Development of progesterone electrospun nanofibers to coat Arabin pessaries as a dual preventive and therapeutic approach for preterm labor

Preterm labor is a growing health problem that causes newborn death, and safe and effective therapy is significantly needed. Arabin pessaries and progesterone are preventive and therapeutic approaches that can be applied to managing the short cervix; hence, reducing the risk of preterm labor. The main goal of current work is to fabricate a novel nanofiber formulation based on polycaprolactone (PCL) and loaded with progesterone to coat for Arabin pessaries to be used as dual preventive and therapeutic approaches for local vaginal delivery. Several important criteria were considered in this study to assess the prepared nanofibers (i.e.; nanofiber diameter, progesterone loading efficiency, progesterone release profiles and in vitro cytotoxicity assessment). The results showed a dimeter of 397 ± 88 nm, drug loading of 142 ± 3 µg/mg and encapsulation efficiency of 99 ± 2 % for the progesterone-loaded nanofibers. Approximately, 17 % of progesterone was released from the nanofibers after 90 days. The in vitro assessment showed that the application of progesterone is safe upon 24 and 48-hours incubation on HFF-1 cell line at concentrations ≤ 32 µg/mL and within 72-hours at a dose of ≤ 8 µg/mL. To conclude, the data recommended that progesterone-loaded nanofibers can coat the Arabin pessaries with the potential of being a safe and effective dual preventive and therapeutic tool for preterm labor.

Progestogen maintenance therapy for prolongation of pregnancy after an episode of preterm labour: A systematic review and meta-analysis

BACKGROUND

Evidence for progestogen maintenance therapy after an episode of preterm labour (PTL) is contradictory.

OBJECTIVES

To assess effectiveness of progestogen maintenance therapy after an episode of PTL.

SEARCH STRATEGY

An electronic search in Central Cochrane, Ovid Embase, Ovid Medline and clinical trial databases was performed.

SELECTION CRITERIA

Randomised controlled trials (RCT) investigating women between 16+0 and 37+0  weeks of gestation with an episode of PTL who were treated with progestogen maintenance therapy compared with a control group.

DATA COLLECTION AND ANALYSIS

Systematic review and meta-analysis were conducted. The primary outcome was latency time in days. Secondary neonatal and maternal outcomes are consistent with the core outcome set for preterm birth studies. Studies were extensively assessed for data trustworthiness (integrity) and risk of bias.

MAIN RESULTS

Thirteen RCT (1722 women) were included. Progestogen maintenance therapy demonstrated a longer latency time of 4.32 days compared with controls (mean difference [MD] 4.32, 95% CI 0.40-8.24) and neonates were born with a higher birthweight (MD 124.25 g, 95% CI 8.99-239.51). No differences were found for other perinatal outcomes. However, when analysing studies with low risk of bias only (five RCT, 591 women), a significantly longer latency time could not be shown (MD 2.44 days; 95% CI -4.55 to 9.42).

CONCLUSIONS

Progestogen maintenance therapy after PTL might have a modest effect on prolongation of latency time. When analysing low risk of bias studies only, this effect was not demonstrated. Validation through further research, preferably by an individual patient data meta-analysis is highly recommended.

Progestogens for maintenance tocolysis in symptomatic women. A systematic review and meta-analysis

OBJECTIVE

Prevention of preterm birth (PTB) with progestogens after an episode of threatened preterm labour is still controversial. As different progestogens have distinct molecular structures and biological effects, we conducted a systematic review and pairwise meta-analysis to investigate the individual role played by 17-alpha-hydroxyprogesterone caproate (17-HP), vaginal progesterone (Vaginal P) and oral progesterone (Oral P).

METHODS

The search was performed in MEDLINE, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials (CENTRAL) up to 31 October 2021. Published RCTs comparing progestogens to placebo or no treatment for maintenance tocolysis were considered. We included women with singleton gestations, excluding quasi-randomized trials, studies on women with preterm premature rupture of membrane, or receiving maintenance tocolysis with other drugs. Primary outcomes were preterm birth (PTB) < 37 weeks' and < 34 weeks'. We assessed risk of bias and evaluated certainty of evidence with the GRADE approach.

RESULTS

Seventeen RCTs including 2152 women with singleton gestations were included. Twelve studies tested vaginal P, five 17-HP, and only 1 oral P. PTB < 34 weeks' did not differ among women receiving vaginal P (RR 1.21, 95%CI 0.91 to 1.61, 1077 participants, moderate certainty of evidence), or oral P (RR 0.89, 95%CI 0.38 to 2.10, 90 participants, low certainty of evidence) as opposed to placebo. Instead, 17-HP significantly reduced the outcome (RR 0.72, 95% CI 0.54 to 0.95, 450 participants, moderate certainty of evidence). PTB < 37 weeks' did not differ among women receiving vaginal P (RR 0.95, 95%CI 0.72 to 1.26, 8 studies, 1231 participants, moderate certainty of evidence) or 17-HP (RR 0.86, 95%CI 0.60 to 1.21, 450 participants, low certainty of evidence) when compared to placebo/no treatment. Instead, oral P significantly reduced the outcome (RR 0.58, 95% CI 0.36 to 0.93, 90 participants, low certainty of evidence).

