Why the United States preterm birth rate is declining

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 Following a recent negative confirmatory trial, 17-alpha hydroxyprogesterone caproate was withdrawn from the US market and is currently available only through clinical research studies.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 High-Grade Squamous Intraepithelial Lesion Burden and Standard of Care Treatment Effectiveness and Safety in the United States, 2008-2018: The EACH-WOMAN Project

OBJECTIVE

Management of cervical high-grade squamous intraepithelial lesions (HSILs), the immediate precursor of cervical cancer, consists largely of surgical treatment for women at higher risk for progression to cancer. The authors' objective was to describe the occurrence of cervical HSIL in the United States and various outcomes for women who received surgical treatment.

METHODS

From a US commercial health insurer, a cohort of adult women with cervical HSIL diagnoses receiving surgical treatment within 3 months of diagnosis between January 2008 and September 2018 was identified. This cohort was followed for several outcomes, including cervical HSIL recurrence, human papillomavirus clearance, preterm birth, infection, and bleeding.

RESULTS

The incidence rate of cervical HSIL declined from 2.34 (95% CI = 2.30-2.39) cases per 1,000 person-years in 2008 to 1.39 (95% CI = 1.35-1.43) cases per 1,000 person-years in 2014, remaining near that level through 2018. Among 65,527 women with cervical HSIL, 47,067 (72%) received surgical treatment within 3 months of diagnosis. Among the women receiving surgical treatment, cervical HSIL recurred in 6% of surgically treated women, whereas 45% of surgically treated women underwent subsequent virological testing that indicated human papillomavirus clearance. Preterm birth was observed in 5.9% by 5 years follow-up and bleeding and infection each at 2.2% by 7 days follow-up.

CONCLUSIONS

From 2008 through 2018, the incidence of diagnosed cervical HSIL decreased for several years before stabilizing. Surgical treatment of HSIL may be beneficial in removing the precancerous lesion, but cervical HSIL may recur, and the surgery is associated with complications including preterm birth, infection, and bleeding.

Trends in Spontaneous and Medically Indicated Preterm Birth in Twins versus Singletons: A California Cohort 2007 to 2011

OBJECTIVE

The study aimed to describe preterm birth (PTB) rates, subtypes, and risk factors in twins compared with singletons to better understand reasons for the decline in PTB rate between 2007 and 2011.

STUDY DESIGN

This was a retrospective population-based analysis using the California linked birth certificates and maternal-infant hospital discharge records from 2007 to 2011. The main outcomes were overall, spontaneous (following spontaneous labor or preterm premature rupture of membranes), and medically indicated PTB at various gestational age categories: <37, <32, and 34 to 36 weeks in twins and singletons.

RESULTS

Among the 2,290,973 singletons and 28,937 twin live births pairs included, overall PTB <37 weeks decreased by 8.46% (6.77-6.20%) in singletons and 7.17% (55.31-51.35%) in twins during the study period. In singletons, this was primarily due to a 24.91% decrease in medically indicated PTB with almost no change in spontaneous PTB, whereas in twins indicated PTB declined 7.02% and spontaneous PTB by 7.39%.

CONCLUSION

Recent declines in PTB in singletons appear to be largely due to declines in indicated PTB, whereas both spontaneous and indicated PTB declined in twins.

KEY POINTS

· The declines in PTB noted between 2006 and 2014 occurred in both singleton and twins.. · Declines were mostly in medically indicated PTB.. · Interventions proposed as causing the declines in singletons would not apply to twins..

Concentration of vaginal and systemic cytokines obtained early in pregnancy and their impact on preterm birth

OBJECTIVE

A number of factors can lead to a maternal pro-inflammatory response resulting in a spontaneous preterm birth. However, it remains unknown if an upregulation in the maternal immune system early in pregnancy leads to an increase in pro-inflammatory cytokines and ultimately preterm birth. Therefore, we hypothesize an increase in vaginal and systemic pro-inflammatory cytokines early pregnancy is associated with an increased risk of preterm birth.

