SMFM Statement: Use of 17-alpha hydroxyprogesterone caproate for prevention of recurrent preterm birth

Prediction and prevention of preterm birth: Quality assessment and systematic review of clinical practice guidelines using the AGREE II framework

BACKGROUND

Prediction of pregnancies at risk of preterm birth (PTB) may allow targeted prevention strategies.

OBJECTIVES

To assess quality of clinical practice guidelines (CPGs) and identify areas of agreement and contention in prediction and prevention of spontaneous PTB.

SEARCH STRATEGY

We searched for CPGs regarding PTB prediction and prevention in asymptomatic singleton pregnancies without language restriction in January 2024.

SELECTION CRITERIA

CPGs included were published between July 2017 and December 2023 and contained statements intended to direct clinical practice.

DATA COLLECTION AND ANALYSIS

CPG quality was assessed using the AGREE-II tool. Recommendations were extracted and grouped under domains of prediction and prevention, in general populations and high-risk groups.

MAIN RESULTS

We included 37 CPGs from 20 organizations; all were of moderate or high quality overall. There was consensus in prediction of PTB by identification of risk factors and cervical length screening in high-risk pregnancies and prevention of PTB by universal screening and treatment for asymptomatic bacteriuria, screening and treatment for BV in high-risk pregnancies, and use of preventative progesterone and cerclage. Areas of contention or limited consensus were the role of PTB clinics, universal cervical length measurement, biomarkers and cervical pessaries.

CONCLUSIONS

This review identified strengths and limitations of current PTB CPGs, and areas for future research.

Progesterone therapy for prevention of recurrent spontaneous preterm birth in a minority patient population: a retrospective study

BACKGROUND

Preterm birth is a leading cause of infant morbidity and mortality worldwide. The burden of prematurity underscores the need for effective risk reduction strategies. The purpose of this study is to evaluate the efficacy of progesterone therapy, both intramuscular 17-α-hydroxyprogesterone caproate (IM 17-OHPC) and vaginal progesterone, in the prevention of recurrent spontaneous preterm birth (sPTB). The co-primary outcomes included: recurrent spontaneous PTB < 37 and < 34 weeks' gestation.

METHODS

This retrospective cohort study included 637 pregnant patients that delivered at any of the three hospitals within the Los Angeles County healthcare system between October 2015 and June 2021. We compared frequencies of measured variables between each of the progesterone treated groups to no treatment using Pearson chi-squared tests and independent t-tests for categorical and continuous variables, respectively. We estimated crude and adjusted associations between each specific treatment (versus no treatment) and primary outcomes using logistic regression.

RESULTS

Recurrent sPTB < 37 weeks' gestation occurred in 22.3% (n = 64) of those in the no treatment group, 29.1% (n = 86, p = .077) in the 17-OHPC group, and 14.3% (n = 6, p = 0.325) in the vaginal progesterone group. Recurrent sPTB < 34 weeks' gestation was 6.6% (n = 19) in the no treatment group, 11.8% (n = 35, p = .043) in the 17-OHPC group, and 7.1% (n = 3, p = 1) in the vaginal progesterone group. Among all participants, neither 17-OHPC nor vaginal progesterone was significantly associated with a reduction in recurrent sPTB at any time point. Among those with a short cervix, IM 17-OHPC was positively associated with recurrent sPTB < 37 weeks' gestation (aOR 5.61; 95% CI 1.16, 42.9).

CONCLUSIONS

Progesterone therapy of any type did not reduce the risk of recurrent sPTB < 34 or < 37 weeks' gestation compared to no progesterone therapy.

Effectiveness of 17-OHP for Prevention of Recurrent Preterm Birth: A Retrospective Cohort Study

OBJECTIVE

17-α-hydroxyprogesterone caproate (17-OHP) has been recommended by professional societies for the prevention of recurrent preterm birth, but subsequent clinical studies have reported conflicting efficacy results. This study aimed to contribute to the evidence base regarding the effectiveness of 17-OHP in clinical practice using real-world data.

STUDY DESIGN

A total of 4,422 individuals meeting inclusion criteria representing recurrent spontaneous preterm birth (sPTB) were identified in a database of insurance claims, and 568 (12.8%) received 17-OHP. Crude and propensity score-matched recurrence rates and risk ratios (RRs) for the association of receiving 17-OHP on recurrent sPTB were calculated.

RESULTS

Raw sPTB recurrence rates were higher among those treated versus not treated; after propensity score matching, no association was detected (26.3 vs. 23.8%, RR = 1.1, 95% CI: 0.9-1.4).

CONCLUSION

We failed to identify a beneficial effect of 17-OHP for the prevention of spontaneous recurrent preterm birth in our observational, U.S. based cohort.

KEY POINTS

· We observed higher risk for sPTB in the group receiving 17-OHP in the unmatched analysis. · After propensity-score matching, we still failed to identify a beneficial effect of 17-OHP on sPTB. · Sensitivity analyses demonstrated robustness to the inclusion criteria and modeling assumptions..

