Natural Prostaglandins for Induction of Labor and Preinduction Cervical Ripening

Maternal and Neonatal Outcomes Associated with Amniotomy among Nulliparous Women Undergoing Labor Induction at Term

OBJECTIVE

The aim of the study is to evaluate the association between amniotomy at various time points during labor induction and maternal and neonatal outcomes among term, nulliparous women.

STUDY DESIGN

Secondary analysis of a randomized trial of term labor induction versus expectant management in low-risk, nulliparous women (2014-2017) was conducted. Women met inclusion criteria if they underwent induction ≥38 weeks' gestation using oxytocin with documented time and type of membrane rupture. Women with antepartum stillbirth or fetal anomaly were excluded. The primary outcome was cesarean delivery. Secondary outcomes included maternal and neonatal complications. Maternal and neonatal outcomes were compared among women with amniotomy versus women with intact membranes and no amniotomy at six 2-hour time intervals: before oxytocin initiation, 0 to <2 hours after oxytocin, 2 to <4 hours after, 4 to <6 hours after, 6 to <8 hours after, and 8 to <10 hours after. Multivariable logistic regression adjusted for maternal age, body mass index, race/ethnicity, modified Bishop score on admission, treatment group, and hospital (as a random effect).

RESULTS

Of 6,106 women in the parent trial, 2,854 (46.7%) women met inclusion criteria. Of these 2,340 (82.0%) underwent amniotomy, and majority of the women had amniotomy performed between 2 and <6 hours after oxytocin. Cesarean delivery was less frequent among women with amniotomy 6 to <8 hours after oxytocin compared with women without amniotomy (21.9 vs. 29.7%; adjusted odds ratio 0.61, 95% confidence interval 0.42-0.89). Amniotomy at time intervals ≥4 hours after oxytocin was associated with lower odds of labor duration >24 hours. Amniotomy at time intervals ≥2 hours and <8 hours after oxytocin was associated with lower odds of maternal hospitalization >3 days. Amniotomy was not associated with postpartum or neonatal complications.

CONCLUSION

Among a contemporary cohort of nulliparous women undergoing term labor induction, amniotomy was associated with either lower or similar odds of cesarean delivery and other adverse outcomes, compared with no amniotomy.

Repeated dose of prostaglandin E2 vaginal insert when the first dose fails

Objective

To compare the obstetric and neonatal outcomes of patients treated with repeated-dose prostaglandin E2 (dinoprostone) vaginal insert when the first dose fails.

Materials and Methods

This retrospective study included 1.043 pregnant women who received dinoprostone for labor induction between November 2012 and August 2015. Pregnant women were divided into two groups according to the number of dinoprostone administrations: group 1, single-dose dinoprostone (n=1.000), and group 2, repeated-dose dinoprostone (n=43). Intrapartum, postpartum, and neonatal outcomes of the pregnant women were compared.

Results

Vaginal delivery rate was 65% in group 1 and 30.2% in group 2 (p=0.001). The need for the neonatal intensive care unit was found in 44 pregnant women (4.4%) in group 1 and 6 pregnant women (13.6%) in group 2 (p=0.006).

Conclusion

When obstetric and neonatal data were evaluated in our study, we observed that dinoprostone administration was associated with increased cesarean rates and adverse neonatal outcomes with repeated-dose dinoprostone when the first dose failed.

The association between delayed amniotomy and adverse outcomes in labor induction

OBJECTIVE

To assess if delayed amniotomy during labor induction is associated with adverse delivery outcomes.

STUDY DESIGN

Retrospective cohort study of women with a viable, singleton gestation who underwent labor induction at a tertiary-care hospital (4/2014-3/2017). Women were excluded if oxytocin was not used or if spontaneous rupture of membranes (ROM) occurred ≤8 h after oxytocin initiation. The primary outcome was cesarean delivery, and secondary outcomes included postpartum hemorrhage, maternal infectious morbidity, neonatal 5-min Apgar score <7, and neonatal intensive care unit admission. Women were compared by timing of amniotomy: delayed (ROM > 8 h after oxytocin initiation) versus not delayed. Multivariable logistic regression was used to estimate the association between delayed amniotomy and study outcomes.