STUDY DESIGN

Patients initiating prenatal care prior to 14 weeks gestation were recruited for eligibility. A vaginal swab and serum sample was obtained at the first prenatal visit and these were then stored at -80 C. Patients were then followed for their gestational age at delivery. Five patients delivering preterm (cases) were matched with ten patients delivering at term (controls) based on age, BMI, smoking status and ethnicity. The serum and vaginal swabs from the cases and controls were then analyzed for the following cytokines using a multiplex cytokine assay: GM-CSF, IL-1b, IL-6, TNFα, and Rantes.

RESULTS

A total of 116 patients were screened for eligibility and 96 of these patients had samples obtained prior to 14 weeks gestation. Of these 96, 5 had a spontaneous preterm birth and these were matched to 10 controls. There was no difference detected in the cytokine concentrations of GM-CSF, IL-1b, IL-6, TNFα, and Rantes in the serum or cervicovaginal fluid between cases and controls.

CONCLUSION

This study demonstrates there is no difference in cytokine concentrations of several pro-inflammatory cytokines in the vagina or in the serum prior to 14 weeks gestation in patients delivering preterm. Therefore, the concentration of the cytokines analyzed in this study from the vagina and serum have little predictive value on the risk of preterm birth. Further research is needed to deepen our understanding of the mechanisms leading to preterm birth.

Characteristics of Women Receiving Emergency Caesarean Section: A Cross-Sectional Analysis from Ghana and Dominican Republic

BACKGROUND

Significant inequalities still exist between low- and high-income countries regarding access to optimum emergency obstetric care including life-saving emergency caesarean section. These relationships are considerably stronger between population-based caesarean section rates and socio-economic characteristics with poorest households experiencing significant unmet needs persistently.

OBJECTIVE

To explore the characteristics of women receiving emergency C-section using a new, validated definition in Ghana and the Dominican Republic.

MATERIALS AND METHODS

This was a cross-sectional study conducted in Ghana and the Dominican Republic. Multivariable logistic regression analysis was used to determine women's characteristics associated with emergency C-section.

RESULTS

This analysis included 2166 women who had recently delivered via C-section comprising 653 and 1513 participants from Accra and Santo Domingo, DR, respectively. Multivariable analyses showed that women, both in Ghana and the DR, were more likely to have an emergency C-section if they did not have a previous C-Section (adjusted Odds Ratio (aOR): 2.45, 95% CI [1.57-3.81]; and aOR: 15.5, 95% CI [10.5-22.90], respectively) and if they were having their first childbirth, compared to women with previous childbirth (aOR: 1.77, 95%CI [1.13-2.79]; and aOR: 1.46, 95%CI [1.04-2.04], respectively). Also, preterm birth was associated with significantly decreased likelihood of emergency C-section compared with childbirth occurring at term in both Ghana and the DR (aOR: 0.31, 95%CI [0.20-0.48]; and aOR: 0.43, 95%CI [0.32-0.58], respectively). Among the Ghanaian participants, having an emergency C-section was positively associated with being referred and negatively associated with being older than 35 years of age. Characteristics such as education, religion, marital status, and residence did not differ between women's emergency versus non-emergency C-section status.

CONCLUSION

Emergency C-section was found to be significantly higher in women with no prior C-section or those having their first births but lower in those with preterm birth in both Ghana and the DR. Data from additional countries are needed to confirm the relationship between emergency C-section status and socio-economic and obstetric characteristics, given that the types of interventions required to assure equitable access to potentially life-saving C-section will be determined by how and when access to care is being denied or not available.

Granulocyte-macrophage colony-stimulating factor initiates amniotic membrane rupture and preterm birth in a mouse model

OBJECTIVE

Preterm premature rupture of membranes is associated with 30% of all preterm births. The weakening of amniotic membranes is associated with an increase in matrix metallopeptidases (MMPs) along with a decrease in their inhibitors, tissue inhibitor metallopeptidases (TIMPs). Additionally, granulocyte-macrophage colony-stimulating factor (GM-CSF) has been shown to weaken fetal membranes in-vitro. We hypothesize pregnant mice treated with GM-CSF lead to increased MMPs:TIMPs resulting in membrane rupture and preterm birth.