Estimates of avoided costs attributed to a short cervix screening program to prevent preterm birth from the perspective of the Unified Health System (SUS)

OBJECTIVE

To perform an economic cost analysis of the implementation of a short cervix screening program to reduce preterm birth in singleton pregnancies in a short-term time horizon.

METHODS

We performed a cost-benefit economic analysis using the P5 trial database, a randomized multicenter clinical trial for prevention of preterm birth. Data collection was conducted from July 2015 to March 2019 in 17 different Brazilian hospitals. We conducted a cost analysis for universal cervical screening in singleton pregnancies between 18 weeks and 22 weeks plus 6 days. In subjects with a cervical length ≤ 25 mm, the analysis incorporated the costs of administering 200 mg/day of vaginal progesterone prophylactically until 36 weeks gestation. These findings were subsequently compared with the economic implications of forgoing cervical screening. The time horizon comprised from birth to 10 weeks postpartum. The outcome was measured monetarily in Brazilian real (R$) from the perspective of the Unified Health System.

RESULTS

Among 7,844 women, 6.67% (523) had a cervix ≤ 25 mm. The cost of screening with transvaginal ultrasound and vaginal progesterone for prevention of births with < 34 weeks was estimated at R$ 383,711.36, while non-screening generated an estimated additional cost of R$ 446,501.69 (related to the 29 non-screened preterm deliveries). Thus, screening and prophylaxis would generate a final cost reduction of R$ 62,790.33, constituting a possible cost-benefit strategy.

CONCLUSION

Universal short cervix screening for preterm birth has lower costs compared to non-screening within a short-term time horizon, which suggests an interesting benefit-cost ratio. Future studies should consider the cost-effectiveness of prophylactic treatment using sensitivity analyses in different scenarios within the Brazilian health system, as well as analyses that consider the long-term costs associated with preterm births, to robustly justify the implementation of a short cervix screening program.

Changes in use of 17-OHPC after the PROLONG trial: a physician survey

OBJECTIVES

To determine if 17α-hydroxyprogesterone caproate (17OHPC) or vaginal progesterone use for patients at risk for preterm birth has changed since the publication of the 17-OHPC to Prevent Recurrent Preterm Birth in Singleton Gestations (PROLONG) trial, and to assess which organizations' (Food and Drug Administration's [FDA], American College of Obstetrics and Gynecology's [ACOG] or Society of Maternal Fetal Medicine's [SMFM]) statements most influenced change.

METHODS

Through a vignette-based physician survey, we sought to measure (by Likert scale) how counseling tendencies regarding 17OHPC and vaginal progesterone have changed since the PROLONG trial publication. Participants were also asked which organizations' statements most influenced change.

RESULTS

With response rate of 97 % (141/145), a pre-to-post PROLONG trial comparison revealed significant changes in counseling for progesterone. Respondents were less likely to recommend 17OHPC (p<0.001) and more likely to recommend vaginal (p<0.001). The FDA statement most influenced the decision not to recommend 17OHPC for the prevention of preterm birth (r=-0.23, p=0.005).

CONCLUSIONS

Providers have made significant changes in their counseling regarding progesterone use for patients at risk for preterm birth after the publication of the PRLONG trial.

Reassessing Preterm Birth Prevention After the Withdrawal of 17-α Hydroxyprogesterone Caproate

The U.S. Food and Drug Administration has recently withdrawn approval for 17-α hydroxyprogesterone caproate for prevention of recurrent preterm birth, and recent studies have called into question benefits of the pessary in the setting of a short cervix. Obstetric health care professionals are once again left with limited remaining options for preterm birth prevention. This narrative review summarizes the best current evidence on the use of vaginal progesterone, low-dose aspirin, and cerclage for the prevention of preterm birth; attempts to distill possible lessons learned from studies of progesterone and pessary, as well as their implementation into practice; and highlights areas where inroads into preterm birth prevention may be possible outside of the progesterone-aspirin-cerclage paradigm.

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'.

Regional differences in utilization of 17α-hydroxyprogesterone caproate (17-OHP)

OBJECTIVES

To describe regional differences in utilization of 17α-hydroxyprogesterone caproate (17-OHP).

METHODS

Retrospective cohort study of a large, US commercial managed care plan claims database with pharmacy coverage from 2008 to 2018. Singleton pregnancies with at least one prior spontaneous preterm birth (sPTB) were included. Regional and state-based differences in 17-OHP use were compared. Data were analyzed using t-tests and Fisher's exact tests.

RESULTS

Of the 4,514 individuals with an indication for 17-OHP, 580 (12.8%) were prescribed 17-OHP. Regional and state-based differences in 17-OHP utilization were identified; Northeast 15.7%, Midwest 13.7%, South 12.0%, and West 10.4% (p=0.003).

CONCLUSIONS

While significant regional differences in 17-OHP utilization were demonstrated, 17-OHP utilization remained low despite this cohort having insurance through a US commercial managed care plan. Suboptimal utilization demonstrates a disconnect between research and uptake in clinical practice. This underscores a need for implementation science in obstetrics to translate updated recommendations more effectively and efficiently into clinical practice.

