Predictors of response to 17-alpha hydroxyprogesterone caproate for prevention of recurrent spontaneous preterm birth

Placental histology for targeted risk assessment of recurrent spontaneous preterm birth

BACKGROUND

Spontaneous preterm birth significantly increases the risk for a recurrent preterm birth. Only a few identifiable clinical risk factors can be referenced in counseling for recurrent preterm birth. Furthermore, treatment using progesterone supplementation has not consistently prevented preterm birth among high-risk patients, but it may be effective in a subset of those patients. Placental pathology from a previous pregnancy may be used to predict which patients will experience a recurrent preterm birth or to identify a subset of patients more likely to respond to treatment with antenatal progesterone.

OBJECTIVE

This study aimed to determine if histologic patterns are associated with recurrent preterm birth among patients with an index spontaneous preterm birth. A secondary objective was to determine if placental histologic types and/or progesterone receptor density in the decidua are associated with the response to progesterone supplementation with intramuscular 17-hydroxyprogesterone caproate.

STUDY DESIGN

This was a retrospective cohort study at a single institution of women with singleton pregnancies with an index spontaneous preterm birth and a subsequent birth within the same hospital system between 2009 and 2019. Patients were included if placental pathology was available for the index spontaneous preterm birth. A logistic regression was used to determine if there were independent associations between 4 histologic types (acute inflammation, maternal vascular malperfusion, fetal vascular malperfusion, chronic inflammation) and recurrent preterm birth. For the secondary endpoint, 17-hydroxyprogesterone caproate response was defined as prolonging gestation by >3 weeks beyond the gestational age at delivery in the index pregnancy. Patients who delivered <3 weeks beyond the gestational age in the index pregnancy but at ≥39 weeks' gestation were excluded. A logistic regression was used to assess the independent association between placental histology and 17-hydroxyprogesterone caproate response. Sensitivity analyses were completed using only patients with an index birth <36 weeks' gestation, and then excluding those with medically indicated preterm birth in a subsequent pregnancy. A nested case-control immunohistochemical study was done among 20 patients with a subsequent term birth and 20 patients with a subsequent spontaneous preterm birth. The percentage of cells in the maternal decidua positive for progesterone receptors was correlated with the subsequent pregnancy outcome.

RESULTS

A total of 352 patients were included. Acute inflammation was the most common histologic type seen among patients with spontaneous preterm birth (44.1%), followed by chronic inflammation (40.9%) and maternal vascular malperfusion (31.3%). No histologic type was independently associated with recurrent preterm birth. A total of 155 patients received 17-hydroxyprogesterone caproate in a second pregnancy. Low-grade acute inflammation was significantly associated with a decreased likelihood of 17-hydroxyprogesterone caproate response. Low-grade maternal vascular malperfusion among those with an index pregnancy delivered at <36 weeks' gestation was significantly associated with a more than 4 times increased likelihood of 17-hydroxyprogesterone caproate response when excluding those with a subsequent iatrogenic preterm birth. Progesterone receptor staining was not associated with recurrent preterm birth.

CONCLUSION

Although acute inflammation was prevalent among spontaneous preterm births, more than half of the spontaneous preterm births were not associated with acute inflammation. Low-grade acute inflammation was associated with a significantly decreased response to 17-hydroxyprogesterone caproate supplementation. Low-grade maternal vascular malperfusion was associated with a 4-fold increased likelihood of 17-hydroxyprogesterone caproate response among those with index deliveries <36 weeks' gestation. Further work is needed to determine if placental pathologic examination can be used to target treatment in subsequent pregnancies to prevent recurrent preterm birth.

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..

What now? A critical evaluation of over 20 years of clinical and research experience with 17-alpha hydroxyprogesterone caproate for recurrent preterm birth prevention