RESULTS

Of 2081 women who met inclusion criteria, 1125 (before 54%) had delayed amniotomy. Women with delayed amniotomy had ROM 12.7 h (IQR 10.0, 17.9) after oxytocin versus 5.0 h (IQR 3.7, 6.5) without delayed amniotomy. In multivariable regression, delayed amniotomy was associated with increasingly higher odds of cesarean as maternal obesity severity increased (aOR 1.58, 95 %CI 1.24-2.03 at BMI 30 kg/m²; aOR 2.15, 95 %CI 1.45-3.21 at BMI 40 kg/m²; aOR 2.93, 95 %CI 1.54-5.57 at BMI 50 kg/m²).

CONCLUSION

Delayed amniotomy >8 h after starting oxytocin for labor induction was associated with higher odds of cesarean delivery. Significant delay in ROM should be avoided during labor induction.

Labor Induction Techniques: Which Is the Best?

Induction of labor is a common procedure undertaken whenever the benefits of prompt delivery outweigh the risks of expectant management. Cervical assessment is essential to determine the optimal approach. Indication for induction, clinical presentation and history, safety, cost, and patient preference may factor into the selection of methods. For the unfavorable cervix, several pharmacologic and mechanical methods are available, each with associated advantages and disadvantages. In women with a favorable cervix, combined use of amniotomy and intravenous oxytocin is generally the most effective approach. The goal of labor induction is to ensure the best possible outcome for mother and newborn.

Perinatal outcomes following labor induction with dinoprostone in pregnancies with borderline amniotic fluid index at term: A clinical observation study

AIM

To compare perinatal outcomes of dinoprostone for induced labor in pregnancies with a borderline versus normal amniotic fluid index (AFI) at term, and to investigate the related factors affecting outcomes of cesarean section.

METHODS

The retrospective study was carried out in Hubei Maternal and Child Health Hospital with singleton pregnancies of 37-42 weeks' gestation from January to August 2016. A total of 992 subjects were divided into two groups: borderline AFI group (n =125) with 5 < AFI ≤ 8 and normal AFI group (n = 867) with 8 < AFI ≤ 24.

RESULTS

Time to delivery (P =0.004) and use of oxytocin augmentation (P = 0.011) were significantly lower in pregnancies with borderline AFI. There were no significant differences between the two groups in terms of delivery mode, time to onset of labor, fetal distress, Apgar scores, meconium-stained amniotic fluid, birth weight, or incidences of admission to neonatal intensive care unit (NICU). Gestational hypertension and birth weight were the major factors affecting outcomes of cesarean section in the borderline group (odds ratio [OR] = 13.61, 95% confidence interval [CI] 1.96-94.49, P =0.008 and OR = 1.003, 95% CI 1.001-1.005, P =0.001, respectively). Maternal age (OR = 1.12, 95% CI 1.06-1.19, P < 0.001), parity (OR = 7.57, 95% CI 3.05-18.76, P < 0.001), biparietal diameter (OR = 0.55, 95% CI 0.33-0.91, P = 0.021), and meconium-stained amniotic fluid (OR = 1.56, 95% CI 1.12-2.17, P = 0.009) were related factors in the normal group.

CONCLUSION

The perinatal outcomes of dinoprostone for induced labor are comparable between the two groups. Gestational hypertension and birth weight are factors related to outcomes of cesarean section in the borderline group.