Association of Vaginal Progesterone Treatment With Prevention of Recurrent Preterm Birth

IMPORTANCE

Preterm birth (PTB) is the leading cause of infant morbidity and mortality worldwide. It has been suggested that vaginal progesterone (VP) treatment may reduce the recurrence of PTB.

OBJECTIVE

To evaluate the association of VP treatment with prevention of recurrent PTB among patients with a singleton pregnancy.

DESIGN, SETTING, AND PARTICIPANTS

This prospective, observational cohort study, set in a public health care system for inner-city pregnant patients, enrolled patients with prior spontaneous PTB (gestational age, ≤35 weeks) receiving VP from May 15, 2017, to May 7, 2019. Patients who delivered between 1998 and 2011 served as a referent cohort matched 3:1 for obesity, race and ethnicity, and individual specific preterm birth history. Statistical analysis was performed from August 19, 2021, to September 2, 2022.

EXPOSURE

Patients received 90 mg of vaginal progesterone, 8%, nightly, initiated between 16 weeks and 0 days and 20 weeks and 6 days of pregnancy until 36 weeks and 6 days of pregnancy or delivery.

MAIN OUTCOMES AND MEASURES

The primary outcome was overall rate of recurrent PTB at 35 weeks or less of patients given VP compared with the 3:1 matched untreated historical controls. Secondary outcomes included assessment of PTB according to adherence (≥80% completing scheduled doses), duration of pregnancy relative to index gestational age, progesterone blood levels, and outcomes for those who declined VP.

RESULTS

A total of 417 patients (mean [SD] age, 30.4 [5.9] years; 64 Black patients [15.3%]; 272 [65.2%] with a body mass index of ≥30) received VP and were matched with 1251 controls (mean [SD] age, 28.8 [5.7] years; 192 Black patients [15.3%]; 816 [65.2%] with a body mass index of ≥30). The overall rate of recurrent PTB was 24.0% (100 of 417; 95% CI, 20.0%-28.4%) for the VP cohort compared with 16.8% (1394 of 8278) expected in the matched historical controls. Adherence was not associated with lower rates of recurrent PTB compared with nonadherence (odds ratio, 0.87 [95% CI, 0.51-1.41]). The mean difference between historical matched controls and those using VP was 0.2 weeks (95% CI, -1.4 to 1.0 weeks) without improvement in the interval of recurrent PTB after the implementation of VP (P = .73). Progesterone blood levels for patients who were adherent compared with those who were nonadherent were not significantly different at either 24 or 32 weeks (24 weeks: 99 ng/mL [95% CI, 85-121 ng/mL] vs 104 ng/mL [95% CI, 89-125 ng/mL]; P = .16; 32 weeks: 200 ng/mL [95% CI, 171-242 ng/mL] vs 196 ng/mL [95% CI, 155-271 ng/mL]; P = .69).

CONCLUSIONS AND RELEVANCE

This cohort study of patients with a current singleton pregnancy suggests that VP was not associated with a reduction in recurrent PTB.

Genetics, epigenetics, and transcriptomics of preterm birth

Preterm birth contributes significantly to neonatal mortality and morbidity. Despite its global significance, there has only been limited progress in preventing preterm birth. Spontaneous preterm birth (sPTB) results from a wide variety of pathological processes. Although many non-genetic risk factors influence the timing of gestation and labor, compelling evidence supports the role of substantial genetic and epigenetic influences and their interactions with the environment contributing to sPTB. To investigate a common and complex disease such as sPTB, various approaches such as genome-wide association studies, whole-exome sequencing, transcriptomics, and integrative approaches combining these with other 'omics studies have been used. However, many of these studies were typically small or focused on a single ethnicity or geographic region with limited data, particularly in populations at high risk for sPTB, or lacked a robust replication. These studies found many genes involved in the inflammation and immunity-related pathways that may affect sPTB. Recent studies also suggest the role of epigenetic modifications of gene expression by the environmental signals as a potential contributor to the risk of sPTB. Future genetic studies of sPTB should continue to consider the contributions of both maternal and fetal genomes as well as their interaction with the environment.

Does vaginal progesterone prevent recurrent preterm birth in women with a singleton gestation and a history of spontaneous preterm birth? Evidence from a systematic review and meta-analysis

OBJECTIVE

To assess the efficacy and safety of vaginal progesterone to prevent recurrent preterm birth and adverse perinatal outcomes in singleton gestations with a history of spontaneous preterm birth.

DATA SOURCES

MEDLINE, Embase, LILACS, and CINAHL (from their inception to February 28, 2022), Cochrane databases, Google Scholar, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that compared vaginal progesterone to placebo or no treatment in asymptomatic women with a singleton gestation and a history of spontaneous preterm birth.

METHODS

The primary outcomes were preterm birth <37 and <34 weeks of gestation. The secondary outcomes included adverse maternal and perinatal outcomes. Pooled relative risks with 95% confidence intervals were calculated. We assessed the risk of bias in the included studies, heterogeneity (I2 test), small-study effects, publication bias, and quality of evidence; performed subgroup and sensitivity analyses; and calculated 95% prediction intervals and adjusted relative risks.