Spontaneous preterm birth is multifactorial, and underlying etiologies remain incompletely understood. Supplementation with progestogens, including 17-alpha hydroxyprogesterone caproate has been a mainstay of prematurity prevention strategies in the United States in the last 2 decades. Following a recent negative confirmatory trial, 17-alpha hydroxyprogesterone caproate was withdrawn from the US market and is currently available only through clinical research studies. This expert review summarized clinical and research data regarding the use of 17-alpha hydroxyprogesterone caproate in the United States from 2003 to 2023 for recurrent prematurity prevention. In 17-alpha hydroxyprogesterone caproate. The history of the use, mechanisms of action, clinical trial results, and efficacy by clinical and biologic criteria of 17-alpha hydroxyprogesterone caproate are presented. We report that disparate findings and conclusions between similarly designed rigorous studies may reflect differences in a priori risk and population incidence and extreme care should be taken in interpreting the studies and making decisions regarding efficacy of 17-alpha hydroxyprogesterone caproate for the prevention of preterm birth. The likelihood of improved obstetrical outcomes after receiving 17-alpha hydroxyprogesterone caproate may vary by clinical factors (eg, body mass index), plasma drug concentrations, and genetic factors, although the identification of individuals most likely to benefit remains imperfect. It is crucial for the medical community to recognize the importance of preserving the decades-long efforts invested in preventing recurrent preterm birth in the United States. Moreover, it is important that we thoroughly and thoughtfully evaluate 17-alpha hydroxyprogesterone caproate as a promising contender for future well-executed prematurity studies.

Cervical stitch (cerclage) in combination with other treatments for preventing spontaneous preterm birth in singleton pregnancies

BACKGROUND

Preterm birth (PTB) remains the foremost global cause of perinatal morbidity and mortality. Thus, the prevention of spontaneous PTB still remains of critical importance. In an attempt to prevent PTB in singleton pregnancies, cervical cerclage, in combination with other treatments, has been advocated. This is because, cervical cerclage is an intervention that is commonly recommended in women with a short cervix at high risk of preterm birth but, despite this, many women still deliver prematurely, as the biological mechanism is incompletely understood. Additionally, previous Cochrane Reviews have been published on the effectiveness of cervical cerclage in singleton and multiple pregnancies, however, none has evaluated the effectiveness of using cervical cerclage in combination with other treatments.

OBJECTIVES

To assess whether antibiotics administration, vaginal pessary, reinforcing or second cerclage placement, tocolytic, progesterone, or other interventions at the time of cervical cerclage placement prolong singleton gestation in women at high risk of pregnancy loss based on prior history and/or ultrasound finding of 'short cervix' and/or physical examination. History-indicated cerclage is defined as a cerclage placed usually between 12 and 15 weeks gestation based solely on poor prior obstetrical history, e.g. multiple second trimester losses due to painless dilatation. Ultrasound-indicated cerclage is defined as a cerclage placed usually between 16 and 23 weeks gestation for transvaginal ultrasound cervical length < 20 mm in a woman without cervical dilatation. Physical exam-indicated cerclage is defined as a cerclage placed usually between 16 and 23 weeks gestation because of cervical dilatation of one or more centimetres detected on physical (manual) examination.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (26 September 2019), and reference lists of retrieved studies.

SELECTION CRITERIA

We included published, unpublished or ongoing randomised controlled trial (RCTs). Studies using a cluster-RCT design were also eligible for inclusion in this review but none were identified. We excluded quasi-RCTs (e.g. those randomised by date of birth or hospital number) and studies using a cross-over design. We also excluded studies that specified addition of the combination therapy after cervical cerclage because the woman subsequently became symptomatic. We included studies comparing cervical cerclage in combination with one, two or more interventions with cervical cerclage alone in singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts of all retrieved articles, selected studies for inclusion, extracted data, assessed risk of bias, and evaluated the certainty of the evidence for this review's main outcomes. Data were checked for accuracy. Standard Cochrane review methods were used throughout.