Yimu San improves obstetric ability of pregnant mice by increasing serum oxytocin levels and connexin 43 expression in uterine smooth muscle

Prolonged farrowing remains one of the critical challenges in intensive pig farming. This study aims to explore the effects and mechanism of Yimu San (YMS), a Chinese veterinary medicine micro mist, on delivery ability with mouse models. Thirty-two pregnant mice were randomly divided into a control group and low-YMS, med-YMS, and high-YMS groups. The labor process time and stillbirth rate were recorded, the levels of serum oxytocin and prostaglandin E₂ (PGE₂) were measured with enzyme-linked immunosorbent assay (ELISA). Contractility measurements of the isolated uterus and the expression of connexin 43 (Cx43) in uterine smooth muscle were evaluated. The results showed that compared with the control group, the birth process time and stillbirth rate in the med-YMS and high-YMS groups were remarkably lower. The in vitro uterine contractions, levels of oxytocin, PGE₂, and Cx43 in the med-YMS and high-YMS groups were significantly higher than those in the control group. The differences of the above measurements between the low-YMS group and the control group were not obvious. It can be speculated that YMS could significantly promote labor in pregnant mice by enhancing the levels of oxytocin, Cx43, and PGE₂.

Comparison between vaginal and sublingual misoprostol 50 µg for cervical ripening prior to induction of labor: randomized clinical trial

OBJECTIVE

To compare the effectiveness and safety of sublingual versus vaginal misoprostol on improving the Bishop score after 6 h of administration.

METHODS

Randomized clinical trial which includes pregnant women in gestational ages from 32/0 to 41/6, with indication of induction of labor with misoprostol. Bishop score was assessed at the time of induction and 6 h after administration of 50 µg misoprostol. Analysis was made over difference in mean Bishop score of 2 points, using a standard deviation of 2, with 90% power, reaching a 95% confidence interval.

RESULTS

102 patients were studied, 51 received sublingual misoprostol, and 51 received vaginal misoprostol. There was a statistically significant difference in cervical modifications in global terms regardless of the administration route at 6 h (P < 0.05). When analyzing each group, there was no significant difference for the mean and standard deviation for Bishop score for sublingual and vaginal route (P = 0.761). There was no significant difference in terms of mode of delivery, Apgar score, cord pH, nor in the presence of complications.

CONCLUSION

There is no statistically significant difference in terms of administration route for cervical ripening using misoprostol 50 µg, whether it was sublingual or vaginal.

TRIAL REGISTRATION NUMBER

NCT02732522. Registry website: https://clinicaltrials.gov/ .

Patient safety during induction of labor

Rates of induction of labor have risen rapidly since 1990, from 9.6% in that year to a peak of 23.8% of the 2010 singleton births in the United States. Even as the definition of term pregnancy has been refined to reflect the continuing maturation needs of the fetus, and mothers have been encouraged to "go the full forty," management strategies for pregnancy conditions that increase risk have included early induction. Labor induction should only be undertaken when there are specific indications for interrupting the normal processes of pregnancy. These indications may relate to maternal, fetal, or placental conditions or simply reflect the understanding that in all pregnancies, the placenta will eventually lose its ability to adequately provide oxygen, nutrition, and waste removal for the fetus. Patient safety-for both the mother and the child-can be improved when clinicians practice within clinical guidelines that follow the best available evidence and women are able to make informed decisions regarding plans for labor.

Home cervical ripening with dinoprostone gel in nulliparous women with singleton pregnancies

OBJECTIVE

To evaluate whether home cervical ripening is safe and results in shorter hospital stay.

METHODS

This was a retrospective cohort study of women with singleton pregnancies having induction of labor for postmaturity at a single center between January 2007 and June 2010. Women were offered home cervical ripening with 1 mg dinoprostone gel if they were nulliparous, had uncomplicated singleton pregnancies, and the indication for induction was postmaturity.

RESULTS

Nine hundred seven of 1,536 (59.1%) nulliparous women having induction of labor for postmaturity were eligible for home cervical ripening. The median number of hours at home was 11.76 hours (range 0-24.82 hours). There were no cases of birth outside of the hospital, uterine rupture, or significant neonatal morbidity or neonatal death related to home cervical ripening. Eighty-five (5.5%) women who underwent hospital cervical ripening because of maternal preference or social issues formed a hospital cervical ripening comparison group. There was no significant difference in the total number of hours before delivery spent in the hospital between the two groups (26.25; 95% confidence interval [CI] 25.27-27.23 in home cervical ripening group compared with 24.28; 95% CI 22.5-26.0 in the hospital group; P=.26).