RESULTS

Ten studies (2958 women) met the inclusion criteria: 7 with a sample size <150 (small studies) and 3 with a sample size >600 (large studies). Among the 7 small studies, 4 were at high risk of bias, 2 were at some concerns of bias, and only 1 was at low risk of bias. All the large studies were at low risk of bias. Vaginal progesterone significantly decreased the risk of preterm birth <37 weeks (relative risk, 0.64; 95% confidence interval, 0.50-0.81; I2=75%; 95% prediction interval, 0.31-1.32; very low-quality evidence) and <34 weeks (relative risk, 0.62; 95% confidence interval, 0.42-0.92; I2=66%; 95% prediction interval, 0.23-1.68; very low-quality evidence), and the risk of admission to the neonatal intensive care unit (relative risk, 0.53; 95% confidence interval, 0.33-0.85; I2=67%; 95% prediction interval, 0.16-1.79; low-quality evidence). There were no significant differences between the vaginal progesterone and the placebo or no treatment groups in other adverse perinatal and maternal outcomes. Subgroup analyses revealed that vaginal progesterone decreased the risk of preterm birth <37 weeks (relative risk, 0.43; 95% confidence interval, 0.33-0.55; I2=0%) and <34 weeks (relative risk, 0.27; 95% confidence interval, 0.15-0.49; I2=0%) in the small but not in the large studies (relative risk, 0.98; 95% confidence interval, 0.88-1.09; I2=0% for preterm birth <37 weeks; and relative risk, 0.94; 95% confidence interval, 0.78-1.13; I2=0% for preterm birth <34 weeks). Sensitivity analyses restricted to studies at low risk of bias indicated that vaginal progesterone did not reduce the risk of preterm birth <37 weeks (relative risk, 0.96; 95% confidence interval, 0.84-1.09) and <34 weeks (relative risk, 0.90; 95% confidence interval, 0.71-1.15). There was clear evidence of substantial small-study effects in the meta-analyses of preterm birth <37 and <34 weeks of gestation because of funnel plot asymmetry and the marked differences in the pooled relative risks obtained from fixed-effect and random-effects models. The adjustment for small-study effects resulted in a markedly reduced and nonsignificant effect of vaginal progesterone on preterm birth <37 weeks (relative risk, 0.86; 95% confidence interval, 0.68-1.10) and <34 weeks (relative risk, 0.92; 95% confidence interval, 0.60-1.42).

CONCLUSION

There is no convincing evidence supporting the use of vaginal progesterone to prevent recurrent preterm birth or to improve perinatal outcomes in singleton gestations with a history of spontaneous preterm birth.

17-α Hydroxyprogesterone Caproate Immunology, a Special Focus on Preterm Labor, Preeclampsia, and COVID-19

17-α hydroxyprogesterone caproate (17-OHPC) could alter the immune response and inflammation, specifically affecting the risk of preterm labor and preeclampsia. However, the exact immune and inflammatory effects of 17-OHPC remain hard to be identified. The current literature on 17-OHPC immune effects is limited and more research is needed to identify these mechanistic pathways. Further, coronavirus disease 2019 (COVID-19) infection in pregnancy involves heightened immune response, widespread inflammation and high rates of preterm labor and preeclampsia. Since the pathogenesis of preterm labor, preeclampsia and COVID-19 involves inflammation and altered immune response, it is important to explore the possible immune effects of 17-OHPC in pregnant women with COVID-19. This commentary article will explain the immune effects of 17-OHPC and their implications in preterm labor, preeclampsia and COVID-19.

Vaginal progesterone vs intramuscular 17-hydroxyprogesterone caproate for prevention of recurrent preterm birth: a randomized controlled trial

BACKGROUND

Preterm birth is the leading cause of neonatal morbidity and mortality, and previous preterm birth is one of the strongest risk factors for preterm birth. National and international obstetrical societies have different recommendations regarding progesterone formulation for the prevention of recurrent preterm birth.

OBJECTIVE

This study aimed to determine whether vaginal progesterone is superior to 17-hydroxyprogesterone caproate in the prevention of recurrent preterm birth in patients with singleton pregnancies who had a previous spontaneous preterm birth.

STUDY DESIGN

This was an open-label multicenter pragmatic randomized controlled trial at 5 US centers of patients with singleton pregnancies at <24 weeks of gestation who had a previous spontaneous preterm birth randomized 1:1 to either 200 mg vaginal progesterone suppository nightly or 250 mg intramuscular 17-hydroxyprogesterone caproate weekly from 16 to 36 weeks of gestation. Based on the estimated recurrent preterm birth rate of 36% with 17-hydroxyprogesterone caproate, 95 participants were needed in each arm to detect a 50% reduction in preterm birth rate with vaginal progesterone, with 80% power and 2-sided alpha of 0.05. The primary outcome was preterm birth at <37 weeks of gestation. Prespecified secondary outcomes included preterm birth at <34 and <28 weeks of gestation, mean gestational age at delivery, neonatal morbidity and mortality, and measures of adherence. Analysis was by intention to treat. The chi-square test and Student t test were used as appropriate. P<.05 was considered significant.