MAIN RESULTS

We identified two studies (involving a total of 73 women) comparing cervical cerclage alone to a different comparator. We also identified three ongoing studies (one investigating vaginal progesterone after cerclage, and two investigating cerclage plus pessary). One study (20 women), conducted in the UK, comparing cervical cerclage in combination with a tocolytic (salbutamol) with cervical cerclage alone in women with singleton pregnancy did not provide any useable data for this review. The other study (involving 53 women, with data from 50 women) took place in the USA and compared cervical cerclage in combination with a tocolytic (indomethacin) and antibiotics (cefazolin or clindamycin) versus cervical cerclage alone - this study did provide useable data for this review (and the study authors also provided additional data on request) but meta-analyses were not possible. This study was generally at a low risk of bias, apart from issues relating to blinding. We downgraded the certainty of evidence for serious risk of bias and imprecision (few participants, few events and wide 95% confidence intervals). Cervical cerclage in combination with an antibiotic and tocolytic versus cervical cerclage alone (one study, 50 women/babies) We are unclear about the effect of cervical cerclage in combination with antibiotics and a tocolytic compared with cervical cerclage alone on the risk of serious neonatal morbidity (RR 0.62, 95% CI 0.31 to 1.24; very low-certainty evidence); perinatal loss (data for miscarriage and stillbirth only - data not available for neonatal death) (RR 0.46, 95% CI 0.13 to 1.64; very low-certainty evidence) or preterm birth < 34 completed weeks of pregnancy (RR 0.78, 95% CI 0.44 to 1.40; very low-certainty evidence). There were no stillbirths (intrauterine death at 24 or more weeks). The trial authors did not report on the numbers of babies discharged home healthy (without obvious pathology) or on the risk of neonatal death.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to evaluate the effect of combining a tocolytic (indomethacin) and antibiotics (cefazolin/clindamycin) with cervical cerclage compared with cervical cerclage alone for preventing spontaneous PTB in women with singleton pregnancies. Future studies should recruit sufficient numbers of women to provide meaningful results and should measure neonatal death and numbers of babies discharged home healthy, as well as other important outcomes listed in this review. We did not identify any studies looking at other treatments in combination with cervical cerclage. Future research needs to focus on the role of other interventions such as vaginal support pessary, reinforcing or second cervical cerclage placement, 17-alpha-hydroxyprogesterone caproate or dydrogesterone or vaginal micronised progesterone, omega-3 long chain polyunsaturated fatty acid supplementation and bed rest.

Racial Disparities in Prematurity Persist among Women of High Socioeconomic Status

Objectives

Despite persistent racial disparities in preterm birth (PTB) in the US among non-Hispanic (NH) black women compared to NH white women, it remains controversial whether sociodemographic factors can explain these differences. We sought to evaluate whether disparities in PTB persist among NH black women with high socioeconomic status (SES).

Study Design

We conducted a population-based cohort study of all live births in the US from 2015-2017 using birth certificate data from the National Vital Statistics System. We included singleton, non-anomalous live births among women who were of high SES (defined as having ≥ 16 years of education, private insurance, and not receiving Women, Infants and Children [WIC] benefits) and who identified as NH white, NH black, or 'mixed' NH black and white race. The primary outcome was PTB <37 weeks; secondary outcomes included PTB <34 and <28 weeks. In addition, analyses were repeated considering birthweight <2500g as a surrogate for preterm birth <37 weeks, birthweight <1500g as a surrogate for preterm birth <34 weeks, and birthweight <750g as a surrogate for preterm birth <28 weeks' gestation. Data were analyzed with chi-square, t-test, and logistic regression.

Results

2,170,686 live births met inclusion criteria, with 92.9% NH white, 6.7% NH black, and 0.4% both NH white and black race. Overall, 5.9% delivered <37, 1.3% <34, and 0.3 % <28 weeks. In unadjusted analyses of women with high SES, the PTB rate at each gestational age cutoff was higher for women of 'mixed' NH white and black race, and highest for women who were NH black only compared to women who were NH white only. In regression models we further adjusted for women with insurance and prenatal care their entire pregnancy, maternal race was associated with higher odds of PTB at each GA cutoff, with the highest odds observed at <28 weeks. Finally, in further adjustement analysis including only the 1,934,912 women who received prenatal care in the first trimester, findings were similar. Rates of preterm birth at each gestational age cutoff remained highest for women who identified as non-Hispanic black, intermediate for women identifying as both non-Hispanic black and white race, and lowest for non-Hispanic white women at <37 weeks (9.9% vs. 6.1% vs. 5.5%, respectively; p<0.001), <34 weeks (3.5% vs. 1.5% vs. 1.1%, respectively; p<0.001), and <28 weeks' gestation (1.2% vs. 0.4% vs. 0.2%, respectively, p<0.001).

Conclusions

Even among college-educated women with private insurance who are not receiving WIC, racial disparities in prematurity persist. These national findings are consistent with prior studies that suggest factors other than socio-demographics are important in the underlying pathogenesis of PTB.

Pharmacology for Preterm Labor

Preterm birth occurs with 10% of deliveries and yet accounts for more than 85% of perinatal morbidity and mortality. Management of preterm labor prior to delivery includes a multipronged pharmacologic approach targeting utilization of reproductive hormones for continuation of pregnancy, advancement of fetal lung maturity, and the decrease of uterine contractility (tocolysis). This article will review and compare guidelines on pharmacologic management of preterm labor as recommended by the American College of Obstetricians and Gynecologists and the European Association of Perinatal Medicine. The classifications of drugs discussed include exogenous progesterone, corticosteroids, and tocolytics (β-adrenergic agonists, magnesium sulfate, calcium channel blockers, prostaglandin inhibitors, nitrates, and oxytocin receptor blockers). For each of these drug classes, the following information will be presented: mechanism of action, maternal/fetal side effects, and nursing implications.