CONCLUSIONS

With a moderate certainty of evidence, 17-HP prevents PTB < 34 weeks' gestation among women that remained undelivered after an episode of threatened preterm labour. However, data are insufficient to generate recommendations in clinical practice. In the same women, both 17-HP and vaginal P are ineffective in the prevention of PTB < 37 weeks'.

Progesterone Gel and Placebo Prolonged Pregnancy More Effectively Than Intravenous Tocolysis Alone in Women with Preterm Labor

The aim of this trial was to evaluate the effect of progesterone gel compared to placebo in prolonging pregnancy among women with preterm labor. Methods: A randomized controlled trial in Sweden in 2009−18. Women with early preterm labor were randomized to daily doses of progesterone gel 90 mg (n = 28) or placebo (n = 30) after standard intravenous tocolytics. Women with intravenous tocolytics alone (n = 29) served as controls. Results: The median latency to delivery was 68 (range 28−88) days with progesterone and 72 (range 9−90) days with placebo (p = 0.84), compared to 1 (range 1−2) day in the control group (progesterone and placebo vs. control p < 0.001). The rate of preterm birth before 34 weeks was 32% after progesterone and 37 % after placebo (p = 0.32) compared to 100 % in the control group (p < 0.001, respectively). The composite neonatal morbidity (p = 0.65) and neonatal intensive care unit admission (p = 0.12) were comparable between the progesterone and placebo groups and lower in these groups compared with neonates in the control group (p < 0.001, respectively). Conclusions: Progesterone gel and placebo were equally effective in prolonging pregnancy among women with early preterm labor, and both treatments were more effective than standard intravenous tocolysis alone. We hypothesize that the acidic placebo gel reinforced the biochemical barrier at the uterine cervix, which counteracts ascending pathogen invasion and subsequent inflammation, and thereby prevented preterm labor.

Vaginal progesterone for preterm birth prevention in women with arrested preterm labor

OBJECTIVE

We tested the hypothesis that administration of vaginal progesterone in women with arrested preterm labor would result in lower rates of preterm birth <37 weeks compared to placebo.

STUDY DESIGN

We performed a randomized, placebo-controlled trial comparing vaginal progesterone to placebo in women with arrested preterm labor. Our trial included women with a singleton or twin gestation at 24^0/7-33^6/7 weeks' gestation who presented with preterm labor with cervical dilation ≥1 centimeter but remained undelivered. Participants were randomized to receive vaginal progesterone 200 mg daily or an identical placebo. The primary outcome was preterm birth <37 weeks. We performed an updated systematic review and meta-analysis of clinical trials, including our results. We searched MEDLINE, EMBASE, CINHAL, Scopus, the Cochrane Database of Systematic Reviews, and ClinicalTrials.gov using the key terms to identify relevant trials. The risk of bias was appraised using the Cochrane risk-of-bias tool. Data were synthesized using random-effects models. Heterogeneity was assessed using Higgins I².

RESULTS

The randomized trial was prematurely terminated due to slow recruitment. There were 18 women randomized to receive vaginal progesterone who had complete follow-up data and 18 women in the placebo group. The risk of preterm birth <37 weeks was not significantly different in the groups (RR 1.10, 95% CI 0.63-1.19). Secondary outcomes were also similar. Thirteen trials with 1658 women (835 in the vaginal progesterone and 823 in the control groups) were included in the meta-analysis. Risk of preterm birth <37 weeks was similar in women who received progesterone and those in the control group (pooled RR 1.06, 95% CI 0.83-1.35). Latency was significantly longer among women with arrested preterm labor who received vaginal progesterone (weighted mean difference: 9.2 d, 95% CI 3.2-15.1), but further analysis showed that prolonged latency was only observed in the subgroup of studies that were not placebo-controlled.

CONCLUSIONS

This randomized controlled trial and meta-analysis do not support the use of vaginal progesterone for the prevention of preterm birth in women who present in preterm labor.

Vaginal Progesterone Supplementation in the Management of Preterm Labor: A Randomized Controlled Trial

OBJECTIVES

The primary objective in this study was to evaluate the effects of vaginal progesterone supplementation for the prolongation of the latency period in preterm labor. The secondary objectives were to evaluate gestational age at delivery, rates of preterm birth less than 34 and 37 weeks, obstetric outcomes, maternal compliance with medication use, and side effects.

METHODS

A randomized controlled, unblinded trial was performed. Ninety women with preterm labor occurring at 24 to 34 weeks were either randomized to a vaginal progesterone group (44 women) receiving tocolytic and antenatal corticosteroids treatment combined with vaginal micronized progesterone (400 mg everyday) or to the no-progesterone group (46 women) receiving tocolytic and antenatal corticosteroids treatment only.

RESULTS

Latency periods were more prolonged in the vaginal progesterone group than in the no-progesterone group (32.8 ± 18.7 vs. 25.8 ± 22.7 days, p = 0.045). Gestational age at delivery in the vaginal progesterone group was also higher than in the no-progesterone group (37 vs. 35 weeks, p = 0.027). There were significant reduction rates of preterm birth less than 34 weeks (13.6% vs. 39.1%, p = 0.012), low birth weight (29.5% vs. 50%, p = 0.048), neonatal respiratory distress syndrome (13.6% vs. 37%, p = 0.021), and neonatal intensive care unit admission (6.8% vs. 28.3%, p = 0.017).