RESULTS

Overall, 205 participants were randomized; 94 participants in the vaginal progesterone group and 94 participants in 17-hydroxyprogesterone caproate group were included. Although gestational age at enrollment was similar, those assigned to vaginal progesterone initiated therapy earlier (16.9±1.4 vs 17.8±2.5 weeks; P=.001). Overall continuation of assigned formulation until delivery was similar (73% vs 69%; P=.61). There was no significant difference in preterm birth at <37 (31% vs 38%; P=.28; relative risk, 0.81 [95% confidence interval, 0.54-1.20]), <34 (9.6% vs 14.9%; P=.26; relative risk, 0.64 [95% confidence interval, 0.29-1.41]), or <28 (1.1% vs 4.3%; P=.37; relative risk, 0.25 [95% confidence interval, 0.03-2.20]) weeks of gestation. Participants in the vaginal progesterone group had a later mean gestational age at delivery than participants in the 17-hydroxyprogesterone caproate group (37.36±2.72 vs 36.34±4.10 weeks; mean difference, 1.02 [95% confidence interval, 0.01-2.01]; P=.047).

CONCLUSION

Vaginal progesterone did not reduce the risk of recurrent preterm birth by 50% compared with 17-OHPC; however, vaginal progesterone may lead to increased latency to delivery. This trial was underpowered to detect a smaller, but still clinically significant, difference in the efficacy of preterm birth prevention. Patient factors that impact adherence and ability to obtain medication in a timely fashion should be included in counseling on progesterone selection.

Perinatal care for the extremely preterm infant

Being born preterm (prior to 37 weeks of completed gestation) is a leading cause of childhood death up to five years of age, and is responsible for the demise of around one million preterm infants each year. Rates of prematurity, which range from approximately 5 to 18% of births, are increasing in most countries. Babies born extremely preterm (less than 28 weeks' gestation) and in particular, in the periviable (20^0/7-25^6/7 weeks) period, are at the highest risk of death, or the development of long-term disabilities. The perinatal care of extremely preterm infants and their mothers raises a number of clinical, technical, and ethical challenges. Focusing on 'micropremmies', or those born in the periviable period, this paper provides an update regarding the aetiology and impacts of periviable preterm birth, advances in the antenatal, intrapartum, and acute post-natal management of these infants, and a review of counselling/support approaches for engaging with the infant's family. It concludes with an overview of emerging technology that may assist in improving outcomes for this at-risk population.

Use of cervical elastography at 18 to 22 weeks' gestation in the prediction of spontaneous preterm birth

BACKGROUND

Accurate identification of the women who will have spontaneous preterm birth continues to be a great challenge. The use of cervical elastography for prediction of preterm birth is promising, but several limitations exist. Newer cervical elastography technology has been developed that may prove useful in evaluation of risk of preterm birth.

OBJECTIVE

This study aimed to develop standard cervical elastography nomograms for singleton pregnancies at 18 to 22 weeks' gestation using the E-Cervix ultrasound application, assess intraobserver reliability of the E-Cervix elastography parameters, and determine whether these cervical elastography measurements can be used in the prediction of spontaneous preterm birth.

STUDY DESIGN

This was a prospective cohort study of pregnant women undergoing cervical length screening assessment via transvaginal ultrasound examination at 18 to 22 weeks' gestation. A semiautomatic, cervical elastography application (E-Cervix) was used during the transvaginal examination to calculate 5 quantitative parameters (internal os stiffness, external os stiffness, internal -to -external os stiffness ratio, hardness ratio, and elasticity contrast index) and create a standard nomogram for each one of them. The intraobserver reliability was calculated using Shrout-Fleiss reliability. Cervical elastography parameters were compared between those who delivered preterm (<37 weeks) spontaneously and those who delivered full term. A multivariable logistic regression model was performed to determine the ability of the cervical elastography parameters to predict spontaneous preterm birth.

RESULTS

A total of 742 women were included, of which 49 (6.6%) had a spontaneous preterm delivery. A standard nomogram was created for each of the cervical elastography parameters from those who had a full-term birth in the index pregnancy (n=693). Intraobserver reliability was good or excellent (intraclass correlation, 0.757-0.887) for each of the cervical elastography parameters except external os stiffness which was poor (intraclass correlation, 0.441). In univariate analysis, none of the cervical elastography parameters were associated with a statistically significant increased risk of spontaneous preterm birth. In a multivariable model adjusting for history of preterm birth, gravidity, ethnicity, cervical cerclage, and vaginal progesterone use, increasing elasticity contrast index was significantly associated with an increased risk of spontaneous preterm birth (odds ratio, 1.15; 95% confidence interval, 1.02-1.30; P=.02).

CONCLUSION

Cervical elastography parameters are reliably measured and are stable across 18 to 22 weeks' gestation. Based on our findings, the elasticity contrast index was associated with an increased risk of spontaneous preterm birth and may be a useful parameter for future research.