Epigenetic Regulation of the Nitric Oxide Pathway, 17-α Hydroxyprogesterone Caproate, and Recurrent Preterm Birth

OBJECTIVE

We sought to evaluate nitric oxide pathway placental gene expression and the epigenome (CpG methylation) among women receiving 17-α hydroxyprogesterone caproate (17-OHPC) with and without recurrent preterm birth (PTB).

STUDY DESIGN

This was a case-control study. We prospectively recruited women with ≥ 1 prior singleton spontaneous PTB <34 weeks receiving 17-OHPC. DNA and RNA were isolated from placentas. RNA abundance (gene expression) and the methylome were analyzed for 84 genes in nitric oxide pathways. Women with recurrent PTB <34 weeks (cases) were compared with those delivering at term (controls). Statistical analysis included multivariable models with Bonferroni's corrected p-values.

RESULTS

In this study, 17 women met inclusion criteria; 7 preterm cases (delivered at 22.6 ± 2.9 weeks) and 10 term controls (delivered at 38.5 ± 0.8 weeks). Groups had similar PTB history, race/ethnicity, and socioeconomic risk factors for PTB. Twenty-seven nitric oxide genes displayed differential expression (p < 0.05 and q < 0.10) when comparing placentas from preterm cases and term controls; all were downregulated in preterm cases. Eight hundred sixty corresponding CpG sites were differentially methylated between the preterm cases and term controls (Bonferroni's p-value <0.05).

CONCLUSION

CpG methylation and gene expression patterns in nitric oxide pathway genes differ among placentas from recurrent PTB compared with term birth following 17-OHPC exposure.

Linking autoimmunity to the origin of the adaptive immune system

In jawed vertebrates, the adaptive immune system (AIS) cooperates with the innate immune system (IIS) to protect hosts from infections. Although targeting non-self-components, the AIS also generates self-reactive antibodies which, when inadequately counter-selected, can give rise to autoimmune diseases (ADs). ADs are on the rise in western countries. Why haven’t ADs been eliminated during the evolution of a ∼500 million-year old system? And why have they become more frequent in recent decades? Self-recognition is an attribute of the phylogenetically more ancient IIS and empirical data compellingly show that some self-reactive antibodies, which are classifiable as elements of the IIS rather then the AIS, may protect from (rather than cause) ADs. Here, we propose that the IIS’s self-recognition system originally fathered the AIS and, as a consequence of this relationship, its activity is dampened in hygienic environments. Rather than a mere breakdown or failure of the mechanisms of self-tolerance, ADs might thus arise from architectural constraints.

In an in-vitro model using human fetal membranes, 17-α hydroxyprogesterone caproate is not an optimal progestogen for inhibition of fetal membrane weakening

BACKGROUND

The progestogen 17-α hydroxyprogesterone caproate (17-OHPC) is 1 of only 2 agents recommended for clinical use in the prevention of spontaneous preterm delivery, and studies of its efficacy have been conflicting. We have developed an in-vitro model to study the fetal membrane weakening process that leads to rupture in preterm premature rupture of the fetal membranes (pPROM). Inflammation/infection associated with tumor necrosis factor-α (TNF-α) induction and decidual bleeding/abruption associated thrombin release are leading causes of preterm premature rupture of the fetal membranes. Both agents (TNF-α and thrombin) cause fetal membrane weakening in the model system. Furthermore, granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical intermediate for both TNF-α and thrombin-induced fetal membrane weakening. In a previous report, we demonstrated that 3 progestogens, progesterone, 17-alpha hydroxyprogesterone (17-OHP), and medroxyprogesterone acetate (MPA), each inhibit both TNF-α- and thrombin-induced fetal membrane weakening at 2 distinct points of the fetal membrane weakening pathway. Each block both the production of and the downstream action of the critical intermediate granulocyte-macrophage colony-stimulating factor.

OBJECTIVE

The objective of the study was to characterize the inhibitory effects of 17-OHPC on TNF-α- and thrombin-induced fetal membrane weakening in vitro.