CONCLUSIONS

Combined treatment with vaginal progesterone 400 mg could prolong the latency period in preterm labor when compared with no progesterone.

Oral dydrogesterone as an adjunctive therapy in the management of preterm labor: a randomized, double blinded, placebo-controlled trial

BACKGROUND

Preterm birth is a major challenge in obstetric and perinatal care. It is the leading cause of neonatal death. The primary aim of this study was to evaluate the efficacy of oral dydrogesterone on latency period in managing preterm labor. The secondary aims were to evaluate the gestational age at delivery, percentage of preterm delivery before 34 weeks and 37 weeks, time to recurrent uterine contraction, pregnancy outcomes, neonatal outcomes, compliance and side effects.

METHODS

This was a randomized, double blinded, placebo-controlled trial. Forty-eight pregnant women with preterm labor, singleton pregnancy, and gestational age of 24-34 weeks were enrolled into the study. The study group received 10 mg of oral dydrogesterone three times per day and the control group received placebo. All pregnant women received standard treatment with tocolytic and antenatal corticosteroids.

RESULTS

The median latency periods were not significantly different between the dydrogesterone group (27.5 days) and placebo group (34 days, p = 0.45). Additionally, there were no differences in the gestational age at delivery, percentage of preterm delivery before 34 weeks and 37 weeks, pregnancy outcomes, neonatal outcomes, compliance and side effects. However, the time to the recurrence of uterine contractions in participants that had recurrent preterm labor was longer in the dydrogesterone group than in the placebo group (30.6 ± 12.3 vs 13.7 ± 5.0 days, p = 0.01).

CONCLUSIONS

Adjunctive treatment with 30 mg of oral dydrogesterone could not prolong latency period in preterm labor when compared to placebo.

TRIAL REGISTRATION

ClinicalTrials.gov (Clinical trials registration: NCT03935152 , registered on May 2,2019).

The use of vaginal progesterone as a maintenance therapy in women with arrested preterm labor: a double-blind placebo-randomized controlled trial

Background: The efficacy of maintenance tocolytic therapy after successful arrest of preterm labor remains controversial. The purpose of this study was to evaluate the efficacy of 400 mg of daily vaginal progesterone (cyclogest) after successful parenteral tocolysis to increase latency period and improvement of neonatal outcomes in women with threatened preterm labor.Materials and methods: In this randomized, double-blind, placebo-controlled trial, 85 participants were randomly allocated to either 400 mg daily of vaginal progesterone (n = 45) or placebo (n = 40) until 34 weeks of gestation. The primary outcomes were the time until delivery (latency period) and cervical length after 1 week of treatment. Secondary outcome were GA on delivery, type of delivery, incidence of low birth weight, perinatal morbidity and mortality.Results: Longer mean latency until delivery (53.6 ± 16.8 versus 34.5 ± 12.9) days p = .0001; longer mean of gestational age on delivery (37.5 ± 2.2 versus 34.2 ± 2.1) weeks p = .0001; cervical length after 1 week of treatment (27.5 ± 5.5 versus 20.7 ± 3.1) mm p = .0001; low birth weight 12 (29.3%) versus 19 (57.6%) p = .01; and NICU admission 9 (22%) versus 15 (45.5%), were significantly different between the two groups. No significant differences were found between neonatal death 1 (2.4%) versus 2 (6.1%), p = .43; RDS 5 (12.2%) versus 8 (24.2%), p = .17; and need to mechanical ventilator 2 (5.4%) versus 6 (18.2%) p = .136, for the progesterone and placebo groups, respectively.Conclusion: Daily administration of 400 mg vaginal progesterone after successful parenteral tocolysis may increase latency preceding delivery and improves cervical shortening and neonatal outcome in women with preterm labor. Further confirmatory studies are warranted.

Progesterone - Effective for Tocolysis and Maintenance Treatment After Arrested Preterm Labour?: Critical Analysis of the Evidence

Numerous experimental studies indicate that natural progesterone, through various mechanisms, exerts an inhibitory effect on uterine contractility and sensitises the myometrium for tocolytics. It was therefore appropriate to investigate the possible benefits of oral/vaginal progesterone and the synthetic progesterone derivative 17-α-hydroxyprogesterone caproate, applied intramuscularly, in clinical studies on primary tocolysis, additively to established tocolytics ("adjunctive tocolysis") and as maintenance treatment after successful tocolysis in cases of threatened preterm birth. Three studies with a small number of cases do not yield any sufficient evidence for recommending progesterone/17-α-hydroxyprogesterone caproate as primary tocolysis in women with preterm labour. There is also no evidence that progesterone or 17-α-hydroxyprogesterone caproate combined with commonly used tocolytics leads to a prolongation of pregnancy and a significant decrease in the rate of preterm birth. The data on the use of progesterone as maintenance treatment is controversial. While randomised, controlled studies with low quality showed promising results, studies with high quality did not reveal any significant differences with regard to the rate of preterm birth < 37 weeks of gestation, the latency period until delivery and in the neonatal outcome between progesterone/17-α-hydroxyprogesterone caproate and placebo or no treatment. Significant differences in the methodology, the inclusion and outcome criteria, the mode of application and the dosages of the substances as well as the inadequate statistical power as a result of low numbers of cases make interpretation and comparability of the studies difficult. Therefore, well-designed randomised, placebo-controlled, double-blind studies with uniform primary outcome criteria are needed in order to clarify whether progesterone and via which route of administration and at which dosage is of clinical benefit for patients with manifest preterm contractions and as maintenance treatment after arrested preterm labour.