STUDY DESIGN

Pregnant CD-1 mice on gestational day 17 received either an intrauterine injection of GM-CSF or vehicle control. A second series of mice were administered an intrauterine injection of Lipopolysaccharide along with either anti-mouse GM-CSF or control antibody. Mice were evaluated for rupture of membranes and/or preterm birth and the uterus, amniotic fluid, and serum were collected for analysis.

RESULTS

87.5% of GM-CSF mice exhibited evidence of membrane rupture or preterm birth, compared with 0% in control mice (p < .001). Treatment with GM-CSF decreased the expression of TNFα (p < .05) while increasing the ratio of MMP2:TIMP1 (p < .05), MMP2:TIMP2 (p < .05), MMP2:TIMP3 (p < .001), MMP9:TIMP1 (p < .01), MMP9:TIMP2 (p < .05), MMP9:TIMP3 (p < .001), and MMP10:TIMP1 (p < .05). Mice treated with LPS and the GM-CSF antibody resulted in a decrease in the ratio of MMP2:TIMP1 (p < .0001) compared with controls.

CONCLUSION

These studies demonstrate GM-CSF will result in membrane rupture and preterm birth by increasing the ratio MMPs:TIMPs in our animal model. By increasing our understanding of the molecular pathways associated with GM-CSF, we may be able to develop future therapies to prevent preterm birth and reduce neonatal morbidity.

Decidual cell FKBP51-progesterone receptor binding mediates maternal stress-induced preterm birth

Depression and posttraumatic stress disorder increase the risk of idiopathic preterm birth (iPTB); however, the exact molecular mechanism is unknown. Depression and stress-related disorders are linked to increased FK506-binding protein 51 (FKBP51) expression levels in the brain and/or FKBP5 gene polymorphisms. Fkbp5-deficient (Fkbp5 ^-/-) mice resist stress-induced depressive and anxiety-like behaviors. FKBP51 binding to progesterone (P4) receptors (PRs) inhibits PR function. Moreover, reduced PR activity and/or expression stimulates human labor. We report enhanced in situ FKBP51 expression and increased nuclear FKBP51-PR binding in decidual cells of women with iPTB versus gestational age-matched controls. In Fkbp5 ^+/+ mice, maternal restraint stress did not accelerate systemic P4 withdrawal but increased Fkbp5, decreased PR, and elevated AKR1C18 expression in uteri at E17.25 followed by reduced P4 levels and increased oxytocin receptor (Oxtr) expression at 18.25 in uteri resulting in PTB. These changes correlate with inhibition of uterine PR function by maternal stress-induced FKBP51. In contrast, Fkbp5 ^-/- mice exhibit prolonged gestation and are completely resistant to maternal stress-induced PTB and labor-inducing uterine changes detected in stressed Fkbp5 ^+/+ mice. Collectively, these results uncover a functional P4 withdrawal mechanism mediated by maternal stress-induced enhanced uterine FKBP51 expression and FKPB51-PR binding, resulting in iPTB.

Delivering equity: preterm birth by socioeconomic class before and after coverage of 17-hydroxyprogesterone caproate

OBJECTIVE

We compare the preterm birth rate across socioeconomic strata in Michigan before and after the decision by Michigan Medicaid to provide coverage for 17-hydroxyprogesterone caproate (17-OHP), a costly medication for recurrent preterm birth prevention.

STUDY DESIGN

We retrospectively analyzed births recorded in the Michigan Department of Health & Human Services database from 2008-2016, comparing the rate of preterm birth stratified by standardized US Census Bureau socioeconomic levels (affluent, higher-middle class, lower-middle class, and poverty) across three time periods: pre-Federal Drug Administration approval of 17-OHP (2008-2011), pre-Medicaid coverage (2012-2014), and post-Medicaid coverage (2015-2016).