STUDY DESIGN

Full-thickness human fetal membrane fragments from uncomplicated term repeat cesarean deliveries were mounted in 2.5 cm Transwell inserts and cultured with/without 17-alpha hydroxyprogesterone caproate (10^-9 to 10^-7 M). After 24 hours, medium (supernatant) was removed and replaced with/without the addition of tumor necrosis factor-alpha (20 ng/mL) or thrombin (10 U/mL) or granulocyte-macrophage colony-stimulating factor (200 ng/mL). After 48 hours of culture, medium from the maternal side compartment of the model was assayed for granulocyte-macrophage colony-stimulating factor and the fetal membrane fragments were rupture strength tested.

RESULTS

Tumor necrosis factor-alpha and thrombin both weakened fetal membranes (43% and 62%, respectively) and increased granulocyte-macrophage colony-stimulating factor levels (3.7- and 5.9-fold, respectively). Pretreatment with 17-alpha hydroxyprogesterone caproate inhibited both tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening and concomitantly inhibited the induced increase in granulocyte-macrophage colony-stimulating factor in a concentration-dependent manner. However, contrary to our prior reports regarding progesterone and other progestogens, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced fetal membrane weakening.

CONCLUSION

17-Alpha hydroxyprogesterone caproate blocks tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening by inhibiting the production of granulocyte-macrophage colony-stimulating factor. However, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced weakening. We speculate that progestogens other than 17-alpha hydroxyprogesterone caproate may be more efficacious in preventing preterm premature rupture of the fetal membranes-related spontaneous preterm birth.

Racial and ethnic differences in preterm birth: A complex, multifactorial problem

Preterm birth remains the leading cause of morbidity and mortality among nonanomalous neonates, and is a major public health problem. Non-Hispanic black women have a 2-fold greater risk for preterm birth compared with non-Hispanic white race. The reasons for this disparity are poorly understood and cannot be explained solely by sociodemographic factors. Underlying factors including a complex interaction between maternal, paternal, and fetal genetics, epigenetics, the microbiome, and these sociodemographic risk factors likely underlies the differences between racial groups, but these relationships are currently poorly understood. This article reviews the epidemiology of disparities in preterm birth rates and adverse pregnancy outcomes and discuss possible explanations for the racial and ethnic differences, while examining potential solutions to this major public health problem.

17-alpha hydroxyprogesterone caproate for preterm birth prevention: Where have we been, how did we get here, and where are we going?

Prematurity is a major public health problem in the United States and worldwide. Women with a history of a previous preterm birth are at high risk for recurrence. Progesterone is a key hormone involved in pregnancy maintenance. In general, progesterone is thought to maintain pregnancy through several closely linked mechanisms: (1) promotion of uterine quiescence, (2) inhibition of pro-inflammatory cells, and (3) immunosuppressive action. 17-Alpha hydroxyprogesterone caproate is currently the only medication approved to prevent recurrent preterm birth. The purpose of this review is to discuss the history of 17-alpha hydroxyprogesterone caproate use for recurrent preterm birth prevention, the rationale behind 17-alpha hydroxyprogesterone caproate administration, and current evidence-based indications for 17-alpha hydroxyprogesterone caproate use.

The maternal plasma proteome changes as a function of gestational age in normal pregnancy: a longitudinal study

OBJECTIVE

Pregnancy is accompanied by dramatic physiological changes in maternal plasma proteins. Characterization of the maternal plasma proteome in normal pregnancy is an essential step for understanding changes to predict pregnancy outcome. The objective of this study was to describe maternal plasma proteins that change in abundance with advancing gestational age and determine biological processes that are perturbed in normal pregnancy.

STUDY DESIGN

A longitudinal study included 43 normal pregnancies that had a term delivery of an infant who was appropriate for gestational age without maternal or neonatal complications. For each pregnancy, 3 to 6 maternal plasma samples (median, 5) were profiled to measure the abundance of 1125 proteins using multiplex assays. Linear mixed-effects models with polynomial splines were used to model protein abundance as a function of gestational age, and the significance of the association was inferred via likelihood ratio tests. Proteins considered to be significantly changed were defined as having the following: (1) >1.5-fold change between 8 and 40 weeks of gestation; and (2) a false discovery rate-adjusted value of P < .1. Gene ontology enrichment analysis was used to identify biological processes overrepresented among the proteins that changed with advancing gestation.

