Pre-term cervical ripening and labor induction

Predicting factors for success of vaginal delivery in preterm induction with prostaglandin E2

Objective

To evaluate the efficacy and safety of prostaglandin (PG) E₂ for preterm labor induction and to investigate the predictive factors for the success of vaginal delivery.

Methods

A retrospective cohort study was performed in women (n=155) at 24+0 to 36+6 weeks of gestation who underwent induction of labor using a PGE₂ vaginal pessary (10 mg, Propess) from January 2009 to December 2015. Success rates of vaginal delivery according to gestational age at induction and incidence of intrapartum complications such as tachysystole and nonreassuring fetal heart rate were investigated. Multivariable logistic regression analysis was performed to evaluate the predictive factors for success of labor induction.

Results

The vaginal delivery rate was 57% (n=89) and the rate of cesarean delivery after induction was 43% (n=66). According to gestational age, labor induction was successful in 16.7%, 50.0%, and 62.8% of patients at 24 to 31, 32 to 33, and 34 to 36 weeks, showing a stepwise increase (P=0.006). There were 18 cases (11%) of fetal distress, 9 cases (5.8%) of tachysystole, and 6 cases (3.8%) of massive postpartum bleeding (>1,000 mL). After adjusting for confounding factors, multiparity (odds ratio [OR], 8.47; 95% confidence interval [CI], 3.10 to 23.14), younger maternal age (OR, 0.84; 95% CI, 0.75 to 0.94), advanced gestational age at induction (OR, 1.06; 95% CI, 1.02 to 1.09), rupture of membranes (OR, 11.83; 95% CI, 3.55 to 39.40), and the Bishop score change after removal of PGE₂ (OR, 2.19; 95% CI, 1.0 to 4.8) were significant predictors of successful preterm vaginal delivery.

Conclusion

An understanding of the principal predictive factors of successful preterm labor induction, as well as the safety of PGE₂, will provide useful information when clinicians consult with preterm pregnant women requiring premature delivery.

Different secretion patterns of matrix metalloproteinases and IL-8 and effect of corticotropin-releasing hormone in preterm and term cervical fibroblasts

The aims of the present study were to compare the levels of mRNA and protein expression of matrix metalloproteinase (MMP)-1, -3, -8 and -9 in human cervical tissue in preterm and term labor as well as not in labor and to determine if corticotropin-releasing hormone (CRH) has an effect on MMP-1, -3 and interleukin (IL)-8 secretion in both preterm and term cervical fibroblasts. Cervical biopsies were taken from 60 women: 18 at preterm labor, 7 at preterm not in labor, 18 at term labor and 17 at term not in labor. ELISA and Immulite were used for protein and real-time RT–PCR for mRNA analysis. Cervical fibroblast cultures were incubated for 18 h with different CRH concentrations (10⁻¹³–10⁻⁶ M). The mRNA expression of MMP-1, -3 and -9 was higher in laboring groups compared with term not in labor. Protein levels of MMP-8 and -9 were higher in term in labor group compared with non-laboring groups. There were no significant differences in mRNA and protein expression between the preterm and respective term control groups. CRH significantly increased secretion of IL-8 in preterm and term cervical fibroblasts compared with controls. The secretion of IL-8 and MMP-1 was significantly higher and MMP-3 secretion lower in preterm cervical fibroblasts. In conclusion, cervical ripening at preterm seems to be a similar inflammatory process as at term with CRH involved. However, preterm and term cervical fibroblasts might have different phenotypes based on different secretion patterns of IL-8, MMP-1 and MMP-3.

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.

Corticotropin-releasing hormone, its binding protein and receptors in human cervical tissue at preterm and term labor in comparison to non-pregnant state

BACKGROUND

Preterm birth is still the leading cause of neonatal morbidity and mortality. The level of corticotropin-releasing hormone (CRH) is known to be significantly elevated in the maternal plasma at preterm birth. Although, CRH, CRH-binding protein (CRH-BP), CRH-receptor 1 (CRH-R1) and CRH-R2 have been identified both at mRNA and protein level in human placenta, deciduas, fetal membranes, endometrium and myometrium, no corresponding information is yet available on cervix. Thus, the aim of this study was to compare the levels of the mRNA species coding for CRH, CRH-BP, CRH-R1 and CRH-R2 in human cervical tissue and myometrium at preterm and term labor and not in labor as well as in the non-pregnant state, and to localize the corresponding proteins employing immunohistochemical analysis.

METHODS

Cervical, isthmic and fundal (from non-pregnant subjects only) biopsies were taken from 67 women. Subjects were divided in 5 groups: preterm labor (14), preterm not in labor (7), term labor (18), term not in labor (21) and non-pregnant (7). Real-time RT-PCR was employed for quantification of mRNA levels and the corresponding proteins were localized by immunohistochemical analysis.

RESULTS

The levels of CRH-BP, CRH-R1 and CRH-R2 mRNA in the pregnant tissues were lower than those in non-pregnant subjects. No significant differences were observed between preterm and term groups. CRH-BP and CRH-R2 mRNA and the corresponding proteins were present at lower levels in the laboring cervix than in the non-laboring cervix, irrespective of gestational age. In most of the samples, with the exception of four myometrial biopsies the level of CRH mRNA was below the limit of detection. All of these proteins could be detected and localized in the cervix and the myometrium by immunohistochemical analysis.

