating the stratification of the study population into the different weeks of gestation. The key question that the study hopes to answer is whether elective induction of labor in low risk term pregnancy confers better maternal and neonatal outcomes in comparison to expectant management. Measurable outcomes include the primary and secondary. The primary outcome includes Cesarean section rates with elective induction, whereas the secondary outcomes include maternal and neonatal morbidities. This diagram demonstrates the different modes of delivery studied within this research paper– non-operative vaginal delivery, operative vaginal delivery, and Cesarean sections. The operative vaginal delivery very includes forcep delivery and vacuum delivery. The results shown here are for non operative vaginal delivery in both nulliparous and multiparous pregnancies with unfavorable or favorable cervix. As you can see from the results, a higher percentage of vaginal delivery is seen in nulliparous and multiparous pregnancies with favorable or unfavorable cervix in elective induction of labor, in comparison to expectant management. In this slide, we look at the Cesarean delivery rates comparing, elective induction of labor and expectant management in both nulliparous and multiparous women with favorable or unfavorable cervix. As you can see in this slide, the significant results are highlighted in yellow. In nulliparous women with unfavorable cervix there is a significant decrease in the amount of Cesarean delivery rates from 37 to 40 weeks gestation. In nulliparous and favorable cervix, there is only a significant difference seen in 38 to 40 weeks. In multiparous women with unfavorable cervix, there’s a difference seen in 38 to 40 weeks, whereas in multiparous with favorable cervix, there is only significant difference seen in 39 and 40 weeks. The secondary maternal outcomes measured were bleeding complications, maternal ICU admission or death, infections, lacerations, and shoulder dystocia. For bleeding complications, they included any use of blood products, or a placental abruption, postpartum hemorrhage, uterine rupture, or hysterectomy. For infections, they looked at intrapartum fevers, chorioamnionitis, endomyometritis, and wound separation. For lacerations, they recorded third or fourth degree perineal, sulcal, or cervical lacerations. Here we look at the maternal results for nulliparous women. As you can see from the slide, highlighted in yellow, the only significance found between elective induction of labor and expectant management in maternal bleeding complication was seen at 38 weeks. In maternal infections, there was a significant difference seen throughout all the weeks, whereas for maternal intensive care admission or death, shorter dystocia, or third or fourth degree perineal or sulcal lacerations, there were no significant difference seen between elective induction of labor and expectant management. In this slide we see the maternal outcomes in multiparous women. Highlighted in yellow we have significant difference in which elective induction of labor had better outcomes than expectant management. Highlighted in orange, we have significant difference in which expectant management had better outcomes than elective induction of labor. In this slide it shows in maternal bleeding complications, elective induction of labor had better outcomes than expectant management at 38 weeks. However, at 39 weeks expectant management had better outcomes than elective induction of labor. With regards to maternal infections, elective induction of labor had better outcomes during the 38 and 39th week. For third or fourth degree perineal or sulcal lacerations, there were significant differences in the 39 and 40th week. For shoulder dystocia, there was a difference seen in 38 weeks. In this slide, we have measurable secondary neonatal outcomes. Composite of major co-morbidities include birth injuries, sepsis, pneumonia, interventricular hemorrhage, aspiration, hypoxic ischemic encephalopathy, seizures, respiratory distress syndrome, oliguria, myocardial injury, and transfusions. This is a continuation of the last slide on composite of respiratory morbidities include oxygen use, continuous positive airway pressure use, transient tachypnea, surfactant administration, as well as perinatal death, including intrauterine fetal demise and neonatal demise. This slide shows the secondary neonatal outcomes in nulliparous and multiparous women. As you can see from the slide, the yellow highlights the significant difference between elective induction of labor and expectant management. For neonatal complication composite in nulliparous women there is a significant difference seen from 38 to 40th week. With neonatal respiratory complications, you also see a significant difference from 38 to 40th week. In multiparous women, there is only a difference in seen in 39th week. In both multiparous and nulliparous women, there is no significant difference for perinatal death between elective induction of labor and expectant management. Summary and implications. For the primary and secondary outcomes, they found that there were reductions in the Cesarean section rates with elective induction regardless of week of gestation, parity, or cervical status. Maternal and neonatal outcomes were better in induction of labor, compared to expectant management of the same week. For nulliparous women, there was decrease in maternal infections and perineal laceration, whereas a multiparous woman there was decrease in maternal infections and shoulder dystocia. Some of the strength of the study included the stratification of labor from 37 weeks to 40 weeks gestation, which encompassed all weeks of term deliveries. And they showed there is no increase in neonatal morbidity after 37 weeks in nulliparous groups. The study population as well is low risk term pregnancy, which is mostly unstudied previously. Another the strength of the study is it included cervical status, which is also absent in previous large analytical studies. Study critique. The study is a retrospective cross-sectional study, so there is still need of Randomized Control Trial data. Recent small RCTs show no increase in Cesarean section delivery rates vs. a reduction reported in this study. There’s also a potential for healthy user bias, in which only women considered more likely to be successful were induced. Clinicians may not attempt induction for various reasons, including Bishop score, and those induced would already have a high likelihood of success. The study also does not differentiate between different modes of induction, which may confound the results. Additionally, significant results of measured outcomes were limited to the mode of delivery and maternal infections. In Vogel et al. 2013, they show that elective induction actually increased NICU and ICU admission rates, as opposed to expectant management. Additionally, the results may not be relevant to other populations, as it is controlled for ethnicity only within US populations. Again Vogel et al. 2013, showed that no reduction of Cesarean deliveries was found in Asian populations. Most related studies comparing elective induction of labor and expectant management looked at late term or post term pregnancies. In late term or post term pregnancies, there are significant results showing benefits to elective induction labor compared to expectant management. However, in term and low risk pregnancies, there has not been demonstrated significant benefit in elective induction of labor in comparison to expectant management. In conclusion, the current study suggests a decrease Cesarean section births, which could potentially increase cost effectiveness and decrease long term complications, and also faster recoveries. However, there is not enough strong evidence to show benefit of elective induction for low risk term pregnancy versus expectant management. There seems to be a need for more well designed, large scale RCTs for a conclusive decision. However, it is known that for a post term or late term pregnancy, there are significant benefits to elective induction of labor compared to expectant management.

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