Progesterone as a tocolytic agent for preterm labor: a systematic review

PURPOSE OF REVIEW

Tocolytic agents have been used for over 60 years in the fight against preterm labor, which ultimately can lead to preterm birth. Currently, clinicians can choose from a variety of drug classes to achieve the primary goal of delaying delivery by 48 h, thereby allowing time for administration of corticosteroids for fetal lung maturity, and if appropriate, starting magnesium sulfate for fetal neuroprotection. However, there are currently no known therapies to maintain the tocolytic effect beyond those initial 48 h.

RECENT FINDINGS

Progesterone, which has been used in the prevention of preterm birth for over 10 years, has long been known to have the effect of uterine quiescence. It was first studied as a tocolytic agent in the 1960s. In the last several years, more studies have been done that suggest a potential use for maintenance tocolysis after the successful arrest of preterm labor. Although the studies are conflicting, the meta-analyses on progesterone show some promise in different outcomes of delayed delivery, reduced incidence of preterm birth, and reduced neonatal morbidity.

SUMMARY

Progesterone is currently the most promising agent for maintenance tocolysis. Although further trials are certainly needed, this is an exciting advancement in the realm of tocolysis.

Use of progesterone supplement therapy for prevention of preterm birth: review of literatures

Preterm birth (PTB) is one of the most common complications during pregnancy and it primarily accounts for neonatal mortality and numerous morbidities including long-term sequelae including cerebral palsy and developmental disability. The most effective treatment of PTB is prediction and prevention of its risks. Risk factors of PTB include history of PTB, short cervical length (CL), multiple pregnancies, ethnicity, smoking, uterine anomaly and history of curettage or cervical conization. Among these risk factors, history of PTB, and short CL are the most important predictive factors. Progesterone supplement therapy is one of the few proven effective methods to prevent PTB in women with history of spontaneous PTB and in women with short CL. There are 2 types of progesterone therapy currently used for prevention of PTB: weekly intramuscular injection of 17-alpha hydroxyprogesterone caproate and daily administration of natural micronized progesterone vaginal gel, vaginal suppository, or oral capsule. However, the efficacy of progesterone therapy to prevent PTB may vary depending on the administration route, form, dose of progesterone and indications for the treatment. This review aims to summarize the efficacy and safety of progesterone supplement therapy on prevention of PTB according to different indication, type, route, and dose of progesterone, based on the results of recent randomized trials and meta-analysis.

A randomized, double blinded, placebo controlled trial of oral dydrogesterone supplementation in the management of preterm labor

The primary aim of this study was to evaluate the effect of oral dydrogesterone on the recurrent uterine contraction in preterm labor. The secondary aims were to evaluate latency period, gestational age at delivery, pregnancy outcomes, neonatal outcomes, compliance and side effects. A randomized, double blinded, placebo controlled trial was conducted. Forty-eight pregnant women at 24-34 weeks gestation with preterm labor were either randomized to study group receiving tocolytic treatment combined with oral dydrogesterone (20 mg daily) or to placebo group receiving tocolytic treatment combined with oral placebo. Recurrent rates of uterine contraction were comparable between groups (87.5% vs 91.7%, p = 0.64). Latency periods were not different between dydrogesterone and placebo group (32.7 ± 20.2 days vs 38.2 ± 24.2 days, p = 0.39). There were also no differences in gestational age at delivery, pregnancy outcomes, neonatal outcomes, compliance and side effects. Adjuvant treatment with oral dydrogesterone 20 mg/day could not decrease the rates of recurrent uterine contraction and prolong latency period in preterm labor management when compared to placebo.

Vaginal progesterone for maintenance tocolysis: a systematic review and metaanalysis of randomized trials

OBJECTIVE

We sought to evaluate the efficacy of maintenance tocolysis with vaginal progesterone compared to control (placebo or no treatment) in singleton gestations with arrested preterm labor (PTL) in a metaanalysis of randomized controlled trials.

STUDY DESIGN

Searches were performed in MEDLINE, OVID, Scopus, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials with the use of a combination of key words and text words related to "progesterone," "tocolysis," and "preterm labor" from 1966 through November 2014. We included all randomized trials of singleton gestations that had arrested PTL and then were randomized to maintenance tocolysis treatment with either vaginal progesterone or control (either placebo or no treatment). All published randomized studies on progesterone tocolysis were carefully reviewed. Exclusion criteria included maintenance tocolysis in women with preterm premature rupture of membrane, maintenance tocolysis with 17-alpha-hydroxyprogesterone caproate, and maintenance tocolysis with oral progesterone. The summary measures were reported as relative risks (RRs) with 95% confidence interval (CI). The primary outcome was preterm birth (PTB) <37 weeks.

RESULTS

Five randomized trials, including 441 singleton gestations, were analyzed. Women who received vaginal progesterone maintenance tocolysis for arrested PTL had a significantly lower rate of PTB <37 weeks (42% vs 58%; RR, 0.71; 95% CI, 0.57-0.90; 3 trials, 298 women). Women who received vaginal progesterone had significantly longer latency (mean difference 13.80 days; 95% CI, 3.97-23.63; 4 trials, 368 women), later gestational age at delivery (mean difference 1.29 weeks; 95% CI, 0.43-2.15; 4 trials, 368 women), lower rate of recurrent PTL (24% vs 46%; RR, 0.51; 95% CI, 0.31-0.84; 2 trials, 122 women), and lower rate of neonatal sepsis (2% vs 7%; RR, 0.34; 95% CI, 0.12-0.98; 4 trials, 368 women).