CONCLUSION

Expression of CRH-BP, CRH-R1 and CRH-R2 in uterine tissues is down-regulated during pregnancy. The most pronounced down-regulation of CRH-BP and CRH-R2 occurred in laboring cervix, irrespective the length of gestation. The detection of substantial expression of the CRH and its receptor proteins, as well as receptor mRNA in the cervix suggests that the cervix may be a target for CRH action. Further studies are required to elucidate the role of CRH in cervical ripening.

Non-infected preterm parturition is related to increased concentrations of IL-6, IL-8 and MCP-1 in human cervix

BACKGROUND

Human cervical ripening is an inflammatory process. In labour at term the mRNA-levels and protein concentrations for interleukin-6 (IL-6) and IL-8 in cervix significantly increase. The aim of this study was to investigate if there are differences in the inflammatory process of preterm and term cervical ripening.

METHODS

Cervical biopsies from 50 singleton pregnant women without clinical signs of infection were allocated to four groups: preterm labour, term labour, preterm not in labour and term not in labour. The protein levels of IL-8, IL-6, monocyte chemotactic protein-1 (MCP-1), regulated upon activation normal t cells expressed and secreted (RANTES) and tumour necrosis factor-alpha (TNF-alpha) were quantified in tissue homogenates by ELISA or Immulite. The mRNA expression of IL-8, MCP-1 and RANTES was studied using RT-PCR. White blood cell count (WBC) and C-reactive protein (CRP) in the blood were determined. For determination of statistically significant differences between study groups Mann-Whitney U test or Kruskal-Wallis test were applied.

RESULTS

Protein concentrations of IL-8, IL-6, and MCP-1 were significantly increased during labour compared to non-labouring groups, whereas no changes were observed for RANTES and TNF-alpha. The mRNA levels of representative cytokines such as IL-8 and MCP-1 increased significantly during labour whereas RANTES mRNA expression remained unchanged. WBC and CRP were significantly higher in the labouring groups as compared to groups not in labour. For neither of the analysed cytokines, WBC or CRP levels were there any changes between preterm and term respective groups.

CONCLUSION

Our findings indicate that non-infected preterm cervical ripening is an inflammatory process, just as cervical ripening at term, with cytokines as important mediators.

Mode of delivery in pregnant women with hypertensive disorders and unfavorable cervix following induction of labor with vaginal application of prostaglandin E

BACKGROUND

Our aim was to evaluate the mode of delivery in pregnant women with hypertensive disorders and unfavorable cervix following induction of labor with vaginal application of prostaglandin E(2) (PGE(2)) near or at term, and to define the predictors of successful vaginal delivery in such women.

METHODS

In a retrospective case-controlled study, pregnant women with hypertension, who underwent labor induction with PGE(2) tablets (study group, n = 284), were compared with women, who underwent elective induction of labor (group 2, n = 115), and women with normal spontaneous onset of labor (group 3, n = 510).

RESULTS

The rate of cesarean section (CS) was significantly higher in the study group (25.3%) than in group 2 (14.8%) and in group 3 (9%). Exclusion of the nulliparous women from the study and control groups yielded similar CS rates in the study group (16.9%) and in group 2 (11.1%). Women with pre-eclampsia and the women with chronic hypertension or pregnancy-induced hypertension had similar rates of CS. In logistic regression model, nulliparity, induction of labor with PGE(2), and maternal age, but not hypertensive disorders, were independently and significantly associated with increased risk of CS.

CONCLUSIONS

PGE(2) induction of labor is successful in approximately 75% of patients with hypertensive disorders and unfavorable cervix, with apparently no serious maternal or fetal complications. The induction of labor by itself, and not the hypertensive disorders in pregnancy, is independent risk factor for CS.

Induction of labour with an unfavourable cervix

Labour induction is undertaken when the advantages for the mother and/or the baby are considered to outweigh the disadvantages. When the uterine cervix is unfavourable, oxytocin, with or without amniotomy, is frequently ineffective. Vaginal prostaglandin E(2) is most commonly used if it is affordable. Evidence regarding many alternative methods is discussed in this chapter. Of particular interest are misoprostol and extra-amniotic saline infusion.Misoprostol, an orally active prostaglandin E(1) analogue, has been used widely by the vaginal and oral routes for labour induction at or near term. Several recent trials have confirmed that it is highly effective. Overall Caesarean section rates appear to be reduced, despite a relative increase in Caesarean sections for fetal heart rate abnormalities. Concern remains regarding increased rates of uterine hyperstimulation and meconium-stained amniotic fluid, although data on perinatal outcome have been reassuring. Postpartum haemorrhage may be increased following labour induction with misoprostol, and isolated reports of uterine rupture, with or without previous Caesarean section, have appeared. Using small dosages appears to reduce adverse outcomes. Very large trials are needed to evaluate rare adverse outcomes.Extra-amniotic saline infusion is an effective method which appears to reduce the risk of uterine hyperstimulation that occurs with the use of exogenous uterotonics.