CONCLUSIONS

Clinical outcomes are comparable in nulliparous women who receive a single dose of dinoprostone gel for home cervical ripening compared with those who undergo hospital cervical ripening. However, preadmission home cervical ripening with 1 mg dinoprostone does not decrease the number of hours women spend in the hospital.

LEVEL OF EVIDENCE

II.

Early amniotomy after vaginal misoprostol for induction of labor: a randomized clinical trial

OBJECTIVES

To test the effectiveness and safety of early amniotomy after vaginal misoprostol for the induction of labor.

STUDY DESIGN

A randomized clinical trial that included 320 women with medical or obstetric indication for labor induction. They were randomly assigned into two equal groups, amniotomy group and control group. Each participant received vaginal misoprostol 50 μg every 6 h for induction of labor. In amniotomy group, amniotomy was done in the early active phase of labor while in the control group, the membranes were left to rupture spontaneously or as judged by the senior resident in the duty.

RESULTS

More subjects in the amniotomy group achieved vaginal delivery within 24 h than in the control group [117 (73.13 %) vs. 105 (65.63 %)]. Subjects in the amniotomy group reported shorter induction to delivery interval (09.72 ± 4.61 h vs. 13.61 ± 5.61, P = .002), and better neonatal outcome compared to the control group. There were no statistically significant differences between both group with regard to number of doses of misoprostol, need for oxytocin, Cesarean Section indication and maternal side effects.

CONCLUSION

Early amniotomy after vaginal misoprostol for labor induction is associated with higher successful vaginal delivery rate, shorter labor duration and better neonatal outcome.

Structural insights into the evolutionary paths of oxylipin biosynthetic enzymes

The oxylipin pathway generates not only prostaglandin-like jasmonates but also green leaf volatiles (GLVs), which confer characteristic aromas to fruits and vegetables. Although allene oxide synthase (AOS) and hydroperoxide lyase are atypical cytochrome P450 family members involved in the synthesis of jasmonates and GLVs, respectively, it is unknown how these enzymes rearrange their hydroperoxide substrates into different products. Here we present the crystal structures of Arabidopsis thaliana AOS, free and in complex with substrate or intermediate analogues. The structures reveal an unusual active site poised to control the reactivity of an epoxyallylic radical and its cation by means of interactions with an aromatic pi-system. Replacing the amino acid involved in these steps by a non-polar residue markedly reduces AOS activity and, unexpectedly, is both necessary and sufficient for converting AOS into a GLV biosynthetic enzyme. Furthermore, by combining our structural data with bioinformatic and biochemical analyses, we have discovered previously unknown hydroperoxide lyase in plant growth-promoting rhizobacteria, AOS in coral, and epoxyalcohol synthase in amphioxus. These results indicate that oxylipin biosynthetic genes were present in the last common ancestor of plants and animals, but were subsequently lost in all metazoan lineages except Placozoa, Cnidaria and Cephalochordata.

Effects of gestational age on prostaglandin EP receptor expression and functional involvement during in vitro contraction of the guinea pig uterus

Prostaglandin E(2) (PGE(2)) exerts diverse biological effects through four G-protein-coupled cell surface receptor subtypes, EP1-4. This study's objective was to characterize EP1-4 receptor mRNA expression within pregnant guinea pig myometrium during early implantation stage (gestation day [GD] 6) and late stage gestation (GD 50) and evaluate in vitro contractile activity of receptor subtype selective agonists. Using RT-PCR, qualitative gene expression patterns of EP2, EP3, and EP4 mRNA were detected in the myometrium and remained unchanged between the gestational ages. EP1 mRNA remained undetected in pregnant tissue. In vitro contractile activity was evaluated in GD 6 and GD 50 myometrium using vehicle and EP agonists PGE(2), 17-phenyl trinor PGE(2), sulprostone, misoprostol, and CP-533,536. All spasmogens in pregnant myometrium were EP1/EP3 selective agonists, though likely acting via EP3 receptors in this test model. CP-533,536--a highly selective EP2 receptor agonist--and the vehicle failed to induce myometrial contraction at both gestational ages.