RESULTS

The following results were found: (1) Ten percent (112 of 1125) of the profiled proteins changed in abundance as a function of gestational age; (2) of the 1125 proteins analyzed, glypican-3, sialic acid-binding immunoglobulin-type lectin-6, placental growth factor, C-C motif-28, carbonic anhydrase 6, prolactin, interleukin-1 receptor 4, dual-specificity mitogen-activated protein kinase 4, and pregnancy-associated plasma protein-A had more than a 5-fold change in abundance across gestation (these 9 proteins are known to be involved in a wide range of both physiological and pathological processes, such as growth regulation, embryogenesis, angiogenesis immunoregulation, inflammation etc); and (3) biological processes associated with protein changes in normal pregnancy included defense response, defense response to bacteria, proteolysis, and leukocyte migration (false discovery rate, 10%).

CONCLUSION

The plasma proteome of normal pregnancy demonstrates dramatic changes in both the magnitude of changes and the fraction of the proteins involved. Such information is important to understand the physiology of pregnancy and the development of biomarkers to differentiate normal vs abnormal pregnancy and determine the response to interventions.

17-alpha Hydroxyprogesterone caproate did not reduce the rate of recurrent preterm birth in a prospective cohort study

BACKGROUND

17-alpha Hydroxyprogesterone caproate for prevention of recurrent preterm birth is recommended for use in the United States.

OBJECTIVE

We sought to assess the clinical effectiveness of 17-alpha hydroxyprogesterone caproate to prevent recurrent preterm birth ≤35 weeks compared to similar births in our obstetric population prior to the implementation of 17-alpha hydroxyprogesterone caproate.

STUDY DESIGN

This was a prospective cohort study of 17-alpha hydroxyprogesterone caproate in our obstetric population. The primary outcome was the recurrence of birth ≤35 weeks for the entire study cohort compared to a historical referent rate of 16.8% of recurrent preterm birth in our population. There were 3 secondary outcomes. First, did 17-alpha hydroxyprogesterone caproate modify a woman's history of preterm birth when taking into account her prior number and sequence of preterm and term births? Second, was recurrence of preterm birth related to 17-alpha hydroxyprogesterone caproate plasma concentration? Third, was duration of pregnancy modified by 17-alpha hydroxyprogesterone caproate treatment compared to a prior preterm birth?

RESULTS

From January 2012 through March 2016, 430 consecutive women with prior births ≤35 weeks were treated with 17-alpha hydroxyprogesterone caproate. Nearly two thirds of the women (N = 267) began injections ≤18 weeks and 394 (92%) received a scheduled weekly injection within 10 days of reaching 35 weeks or delivery. The overall rate of recurrent preterm birth was 25% (N = 106) for the entire cohort compared to the 16.8% expected rate (P = 1.0). The 3 secondary outcomes were also negative. First, 17-alpha hydroxyprogesterone caproate did not significantly reduce the rates of recurrence regardless of prior preterm birth number or sequence. Second, plasma concentrations of 17-alpha hydroxyprogesterone caproate were not different (P = .17 at 24 weeks; P = .38 at 32 weeks) between women delivered ≤35 weeks and those delivered later in pregnancy. Third, the mean (±SD) interval in weeks of recurrent preterm birth before 17-alpha hydroxyprogesterone caproate use was 0.4 ± 5.3 weeks and the interval of recurrent preterm birth after 17-alpha hydroxyprogesterone caproate treatment was 0.1 ± 4.7 weeks (P = .63). A side effect of weekly 17-alpha hydroxyprogesterone caproate injections was an increase in gestational diabetes. Specifically, the rate of gestational diabetes was 13.4% in 17-alpha hydroxyprogesterone caproate-treated women compared to 8% in case-matched controls (P = .001).

CONCLUSION

17-alpha Hydroxyprogesterone caproate was ineffective for prevention of recurrent preterm birth and was associated with an increased rate of gestational diabetes.

17-α Hydroxyprogesterone Caproate for the Prevention of Recurrent Preterm Birth: One Size May Not Fit All

Spontaneous preterm birth is a syndrome with many causes and thus unresponsive to a single intervention. It logically follows that patients with a prior spontaneous preterm birth are a heterogeneous group unlikely to respond equally to a single preventive intervention such as 17-α hydroxyprogesterone caproate. Further confounding this issue is our fundamental lack of knowledge about the mechanism(s) by which 17-α hydroxyprogesterone caproate reduces preterm birth. Recently, studies demonstrating that responders and nonresponders can be identified based on obstetric history, genotype, physical characteristics, and behavioral factors have begun to provide clues into both 17-α hydroxyprogesterone caproate's mechanism and the pathophysiology of recurrent preterm birth and may allow for more targeted therapy. These studies lend support to speculation that inflammation or nitric oxide metabolism may be common threads between 17-α hydroxyprogesterone caproate's mechanism and preterm birth prevention. It will remain critically important to avoid the temptation to regard prior spontaneous preterm birth as a single disease entity amenable to a single treatment.