Weekly 17 alpha-hydroxyprogesterone caproate to prevent preterm birth among women living with HIV: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Women with HIV face an increased risk of preterm birth. 17 alpha-hydroxyprogesterone caproate (17P) has been shown in some trials to reduce early delivery among women with a history of spontaneous preterm birth. We investigated whether 17P would reduce this risk among women with HIV.

METHODS

We did a randomised, double-blind, placebo-controlled trial in pregnant women with HIV at the University Teaching Hospital and Kamwala District Health Centre in Lusaka, Zambia. Eligible patients were women aged 18 years or older with confirmed HIV-1 infection, viable intrauterine singleton pregnancy at less than 24 weeks of gestation, and were receiving or intending to commence antiretroviral therapy during pregnancy. Exclusion criteria were major uterine or fetal anomaly; planned or in situ cervical cerclage; evidence of threatened miscarriage, preterm labour, or ruptured membranes at screening; medical contraindication to 17P; previous participation in the trial; or history of spontaneous preterm birth. Eligible participants provided written informed consent and were randomly assigned (1:1) to receive 250 mg intramuscular 17P or placebo once per week, starting between 16 and 24 weeks of gestation until delivery, stillbirth, or reaching term (37 weeks). Participants and study staff were masked to assignment, except for pharmacy staff who did random assignment and prepared injections but did not interact with participants. The primary outcome was a composite of delivery before 37 weeks or stillbirth at any gestational age. Patients attended weekly visits for study drug injections and antenatal care. We estimated the absolute and relative difference in risk of the primary outcome and safety events between treatment groups by intention to treat. This trial is registered with ClinicalTrials.gov, NCT03297216, and is complete.

FINDINGS

Between Feb 7, 2018 and Jan 13, 2020, we assessed 1042 women for inclusion into the study. 242 women were excluded after additional assessments, and 800 eligible patients were enrolled and randomly assigned to receive intramuscular 17P (n=399) or placebo (n=401). Baseline characteristics were similar between groups. Adherence to study drug injections was 98% in both groups, no patients were lost to follow-up, and the final post-partum visit was on Aug 6, 2020. 36 (9%) of 399 participants assigned to 17P had preterm birth or stillbirth, compared with 36 (9%) of 401 patients assigned to placebo (risk difference 0·1, 95% CI -3·9 to 4·0; relative risk 1·0, 95% CI 0·6 to 1·6; p=0·98). Intervention-related adverse events were reported by 140 (18%) of 800 participants and occurred in similar proportions in both randomisation groups. No serious adverse events were reported.

INTERPRETATION

Although 17P seems to be safe and acceptable to participants, available data do not support the use of the drug to prevent preterm birth among women whose risk derives solely from HIV infection. The low risk of preterm birth in both randomisation groups warrants further investigation.

FUNDING

US National Institutes of Health and the Bill and Melinda Gates Foundation.

Prevention of Preterm Birth with Progesterone

Gestational age at birth is a critical factor for perinatal and adulthood outcomes, and even for transgenerational conditions' effects. Preterm birth (PTB) (prematurity) is still the main determinant for infant mortality and morbidity leading cause of infant morbidity and mortality. Unfortunately, preterm birth (PTB) is a relevant public health issue worldwide and the global PTB rate is around 11%. The premature activation of labor is underlined by complex mechanisms, with a multifactorial origin influenced by numerous known and probably unknown triggers. The possible mechanisms involved in a too early labor activation have been partially explained, and involve chemokines, receptors, and imbalanced inflammatory paths. Strategies for the early detection and prevention of this obstetric condition were proposed in clinical settings with interesting results. Progesterone has been demonstrated to have a key role in PTB prevention, showing several positive effects, such as lower prostaglandin synthesis, the inhibition of cervical stromal degradation, modulating the inflammatory response, reducing gap junction formation, and decreasing myometrial activation. The available scientific knowledge, data and recommendations address multiple current areas of debate regarding the use of progesterone in multifetal gestation, including different formulations, doses and routes of administration and its safety profile in pregnancy.

Developmental exposure to the synthetic progestin, 17α-hydroxyprogesterone caproate, disrupts the mesocortical serotonin pathway and alters impulsive decision-making in rats

The synthetic progestin, 17α-hydroxyprogesterone caproate (17-OHPC), is administered to women at risk for preterm birth during a critical period of fetal development for mesocortical pathways. Yet, little information is available regarding the potential effects of 17-OHPC on the developing fetal brain. In rat models, the mesocortical serotonin pathway is sensitive to progestins. Progesterone receptor (PR) is expressed in layer 3 pyramidal neurons of medial prefrontal cortex (mPFC) and in serotonergic neurons of the dorsal raphe. The present study tested the hypothesis that exposure to 17-OHPC during development disrupts serotonergic innervation of the mPFC in adolescence and impairs behavior mediated by this pathway in adulthood. Administration of 17-OHPC from postnatal days 1-14 decreased the density of SERT-ir fibers within superficial and deep layers and decreased the density of synaptophysin-ir boutons in all layers of prelimbic mPFC at postnatal day 28. In addition, rats exposed to 17-OHPC during development were less likely to make impulsive choices in the Delay Discounting task, choosing the larger, delayed reward more often than controls at moderate delay times. Interestingly, 17-OHPC exposed rats were more likely to fail to make any choice (i.e., increased omissions) compared to controls at longer delays, suggesting disruptions in decision-making. These results suggest that further investigation is warranted in the clinical use of 17-OHPC to better inform a risk/benefit analysis of progestin use in pregnancy.