CONCLUSION

Maintenance tocolysis with vaginal progesterone is associated with prevention of PTB, significant prolongation of pregnancy, and lower neonatal sepsis. However, given the frequent lack of blinding and the generally poor quality of the trials, we do not currently suggest a change in clinical care of women with arrested PTL. We suggest instead well-designed placebo-controlled randomized trials to confirm the findings of our metaanalysis.

17-alpha-hydroxyprogesterone caproate for maintenance tocolysis: a systematic review and metaanalysis of randomized trials

We sought to evaluate the efficacy of maintenance tocolysis with 17-alpha-hydroxyprogesterone caproate (17P) compared to control (either placebo or no treatment) in singleton gestations with arrested preterm labor (PTL), in a metaanalysis of randomized trials. Electronic databases (MEDLINE, OVID, Scopus, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials) were searched from 1966 through July 2014. Key words included "progesterone," "tocolysis," "preterm labor," and "17-alpha-hydroxyprogesterone caproate." We performed a metaanalysis of randomized trials of singleton gestations with arrested PTL and treated with maintenance tocolysis with either 17P or control. Primary outcome was preterm birth (PTB) <37 weeks. This metaanalysis was performed following the Preferred Reporting Items for Systematic Reviews and Metaanalyses (PRISMA) statement. The protocol was registered with PROSPERO (registration no: CRD42014013473). Five randomized trials met inclusion criteria, including 426 women. Women with a singleton gestation who received 17P maintenance tocolysis for arrested PTL had a similar rate of PTB <37 weeks (42% vs 51%; relative risk [RR], 0.78; 95% confidence intervals [CI], 0.50-1.22) and PTB <34 weeks (25% vs 34%; RR, 0.60; 95% CI, 0.28-1.12) compared to controls. Women who received 17P had significantly later gestational age at delivery (mean difference, 2.28 weeks; 95% CI, 1.46-13.51), longer latency (mean difference, 8.36 days; 95% CI, 3.20-13.51), and higher birthweight (mean difference, 224.30 g; 95% CI, 70.81-377.74) as compared to controls. Other secondary outcomes including incidences of recurrent PTL, neonatal death, admission to neonatal intensive care unit, neonatal respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and neonatal sepsis were similar in both groups. Maintenance tocolysis with 17P after arrested PTL is not associated with prevention of PTB compared to placebo or no treatment in a metaanalysis of the available randomized trials. As 17P for maintenance tocolysis is associated with a significant prolongation of pregnancy, and significantly higher birthweight, further research is suggested.

Combination of tocolytic agents for inhibiting preterm labour

BACKGROUND

Preterm birth represents the single largest cause of mortality and morbidity for newborns and a major cause of morbidity for pregnant women. Tocolytic agents include a wide range of drugs that can inhibit labour to prolong pregnancy. This may gain time to allow the fetus to mature further before being born, permit antenatal corticosteroid administration for lung maturation, and allow time for intra-uterine transfer to a hospital with neonatal intensive care facilities. However, some tocolytic drugs are associated with severe side effects. Combinations of tocolytic drugs may be more effective over single tocolytic agents or no intervention, without adversely affecting the mother or neonate.

OBJECTIVES

To assess the effects on maternal, fetal and neonatal outcomes of any combination of tocolytic drugs for the treatment of preterm labour when compared with any other treatment, no treatment or placebo.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials comparing a combination of tocolytic agents, administered by any route or any dose, for inhibiting preterm labour versus any other treatment (including other combinations of tocolytics or single tocolytics), no intervention or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study reports for eligibility, carried out data extraction and assessed risk of bias.