RESULTS

Of 1,034,901 total live births, 10% (N = 103,869) were premature. An ANOVA with post-hoc testing showed the preterm birth rate was highest for those living in poverty, lower for the lower-middle class, and lowest for the collective higher-middle and affluent classes. The preterm birth rate dropped for all classes after Michigan Medicaid began paying for 17-OHP, but inter-class gaps remained.

CONCLUSION

Extended financial coverage for 17-OHP may have contributed to modest decreases in preterm birth rates, but this policy did not equalize outcomes between those with disparate resources.

Does maternal race or ethnicity modify the association between maternal psychiatric disorders and preterm birth?

PURPOSE

Preterm birth risk has been linked to maternal racial and ethnic background, particularly African American heritage; however, the association of maternal race and ethnicity with psychiatric disorders and preterm birth has received relatively limited attention.

METHODS

The Consortium on Safe Labor (2002-2008) is a nationwide U.S. cohort study with 223,394 singleton pregnancies. Clinical data were obtained from electronic medical records, including maternal diagnoses of psychiatric disorders. Relative risk (RR) and 95% confidence intervals (CI) were estimated for the association between maternal psychiatric disorders and preterm birth (<37 completed weeks) using log-binomial regression with generalized estimating equations. The interaction effect of maternal psychiatric disorders with race and ethnicity was also evaluated.

RESULTS

Non-Hispanic White (RR, 1.42; 95% CI, 1.35-1.49), Hispanic (RR, 1.44; 95% CI, 1.29-1.60), and non-Hispanic Black (RR, 1.21, 95% CI, 1.13-1.29) women with any psychiatric disorder were at increased risk for delivering preterm infants, compared with women without any psychiatric disorder. However, non-Hispanic Black women with any psychiatric disorder, depression, bipolar disorder, and schizophrenia had a significantly lower increase in preterm birth risk than non-Hispanic White women.

CONCLUSIONS

Despite the significant association between maternal psychiatric disorders and preterm birth risk, psychiatric disorders did not appear to contribute to racial and ethnic disparities in preterm birth.

The Proximity of Spatial Clusters of Low Birth Weight and Risk Factors: Defining a Neighborhood for Focused Interventions

BACKGROUND

Low birth weight (LBW) is associated with significant mortality and morbidity and remains a significant preventable problem. Risk factors include socioeconomic, demographics, and characteristics of the environment. Spatial analysis can uncover unusual frequencies of health problems in neighborhoods, eventually leading to insights for targeted interventions.

OBJECTIVES

This study's goals were to 1. Evaluate the geographic distribution of spatial clusters of LBW births and maternal risk factors. 2. Determine the spatial relationship between risk factors and LBW.

METHODS

This study obtained data on LBW newborns and risk factors from 19,013 births over 5 years (2012-2016) for Escambia County Census Tracts, extracted from FloridaCharts.com. Software was used to detect significant spatial clusters; these clusters were then plotted on a map. Poisson regression determined the statistical relationship between Census Tract risk factors and LBW. A separate analysis of the LBW cluster controlling for risk factors was also performed.

RESULTS

All risk factor clusters resided in similar locations as the LBW cluster. The multiple Poisson regression model containing all risk factors fully explained the LBW cluster. On bivariate Poisson regression all risk factors in the Census Tract were significantly related to LBW whereas in multivariable Poisson regression, the proportion of births to African American women in the Census Tract remained significant after adjusting for other risk factors (p < 0.001).

CONCLUSIONS FOR PRACTICE

Clusters of LBW and risk factors were located in the same region of the county, with the proportion of births to African American women in the Census Tract remaining significant on multiple Poisson Regression. Targeted interventions should be directed at the geographic level.