Utilization, adherence, and outcomes of 17-alpha hydroxyprogesterone caproate for recurrent spontaneous preterm birth prevention

OBJECTIVE

To describe the use of and adherence to 17-alpha hydroxyprogesterone caproate (17-OHPC), explore factors associated with its utilization and adherence, and to investigate the outcomes of 17-OHPC in a real-world setting.

METHODS

The Decision Resources Group (DRG) database (1 January 2012-31 December 2017) was used to identify women with diagnosis of "history of preterm labor", aged 16-50 years old, had a singleton gestation, were continuously enrolled for at least 6 months and 9 months before and after the index date, respectively, and had a delivery outcome recorded. Adequate adherence was defined and compared using two approaches: (1) patients receiving at least 10 injections of 17-OHPC; (2) number of received injections/eligible number of injections ≥0.7. The outcome of 17-OHPC was evaluated by the incidence rate of preterm birth (PTB). Bivariate tests compared patients' characteristics with their use of and adherence to 17-OHPC, and examined the associations between 17-OHPC utilization and incidence of diabetes or hypertension. Stepwise logistic regression was conducted to assess the effect of adherence on the delivery outcome.

RESULTS

Of 28,339 patients meeting study criteria, 2585 (9.1%) had ≥1 claim for 17-OHPC. An increasing trend of utilization was observed from 2012 to 2017 (7.6-13.1%). The utilization rate was highest in the Southwest US (13.8%) (p < .001). Commercial insurance patients (9.6%) were more likely to use 17-OHPC than Medicaid patients (7.9%) (p < .001). Patients with higher Charlson Comorbidity Index (CCI) scores were less likely to use 17-OHPC. Of women prescribed 17-OHPC, 792 (30.6%) and 424 (16.4%) were adherent using two definitions, respectively. No difference in PTB rate was observed between adherers and non-adherers (definition 1: aOR = 0.97, 95% CI = 0.81-1.16; definition 2: aOR = 1.18, 95% CI = 0.95-1.48). No association was found between 17-OHPC and incidence of diabetes (p = .96); however, use of 17-OHPC was associated with a lower incidence rate of hypertension (p = .002).

CONCLUSIONS

17-OHPC utilization and adherence rates remain low. Insurance type and geographic region were associated with both utilization and adherence. There was no association between 17-OHPC adherence and effectiveness. More evidence is needed to determine if the use of 17-OHPC is advantageous in a sub-group of patients.

A chronicle of the 17-alpha hydroxyprogesterone caproate story to prevent recurrent preterm birth

Preterm birth is a substantial public health concern. In 2019, the US preterm birth rate was 10.23%, which is the fifth straight year of increase in this rate. Moreover, preterm birth accounts for approximately 1 in 6 infant deaths, and surviving children often suffer developmental delay or long-term neurologic impairment. Although the burden of preterm birth is clear, identifying strategies to reduce preterm birth has been challenging. On October 29, 2019, a US Food and Drug Administration advisory committee voted 9 vs 7 to withdraw interim accelerated approval of 17-alpha hydroxyprogesterone caproate for preventing recurrent preterm birth because the called for a confirmatory trial, known as the Prevention of Preterm Birth in Women With a Previous Singleton Spontaneous Preterm Delivery trial, was not confirmatory. The Prevention of Preterm Birth in Women With a Previous Singleton Spontaneous Preterm Delivery trial included subjects enrolled in the United States and Canada to ensure that at least 10% of patients would be from North America; however, this trial took 9 years to complete and did not demonstrate significant treatment effects in the 2 primary outcomes of interest. Delivery before 35 weeks' gestation occurred in 122 of 1130 women (11%) given 17-alpha hydroxyprogesterone caproate compared with 66 of 578 women (11.5%) given placebo (relative risk, 0.95; 95% confidence interval, 0.71-1.26; P=.72). Similarly, the coprimary outcome neonatal composite index occurred in 61 of 1093 women (5.6%) given 17-alpha hydroxyprogesterone caproate compared with 28 of 559 women (5.0%) given placebo (relative risk, 1.12; 95% confidence interval, 0.68-1.61; P=.73). There was also a lack of efficacy for 17-alpha hydroxyprogesterone caproate treatment in the analysis of a variety of secondary outcomes. Like the Maternal-Fetal Medicine Units Network trial, the Prevention of Preterm Birth in Women With a Previous Singleton Spontaneous Preterm Delivery trial was also flawed. Importantly, the Maternal-Fetal Medicine Unit Network trial was the sole justification for treating women in the United States with 17-alpha hydroxyprogesterone caproate for nearly 2 decades. Currently, despite more than half a century, 17-alpha hydroxyprogesterone caproate still has not been found to be clearly effective. In this context, how does the advising physician dependent on scientific evidence advise a patient that 17-alpha hydroxyprogesterone caproate is effective when the evidence to support this advice has repeatedly been found to be inadequate? This clinical opinion is a critical appraisal of the 2 randomized trials examining the efficacy of 17-alpha hydroxyprogesterone caproate to prevent recurrent preterm birth and a chronicle of events in the regulatory process of drug approval to help answer this question. With this examination, these events illustrate the complexity of pharmaceutical regulations in the era of accelerated Food and Drug Administration approval and characterize the financial impact and influence in medicine. In this report, we also emphasize the value of observational studies in contemporary practice and identify other examples in medicine where accelerated Food and Drug Administration approval has been withdrawn. Importantly, the themes of the 17-alpha hydroxyprogesterone caproate story are not limited to obstetrics. It can also serve as a microcosm of issues within the US healthcare system, which ultimately contributes to the high cost of healthcare. In our opinion, the answer to the question is clear-the facts speak for themselves-and we believe 17-alpha hydroxyprogesterone caproate should not be endorsed for use to prevent recurrent preterm birth in the United States.