MAIN RESULTS

Eleven studies met our inclusion criteria. Two studies did not report any outcome data relevant to the review, so the results of the review are based on nine trials that contributed data. Primary outcomes were perinatal mortality, serious maternal or infant outcomes, adverse drug reactions, birth before 48 hours of trial entry, birth before 34 weeks' gestation and preterm neonates delivered without a full course of antenatal steroids completed 24 hours before birth. The quality of evidence in included trials was mixed; only three of the trials were placebo controlled.The included trials examined seven different comparisons: intravenous (IV) ritodrine plus oral or IV magnesium (sulphate or gluconate) versus IV ritodrine alone (three trials, 231 women); IV ritodrine plus indomethacin suppositories versus IV ritodrine alone (one trial, 208 women); IV ritodrine plus vaginal progesterone versus IV ritodrine alone (one trial, 83 women); IV hexoprenaline sulphate plus IV magnesium hydrochloride versus IV hexoprenaline sulphate alone (one trial, 24 women); IV fenoterol plus oral naproxen versus IV fenoterol alone (one trial, 72 women); oral pentoxifylline plus IV magnesium sulphate plus IV fenoterol versus IV magnesium sulphate plus IV fenoterol (one trial, 125 women); and, IV terbutaline plus oral metoprolol versus IV terbutaline alone (one trial, 17 women). Few studies with small numbers of women were available for each comparison, hence very little data were pooled in meta-analysis. In all trials, not many of the primary outcomes were reported.Three trials examined intravenous (IV) ritodrine plus IV or oral magnesium (sulphate or gluconate) compared with IV ritodrine alone. One study, with 41 women, reported more adverse drug reactions in the group receiving the combined tocolytics (risk ratio (RR) 7.79, 95% confidence interval (CI) 1.11 to 54.80). Two trials reported discontinuation of therapy due to severe side effects (results were not combined due to high statistical heterogeneity, I² = 83%); one trial reported increased severe side effects in the group receiving IV ritodrine alone (RR 7.79, 95% CI 1.11 to 54.80, 41 women); in the other trial there was no clear difference between groups (RR 0.23, 95% CI 0.03 to 1.97, 107 women). Other primary outcomes were not reported.One trial assessed IV ritodrine plus indomethacin suppositories versus IV ritodrine alone. There were no significant differences between groups for perinatal mortality or serious neonatal morbidity. Results for other primary outcomes were not reported.There were no significant differences between groups receiving IV ritodrine plus vaginal progesterone compared with IV ritodrine alone for most outcomes reported, although the latency period (time from recruitment to delivery) was increased in the group receiving the combination of tocolytics.For other combinations of tocolytic agents, primary outcomes were rarely reported and for secondary outcomes results did not demonstrate differences between groups.

AUTHORS' CONCLUSIONS

It is unclear whether a combination of tocolytic drugs for preterm labour is more advantageous for women and/or newborns due to a lack of large, well-designed trials including the outcomes of interest. There are no trials of combination regimens using widely used tocolytic agents, such as calcium channel blockers (nifedipine) and/or oxytocin receptor antagonists (atosiban). Further trials are needed before specific conclusions on use of combination tocolytic therapy for preterm labour can be made.

Maintenance tocolysis with oral micronized progesterone for prevention of preterm birth after arrested preterm labor

OBJECTIVE

To evaluate the efficacy of maintenance therapy with oral micronized progesterone (OMP) for prolongation of pregnancy in cases of arrested preterm labor.

METHODS

Ninety women at 24-34weeks of singleton pregnancy with intact membranes and arrested preterm labor were randomly allocated to receive OMP (n=45) or placebo (n=45) daily until 37weeks or delivery, whichever was earlier. Outcome parameters were compared using Student t test, χ(2) test, Fisher exact test, and log-rank χ(2) test.

RESULTS

OMP significantly prolonged the latency period (33.29±22.16 vs 23.07±15.42days; P=0.013). Log-rank analysis revealed a significant difference in mean time to delivery between the 2 groups (P=0.014). There were significantly fewer preterm births (33% vs 58%; P=0.034) and low birth weight neonates (37% vs 64%; P=0.017), and significantly higher mean birth weight (2.44±0.58 vs 2.14±0.47kg; P=0.009) in the OMP group. Perinatal outcomes and adverse effects were similar in the 2 groups.

CONCLUSION

Maintenance tocolysis with OMP significantly prolonged pregnancy and decreased the number of preterm births. Clinical Trial Registry of India: CTRI/2011/10/002043.

Preterm labor: current pharmacotherapy options for tocolysis

INTRODUCTION

In the developed world, preterm birth is in quantity and in severity the most important issue in obstetric care. Adverse neonatal outcome is strongly related to gestational age at delivery. Since the pathophysiological mechanism of preterm birth is not yet completely unraveled, the development of successful preventive strategies is hampered. When preterm labor is actually threatening, current pharmacological therapies focus on inhibition of preterm contractions. This allows for transportation of the mother to a center with a neonatal intensive care unit and administration of corticosteroids to enhance fetal lung maturation. Globally, however, large practice variation exists.

AREAS COVERED

The aim of this review is to provide an overview of current pharmacological therapies for preterm labor.

EXPERT OPINION

For the initial tocolysis, the use of atosiban or nifedipine for 48 h is recommended based on the largest effectiveness and most favorable side effect profile. However, since data that convincingly indicate the beneficial effect of tocolytics on neonatal outcome are lacking, it might well be that tocolytics are ineffective. The role of progesterone in treatment of acute tocolysis is limited, but it might play a role in the prevention of preterm labor or as sensitizer for other tocolytic agents.

Progestational agents for treating threatened or established preterm labour

BACKGROUND

Prematurity is not only the leading cause of perinatal morbidity and mortality but is associated with long-term impairment. Studies of various tocolytic agents have shown mixed results with little effect in improving pregnancy duration and insufficient data to confirm a definite beneficial effect on neonatal morbidity or mortality. Progesterone is known to have an inhibitory effect on uterine contractility and is thought to play a key role in the maintenance of pregnancy until term.

OBJECTIVES

To determine if the use of progestational agents is effective as a form of treatment or co-treatment for women with threatened or established preterm labour with intact membranes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2013), CENTRAL (The Cochrane Library 2013, Issue 10), MEDLINE (1966 to August 31 2013) and Embase (1974 to 31 August 2013). We checked the reference lists of all included studies to identify any additional studies and communicated with authors and the pharmaceutical industry.

SELECTION CRITERIA

Randomised controlled trials that compared progestational agents, given either alone or in combination with other tocolytics, with a control group receiving another tocolytic, placebo or no treatment, for the treatment of preterm labour.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality.