Trends in preterm birth: an academic center's campaign to reduce the incidence

Objective: To evaluate if the implementation of five protocols aimed at reducing the preterm birth rate were associated with a decrease in incidence of PTBs at an academic center.Methods: This is an observational study of women with singleton gestations delivered at TJUH between 2004 and 2014. Primary outcome was the annual incidence of PTB <37 weeks at TJUH. Secondary outcome was the rate of change for PTBs at TJUH compared against that of the nation. Linear regression, Pearson correlation coefficients, and t-tests were used to analyze preterm birth rates over time.Results: TJUH incidence of PTB < 37 weeks significantly decreased from 10.8% (n = 206) in 2004 to 9.1% (n = 169) in 2014 (p = .001). Linear regression showed a dramatically greater rate of decline at TJUH (0.32% per year, p = .001) compared to that of the USA (0.14% per year, p < .0001). Early PTBs (28-33 6/7 week) at TJUH had the steepest rate of decline at 0.13% per year (p = .001). Late PTBs (34-36 6/7 week) at TJUH were the only group to not have a significant rate of decline (p = .114).Conclusion: The incidence of PTBs at TJUH decreased more than the USA national average in the study period, which may be due to early adoption of guidelines for prevention of PTB.Condensation: The incidence of PTBs at TJUH decreased more than the USA national average in the study period, which may be due to early adoption of guidelines for prevention of PTB.

The impact of heat exposure on reduced gestational age in pregnant women in North Carolina, 2011-2015

Research on the impact of heat on pregnant women has focused largely on outcomes following extreme temperature events, such as particular heat waves or spells of very cold weather on pregnant women. Consistently, the literature has shown a statistically significant relationship between heat with shortened gestational age with studies concentrated largely in the western states of the USA or other nations. The association between heat and shortened gestational age has not been examined in the Southeastern US where maternal outcomes are some of the most challenging in the nation. Unlike previous studies that focus on the impacts of a single heat wave event, this study seeks to understand the impact of high heat over a 5-year period during the annual warm season (May-September). To achieve this goal, a case-crossover study design is employed to understand the impact of heat on preterm labor across regions in North Carolina (NC). Temperature thresholds for impact and the underlying relationships between preterm labor and heat are investigated using generalized additive models (GAM). Gridded temperature data (PRISM) is used to establish exposure classifications. The results reveal significant impacts to pregnant women exposed to heat with regional variations. The exposure variable with the most stable and significant result was minimum temperature, indicating high overnight temperatures have the most impact on preterm birth. The magnitude of this impact varies across regions from a 1% increase in risk to 6% increase in risk per two-degree increment above established minimum temperature thresholds.

ACOG Committee Opinion No. 765: Avoidance of Nonmedically Indicated Early-Term Deliveries and Associated Neonatal Morbidities

There are medical indications in pregnancy for which there is evidence or expert opinion to support delivery versus expectant management in the early-term period. However, the risk of adverse outcomes is greater for neonates delivered in the early-term period compared with neonates delivered at 39 weeks of gestation. In addition to immediate adverse perinatal outcomes, multiple studies have shown increased rates of adverse long-term infant outcomes associated with late-preterm and early-term delivery compared with full-term delivery. A recent systematic review found that late-preterm and early-term children have lower performance scores across a range of cognitive and educational measures compared with their full-term peers. Further research is needed to better understand if these differences are primarily based on gestational age at delivery versus medical indications for early delivery. Documentation of fetal pulmonary maturity alone does not necessarily indicate that other fetal physiologic processes are adequately developed. For this reason, amniocentesis for fetal lung maturity is not recommended to guide timing of delivery, even in suboptimally dated pregnancies. Avoidance of nonmedically indicated delivery before 39 0/7 weeks of gestation is distinct from, and should not result in, an increase in expectant management of patients with medical indications for delivery before 39 0/7 weeks of gestation. Management decisions, therefore, should balance the risks of pregnancy prolongation with the neonatal and infant risks associated with early-term delivery. Although there are specific indications for delivery before 39 weeks of gestation, a nonmedically indicated early-term delivery should be avoided. This document is being revised to reflect updated data on nonmedically indicated early-term deliveries.