Fundamentals of Clinical Pharmacology With Application for Pregnant Women

Medication use is common in pregnancy, yet for most medications the optimal formulation and dosage have not been described specifically for pregnant women. Often, adverse effects are only discovered anecdotally or after extensive off-label use occurs. Since pharmacologic research that includes pregnant women is sparse and animal studies are often not applicable to the human fetus, providers must use knowledge of drug behavior and normal physiologic changes of pregnancy to personalize treatment for pregnant women. In this review, we present an overview of the basic concepts of clinical pharmacology: pharmacokinetics, pharmacodynamics, and pharmacogenomics. The normal physiologic changes of pregnancy are presented as a framework to understand alterations in drug behavior. A clinical vignette that addresses 4 pregnancy scenarios involving medications-preterm birth, vaccination, herpes simplex virus infection, and codeine toxicity-is provided to illustrate application of core clinical pharmacologic concepts. Discussion of relevant literature illustrates the challenges of offering individualized pharmacologic therapy in pregnancy.

Nonresponse to 17-alpha hydroxyprogesterone caproate for recurrent spontaneous preterm birth prevention: clinical prediction and generation of a risk scoring system

BACKGROUND

Spontaneous preterm birth remains a leading cause of neonatal morbidity and mortality among nonanomalous neonates in the United States. Spontaneous preterm birth tends to recur at similar gestational ages. Intramuscular 17-alpha hydroxyprogesterone caproate reduces the risk of recurrent spontaneous preterm birth. Unfortunately, one-third of high-risk women will have a recurrent spontaneous preterm birth despite 17-alpha hydroxyprogesterone caproate therapy; the reasons for this variability in response are unknown.

OBJECTIVE

We hypothesized that clinical factors among women treated with 17-alpha hydroxyprogesterone caproate who suffer recurrent spontaneous preterm birth at a similar gestational age differ from women who deliver later, and that these associations could be used to generate a clinical scoring system to predict 17-alpha hydroxyprogesterone caproate response.

STUDY DESIGN

Secondary analysis of a prospective, multicenter, randomized controlled trial enrolling women with ≥1 previous singleton spontaneous preterm birth <37 weeks' gestation. Participants received daily omega-3 supplementation or placebo for the prevention of recurrent preterm birth; all were provided 17-alpha hydroxyprogesterone caproate. Women were classified as a 17-alpha hydroxyprogesterone caproate responder or nonresponder by calculating the difference in delivery gestational age between the 17-alpha hydroxyprogesterone caproate-treated pregnancy and her earliest previous spontaneous preterm birth. Responders were women with pregnancy extending ≥3 weeks later compared with the delivery gestational age of their earliest previous preterm birth; nonresponders delivered earlier or within 3 weeks of the gestational age of their earliest previous preterm birth. A risk score for nonresponse to 17-alpha hydroxyprogesterone caproate was generated from regression models via the use of clinical predictors and was validated in an independent population. Data were analyzed with multivariable logistic regression.

RESULTS

A total of 754 women met inclusion criteria; 159 (21%) were nonresponders. Responders delivered later on average (37.7±2.5 weeks) than nonresponders (31.5±5.3 weeks), P<.001. Among responders, 27% had a recurrent spontaneous preterm birth (vs 100% of nonresponders). Demographic characteristics were similar between responders and nonresponders. In a multivariable logistic regression model, independent risk factors for nonresponse to 17-alpha hydroxyprogesterone caproate were each additional week of gestation of the earliest previous preterm birth (odds ratio, 1.23; 95% confidence interval, 1.17-1.30, P<.001), placental abruption or significant vaginal bleeding (odds ratio, 5.60; 95% confidence interval, 2.46-12.71, P<.001), gonorrhea and/or chlamydia in the current pregnancy (odds ratio, 3.59; 95% confidence interval, 1.36-9.48, P=.010), carriage of a male fetus (odds ratio, 1.51; 95% confidence interval, 1.02-2.24, P=.040), and a penultimate preterm birth (odds ratio, 2.10; 95% confidence interval, 1.03-4.25, P=.041). These clinical factors were used to generate a risk score for nonresponse to 17-alpha hydroxyprogesterone caproate as follows: black +1, male fetus +1, penultimate preterm birth +2, gonorrhea/chlamydia +4, placental abruption +5, earliest previous preterm birth was 32-36 weeks +5. A total risk score >6 was 78% sensitive and 60% specific for predicting nonresponse to 17-alpha hydroxyprogesterone caproate (area under the curve=0.69). This scoring system was validated in an independent population of 287 women; in the validation set, a total risk score >6 performed similarly with a 65% sensitivity, 67% specificity and area under the curve of 0.66.