MAIN RESULTS

Eight studies were included in this review, involving 563 women, but only seven studies, involving 538 women, contributed data for analyses. There are some data suggesting that the use of progestational agents results in a reduction of preterm deliveries at less than 37 weeks of gestation and an increase in birthweight. The use of a progestational agent may also reduce the frequency of uterine contractions, prolong pregnancy and attenuate the shortening of cervical length. However, the analysis was limited by the relatively small number of available studies. The power of the meta-analysis was also limited by the varying types, dosages and routes of administration of progesterone.

AUTHORS' CONCLUSIONS

There is insufficient evidence to advocate progestational agents as a tocolytic for women presenting with preterm labour.

Prevention of periviable birth: bed rest, tocolysis, progesterone, and cerclage

The periviable period is associated with a rapid improvement in both mortality and morbidity with increasing gestational age. Therapies that can prolong gestation have the potential for markedly improving outcome compared to later in pregnancy. The therapies commonly prescribed in order to prolong gestation include bed rest, tocolysis, progesterone, and cerclage. Although these therapies are used to prevent preterm birth throughout gestation, their impact on perinatal outcome during the periviable period remains largely unknown. These therapies are discussed relative to the periviable period exploring available data and possible impact on perinatal outcome. Studies specifically evaluating therapeutic interventions during the periviable period are lacking.

Prenatal administration of progesterone for preventing preterm birth in women considered to be at risk of preterm birth

BACKGROUND

Preterm birth is a major complication of pregnancy associated with perinatal mortality and morbidity. Progesterone for the prevention of preterm labour has been advocated.

OBJECTIVES

To assess the benefits and harms of progesterone for the prevention of preterm birth for women considered to be at increased risk of preterm birth and their infants.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (14 January 2013) and reviewed the reference list of all articles.

SELECTION CRITERIA

Randomised controlled trials, in which progesterone was given for preventing preterm birth.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated trials for methodological quality and extracted data.

MAIN RESULTS

Thirty-six randomised controlled trials (8523 women and 12,515 infants) were included. Progesterone versus placebo for women with a past history of spontaneous preterm birth Progesterone was associated with a statistically significant reduction in the risk of perinatal mortality (six studies; 1453 women; risk ratio (RR) 0.50, 95% confidence interval (CI) 0.33 to 0.75), preterm birth less than 34 weeks (five studies; 602 women; average RR 0.31, 95% CI 0.14 to 0.69), infant birthweight less than 2500 g (four studies; 692 infants; RR 0.58, 95% CI 0.42 to 0.79), use of assisted ventilation (three studies; 633 women; RR 0.40, 95% CI 0.18 to 0.90), necrotising enterocolitis (three studies; 1170 women; RR 0.30, 95% CI 0.10 to 0.89), neonatal death (six studies; 1453 women; RR 0.45, 95% CI 0.27 to 0.76), admission to neonatal intensive care unit (three studies; 389 women; RR 0.24, 95% CI 0.14 to 0.40), preterm birth less than 37 weeks (10 studies; 1750 women; average RR 0.55, 95% CI 0.42 to 0.74) and a statistically significant increase in pregnancy prolongation in weeks (one study; 148 women; mean difference (MD) 4.47, 95% CI 2.15 to 6.79). No differential effects in terms of route of administration, time of commencing therapy and dose of progesterone were observed for the majority of outcomes examined. Progesterone versus placebo for women with a short cervix identified on ultrasound Progesterone was associated with a statistically significant reduction in the risk of preterm birth less than 34 weeks (two studies; 438 women; RR 0.64, 95% CI 0.45 to 0.90), preterm birth at less than 28 weeks' gestation (two studies; 1115 women; RR 0.59, 95% CI 0.37 to 0.93) and increased risk of urticaria in women when compared with placebo (one study; 654 women; RR 5.03, 95% CI 1.11 to 22.78). It was not possible to assess the effect of route of progesterone administration, gestational age at commencing therapy, or total cumulative dose of medication. Progesterone versus placebo for women with a multiple pregnancy Progesterone was associated with no statistically significant differences for the reported outcomes. Progesterone versus no treatment/placebo for women following presentation with threatened preterm labour Progesterone, was associated with a statistically significant reduction in the risk of infant birthweight less than 2500 g (one study; 70 infants; RR 0.52, 95% CI 0.28 to 0.98). Progesterone versus placebo for women with 'other' risk factors for preterm birth Progesterone, was associated with a statistically significant reduction in the risk of infant birthweight less than 2500 g (three studies; 482 infants; RR 0.48, 95% CI 0.25 to 0.91).

AUTHORS' CONCLUSIONS

The use of progesterone is associated with benefits in infant health following administration in women considered to be at increased risk of preterm birth due either to a prior preterm birth or where a short cervix has been identified on ultrasound examination. However, there is limited information available relating to longer-term infant and childhood outcomes, the assessment of which remains a priority.Further trials are required to assess the optimal timing, mode of administration and dose of administration of progesterone therapy when given to women considered to be at increased risk of early birth.