The efficacy of cervical cerclage combined with a pessary for the prevention of spontaneous preterm birth

AIMS

This study compared the effectiveness and safety of cervical cerclage combined with cervical pessary in the treatment of cervical incompetence and that of cervical cerclage alone and cervical pessary alone.

METHODS

We performed a prospective cohort study of women with cervical incontinence. Subjects were randomized into three groups: cerclage, pessary, and cerclage and pessary combined.

RESULTS

A total of 75 patients with cervical incompetence were enrolled: 37.3% patients had a cervical length <15 mm, and 62.5% had a cervical length of 15-25 mm. Patients with increased body mass index were significantly likely to have a short cervix (p = .06); patients with a short cervix had earlier rupture of the membrane. The cerclage and pessary groups had more spontaneous abortions than the combined treatment group, which had no abortions or premature births. The mean gestational ages at delivery for the cerclage group (37.82 weeks) and the pessary group (35.73 weeks) were smaller than for the combined treatment group (38.33 weeks). The premature rupture of membranes that was correlated with cervical length had a higher incidence in the pessary group (26.9%).

CONCLUSION

Placement of a cervical cerclage combined with a cervical pessary is a safe technique and has a high success rate in the treatment of cervical incompetence.

Practical considerations with 17-Hydroxyprogesterone caproate for preterm birth prevention: does timing of initiation and compliance matter?

OBJECTIVE

Determine whether gestational age of 17-hydroxyprogesterone caproate (17-OHPC) initiation is associated with preterm birth (PTB) risk.

STUDY DESIGN

We performed a retrospective cohort study using MarketScan® data. The primary outcome was PTB < 37 weeks. Rates of PTB were compared between medication initiation at 16-21 weeks versus 21-29 weeks. The association between compliance with weekly 17-OHPC injections and preterm birth rate was tested after adjusting for potential confounding variables.

RESULT

In all 3374 pregnancies met inclusion criteria. Women with an early 17-OHPC start were less likely to deliver preterm than those with a late start (aRR 0.88; 95%CI 0.79-0.97; p = 0.02). Less compliant patients receiving <25% of recommended doses had a higher PTB rate than those receiving >85% of recommended doses (aRR 1.5; 95%CI 1.2-1.7; p < 0.01).

CONCLUSION

There is an association between both early 17-OHPC initiation and compliance with reduced rates of PTB.

A systematic review and meta-analysis of randomized controlled trials comparing 17-alpha-hydroxyprogesterone caproate versus placebo for the prevention of recurrent preterm birth

BACKGROUND

Preterm birth causes an increased risk for perinatal morbidity and mortality.

OBJECTIVE

To determine whether mid-trimester 17-alpha-hydroxyprogesterone caproate (17-OHPC) reduces the risk of recurrent preterm birth and adverse perinatal outcomes.

SEARCH STRATEGY

Systematic search to identify relevant studies published in different languages, registered after 2000, using appropriate MeSH terms.

SELECTION CRITERIA

Inclusion criteria were women between 16 and 26⁺⁶  weeks of pregnancy with history of preterm delivery in any pregnancy randomized to either 17-OHPC or placebo/no treatment.

DATA COLLECTION AND ANALYSIS

The number of preterm births and adverse outcomes in the 17-OHPC and placebo arms over the total number of patients in each randomized group were used to calculate the risk ratio (RR) by random-effects models using the Mantel-Haenszel method. Between-study heterogeneity was assessed using tau² , χ² (Cochrane Q), and I² statistics.

MAIN RESULTS

Four studies were included. There was a 29% (RR 0.71; 95% CI, 0.53-0.96; P=0.001), 26% (RR 0.74; 95% CI, 0.58-0.96; P=0.021), and 40% (RR 0.60; 95% CI, 0.42-0.85; P=0.004) reduction in recurrent preterm birth at <37, <35, and <32 weeks, respectively, in the 17-OHPC group compared with placebo. The reduction in neonatal death was 68% (RR 0.32; 95% CI, 0.15-0.66; P=0.002).