CONCLUSIONS

Several clinical characteristics define women at risk for recurrent preterm birth at a similar gestational age despite 17-alpha hydroxyprogesterone caproate therapy and can be used to generate a clinical risk predictor score. These data should be refined and confirmed in other cohorts, and women at high risk for nonresponse should be targets for novel therapeutic intervention studies.

Smoking, 17 Alpha-Hydroxyprogesterone Caproate, and Preterm Birth

Objective The objective of this study was to determine if maternal smoking modifies the effectiveness of 17 α-hydroxyprogesterone caproate (17OHP-C). Study Design Secondary analysis of the Maternal-Fetal Medicine Units Network trial of 17OHP-C. The prevalence of preterm birth (PTB) by smoking status and treatment group was compared by chi-squared analysis and analysis of variance was used to compare gestational age (GA) at birth. Multivariable modeling was used to estimate the effect of smoking on 17OHP-C treatment. Results In this study, 459 women were included. Maternal smoking significantly modified the effectiveness of 17OHP-C treatment. In smokers, 17OHP-C significantly reduced the prevalence of multiple outcomes (PTB < 37 and < 35 weeks, spontaneous PTB < 37 and < 35 weeks), while in nonsmokers, only PTB < 37 weeks was reduced. Delivery GA was later in 17OHP-C versus placebo treated smokers (36.4 vs. 34.3 weeks, p = 0.041) but not nonsmokers (36.3 vs. 35.5 weeks, p = nonsignificant). In multivariable modeling, 17OHP-C was more effective in smokers than nonsmokers as measured by multiple outcomes (PTB < 37 weeks [p = 0.041] and < 35 weeks [p = 0.036] and spontaneous PTB < 37 weeks [p = 0.029]). Conclusion In this cohort of women with a prior PTB, maternal smoking status significantly modified the effectiveness of 17OHP-C treatment.

17-Hydroxyprogesterone caproate (17OHP-C) coverage among eligible women delivering at 2 North Carolina hospitals in 2012 and 2013: A retrospective cohort study

BACKGROUND

Although a weekly injection of 17-hydroxyprogestone caproate is recommended for preventing recurrent preterm birth, clinical experience in North Carolina suggested that many eligible patients were not receiving the intervention.

OBJECTIVE

Our study sought to assess how well practices delivering at 2 major hospitals were doing in providing access to 17-hydroxyprogesterone caproate treatment for eligible patients.

STUDY DESIGN

This retrospective cohort analysis studied all deliveries occurring between January 1, 2012, and December 31, 2013, at 2 large hospitals in North Carolina. Women were included if they had a singleton pregnancy and history of a prior spontaneous preterm birth. We extracted demographic, payer, and medical information on each pregnancy, including whether women had been offered, accepted, and received 17-hydroxyprogesterone caproate. Our outcome of 17-hydroxyprogesterone caproate coverage was defined as documentation of ≥1 injection of the drug.

RESULTS

Over the 2-year study period, 1216 women with history of a prior preterm birth delivered at the 2 study hospitals, of which 627 were eligible for 17-hydroxyprogesterone caproate eligible after medical record review. Only 296 of the 627 eligible women (47%; 95% confidence interval, 43-51%) received ≥1 dose of the drug. In multivariable analysis, hospital of delivery, later presentation for prenatal care, fewer prenatal visits, later gestation of prior preterm birth, and having had a term delivery immediately before the index pregnancy were all associated with failed coverage. Among those women who were "covered," the median number of 17-hydroxyprogesterone caproate injections was 9 (interquartile range, 4-15), with 84 of 296 charts (28%) not having complete information on the number of doses.

CONCLUSION

Even under our liberal definition of coverage, less than half of eligible women received 17-hydroxyprogesterone caproate in this sample. Low overall use suggests that there is opportunity for improvement. Quality improvement strategies, including population-based measurement of 17-hydroxyprogesterone caproate coverage, are needed to fully implement this evidence-based intervention to decrease preterm birth.