Hormones in pregnancy

The endocrinology of human pregnancy involves endocrine and metabolic changes that result from physiological alterations at the boundary between mother and fetus. Progesterone and oestrogen have a great role along with other hormones. The controversies of use of progestogen and others are discussed in this chapter. Progesterone has been shown to stimulate the secretion of Th2 and reduces the secretion of Th1 cytokines which maintains pregnancy. Supportive care in early pregnancy is associated with a significant beneficial effect on pregnancy outcome. Prophylactic hormonal supplementation can be recommended for all assisted reproduction techniques cycles. Preterm labor can be prevented by the use of progestogen. The route of administration plays an important role in the drug's safety and efficacy profile in different trimesters of pregnancy. Thyroid disorders have a great impact on pregnancy outcome and needs to be monitored and treated accordingly. Method of locating review: Pubmed, scopus

Progestogens for preterm birth prevention: a systematic review and meta-analysis by drug route

PURPOSE

Progestogen has been investigated as a preventive intervention among women with increased preterm birth risk. Our objective was to systematically review the effectiveness of intramuscular (IM), vaginal, and oral progestogens for preterm birth and neonatal death prevention.

METHODS

We included articles published from January 1966 to January 2013 and found 27 randomized trials with data for Bayesian meta-analysis.

RESULTS

Across all studies, only vaginal and oral routes were effective at reducing preterm births (IM risk ratio [RR] 0.95, 95 % Bayesian credible interval [BCI]: 0.88-1.03; vaginal RR 0.87, 95 % BCI: 0.80-0.94; oral RR 0.64, 95 % BCI: 0.49-0.85). However, when analyses were limited to only single births all routes were effective at reducing preterm birth (IM RR 0.77, 95 % BCI: 0.69-0.87; vaginal RR 0.80, 95 % BCI: 0.69-0.91; oral RR 0.66, 95 % BCI: 0.47-0.84). Only IM progestogen was effective at reducing neonatal deaths (IM RR 0.78, 95 % BCI: 0.56-0.99; vaginal RR 0.75, 95 % BCI: 0.45-1.09; oral RR 0.72, 95 % BCI: 0.09-1.74). Vaginal progestogen was effective in reducing neonatal deaths when limited to singletons births.

CONCLUSIONS

All progestogen routes reduce preterm births but not neonatal deaths. Future studies are needed that directly compare progestogen delivery routes.

Vaginal progesterone vs. cervical cerclage for the prevention of preterm birth in women with a sonographic short cervix, previous preterm birth, and singleton gestation: a systematic review and indirect comparison metaanalysis

OBJECTIVE

No randomized controlled trial has compared vaginal progesterone and cervical cerclage directly for the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous spontaneous preterm birth. We performed an indirect comparison of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator.

STUDY DESIGN

Adjusted indirect metaanalysis of randomized controlled trials.

RESULTS

Four studies that evaluated vaginal progesterone vs placebo (158 patients) and 5 studies that evaluated cerclage vs no cerclage (504 patients) were included. Both interventions were associated with a statistically significant reduction in the risk of preterm birth at <32 weeks of gestation and composite perinatal morbidity and mortality compared with placebo/no cerclage. Adjusted indirect metaanalyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Based on state-of-the-art methods for indirect comparisons, either vaginal progesterone or cerclage are equally efficacious in the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous preterm birth. Selection of the optimal treatment needs to consider adverse events, cost and patient/clinician preferences.

Prenatal administration of progesterone for preventing preterm birth

BACKGROUND

Preterm birth is the major complication of pregnancy associated with perinatal mortality and morbidity and occurs in up to 6% to 10% of all births. Administration of progesterone for the prevention of preterm labour has been advocated.

OBJECTIVES

To assess the benefits and harms of progesterone administration during pregnancy in the prevention of preterm birth.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Specialised Register of Controlled Trials (March 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2004), MEDLINE (1965 to January 2005), EMBASE (1988 to August 2004), and Current Contents (1997 to August 2004).

SELECTION CRITERIA

All published and unpublished randomised controlled trials, in which progesterone was given by any route for preventing preterm birth.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group were used. Evaluation of methodological quality and trial data extraction were undertaken independently by two authors. Results are presented using relative risk with 95% confidence intervals.

MAIN RESULTS

For all women administered progesterone, there was a reduction in the risk of preterm birth less than 37 weeks (six studies, 988 participants, relative risk (RR) 0.65, 95% confidence interval (CI) 0.54 to 0.79) and preterm birth less than 34 weeks (one study, 142 participants, RR 0.15, 95% CI 0.04 to 0.64). Infants born to mothers administered progesterone were less likely to have birthweight less than 2500 grams (four studies, 763 infants, RR 0.63, 95% CI 0.49 to 0.81) or intraventricular haemorrhage (one study, 458 infants, RR 0.25, 95% CI 0.08 to 0.82). There was no difference in perinatal death between women administered progesterone and those administered placebo (five studies, 921 participants, RR 0.66, 95% CI 0.37 to 1.19). There were no other differences reported for maternal or neonatal outcomes.

AUTHORS' CONCLUSIONS

Intramuscular progesterone is associated with a reduction in the risk of preterm birth less than 37 weeks' gestation, and infant birthweight less than 2500 grams. However, other important maternal and infant outcomes have been poorly reported to date, with most outcomes reported from a single trial only (Meis 2003). It is unclear if the prolongation of gestation translates into improved maternal and longer-term infant health outcomes. Similarly, information regarding the potential harms of progesterone therapy to prevent preterm birth is limited. Further information is required about the use of vaginal progesterone in the prevention of preterm birth.