17-Hydroxyprogesterone Caproate for the Prevention of Recurrent Preterm Birth - A Systematic Review and Meta-analysis Taking into Account the PROLONG Trial

Background Prior spontaneous preterm birth is a strong risk factor for the recurrence of spontaneous preterm birth in a subsequent pregnancy and has been evaluated in prevention studies using progesterone (natural progesterone administered orally or vaginally, and 17-hydroxyprogesterone caproate [17-OHPC]) as a selection criterion. Based on the findings of a randomized, placebo-controlled study, 17-OHPC was approved for use in 2011 by the Food and Drug Administration in the USA for the prevention of recurrent preterm birth. The approval was granted with qualification that a subsequent confirmatory study would need to be carried out, the results of which have just been published (PROLONG trial). Method A systematic literature search for the period from 1970 to April 2020 using the search terms "preterm birth" and "17-OHPC" or "progesterone" was carried out. Only randomized, placebo-controlled studies of women with singleton pregnancies who received 17-OHPC to prevent recurrent preterm birth were included in the subsequent meta-analysis. The relative risk and associated 95% confidence intervals were calculated. The heterogeneity between studies was evaluated with I ² statistics. Results In addition to the original study used for the approval and the PROLONG trial, only one other study was found which met the inclusion criteria (total number of patients: 2221). With considerable heterogeneity between the studies, particularly with respect to the risk factors for preterm birth, the comparison between 17-OHPC and placebo showed no significant reduction in preterm birth rates before 37, 35 and 32 weeks of gestation and no significant differences with regard to the prevalence of miscarriage before 20 weeks of gestation or fetal deaths (antepartum or intrapartum) after 20 weeks of gestation and neonatal morbidity. Conclusion Based on the currently available data, 17-OHPC cannot be recommended for the prevention of recurrent preterm birth. Further randomized, placebo-controlled studies with clearly defined, comparable risk factors are required to identify the group of pregnant women which could benefit from the use of 17-OHPC to prevent preterm birth.

Current Approaches to Risk Assessment and Prevention of Preterm Birth-A Continuing Public Health Crisis

Background: Preterm birth remains a major cause of neonatal morbidity and mortality. Several potential pathways and pathophysiologic processes can lead to preterm birth, complicating efforts to screen for the risk of preterm birth and making implementation of prevention strategies difficult.

Methods: Based on a review of the literature, this article addresses screening strategies for preterm birth risk stratification and interventions for preterm birth prevention.

Results: In women with a history of a prior spontaneous preterm birth, cervical cerclage placement in the setting of short cervix reduces the rate of recurrent spontaneous preterm birth. Weekly injections of 17-hydroxyprogesterone caproate (17-P) have been used as standard treatment for the prevention of recurrent preterm birth since 2011. However, results of a replication study of 17-P published in 2020 have raised questions regarding the effectiveness of this drug, and it is under review by the US Food and Drug Administration. Among women with no history of preterm birth, cervical length appears to be the best predictor of risk for preterm birth in asymptomatic women. In women with a cervical length <25 mm, vaginal progesterone has been demonstrated to reduce the risk of preterm birth.

Conclusion: Strategies including cervical length screening, vaginal progesterone administration, cervical cerclage placement, and, potentially, 17-P administration may help reduce rates of preterm birth when used in the appropriate patient populations. Development of protocols for patient evaluation and risk stratification will help identify patients at highest risk for preterm birth and allow use of the best available therapeutic interventions.

Current Preterm Birth Prevention Strategies

Preterm birth remains a major issue in obstetrics. Despite efforts to reduce the incidence of preterm delivery, rates in the United States remain high at 10.2% of all live births with an incidence of 10.8% globally. Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. It is also the leading cause of death in children younger than 5 years. Research into this important health topic has allowed for the identification of risk factors for preterm birth, the most important of which is a history of prior preterm birth. Cervical length screening may allow us to identify those at greatest risk of recurrent preterm birth as well as a de novo risk in women with no prior preterm birth history.