CONCLUSIONS

17-OHPC could reduce the risk of recurrent preterm birth at <37, <35, and <28 weeks and neonatal death.

PROSPERO

CDR42017082190.

The association between 17-hydroxyprogesterone caproate use and postpartum hemorrhage

OBJECTIVE

To evaluate whether receipt of 17α-hydroxyprogesterone caproate within seven days of delivery is associated with increased risk of postpartum hemorrhage.

STUDY DESIGN

This was a retrospective cohort study of women who were receiving 17α-hydroxyprogesterone caproate for preterm birth prevention and delivered between 2010 and 2014. Women were dichotomized by whether a dose of 17α-hydroxyprogesterone caproate was administered within seven days of delivery. Demographic and clinical characteristics were examined, including obstetric history and details of 17α-hydroxyprogesterone caproate receipt. Bivariable analyses were used to compare the frequency of postpartum hemorrhage in women stratified by 17α-hydroxyprogesterone caproate receipt within seven days of delivery. Multivariable analysis was used to adjust for potential confounders.

RESULTS

Of 221 women who met inclusion criteria, 93 (42%) received 17α-hydroxyprogesterone caproate within seven days of delivery and 18 (7.8%) experienced a postpartum hemorrhage. No differences were observed in the frequency of postpartum hemorrhage between women who did and did not deliver within seven days of 17α-hydroxyprogesterone caproate injection (9.7% vs 7.0%, p=0.478). These findings persisted after adjusting for potential confounders (aOR for PPH 2.9, 95% CI, 0.5-15.8).

CONCLUSION

Recent receipt of 17α-hydroxyprogesterone caproate for prevention of recurrent preterm birth is not associated with risk of postpartum hemorrhage.

International variations in the gestational age distribution of births: an ecological study in 34 high-income countries

Background

Few studies have investigated international variations in the gestational age (GA) distribution of births. While preterm births (22-36 weeks GA) and early term births (37-38 weeks) are at greater risk of adverse health outcomes compared to full term births (39-40 weeks), it is not known if countries with high preterm birth rates also have high early term birth rates. We examined rate associations between preterm and early term births and mean term GA by mode of delivery onset.

Methods

We used routine aggregate data on the GA distribution of singleton live births from up to 34 high-income countries/regions in 1996, 2000, 2004, 2008 and 2010 to study preterm and early term births overall and by spontaneous or indicated onset. Pearson correlation coefficients were adjusted for clustering in time trend analyses.

Results

Preterm and early term births ranged from 4.1% to 8.2% (median 5.5%) and 15.6% to 30.8% (median 22.2%) of live births in 2010, respectively. Countries with higher preterm birth rates in 2004-2010 had higher early term birth rates (r > 0.50, P < 0.01) and changes over time were strongly correlated overall (adjusted-r = 0.55, P < 0.01) and by mode of onset.

Conclusion

Positive associations between preterm and early term birth rates suggest that common risk factors could underpin shifts in the GA distribution. Targeting modifiable population risk factors for delivery before 39 weeks GA may provide a useful preterm birth prevention paradigm.

The associations between prenatal exposure to triclocarban, phenols and parabens with gestational age and birth weight in northern Puerto Rico

BACKGROUND

Prenatal exposure to certain xenobiotics has been associated with adverse birth outcomes. We examined the associations of triclocarban, phenols and parabens in a cohort of 922 pregnant women in Puerto Rico, the Puerto Rico Testsite for Exploring Contamination Threats Program (PROTECT).

METHODS

Urinary triclocarban, phenols and parabens were measured at three time points in pregnancy (visit 1: 16-20 weeks, visit 2: 20-24 weeks, visit 3: 24-28 weeks gestation). Multiple linear regression (MLR) models were conducted to regress gestational age and birthweight z-scores against each woman's log average concentrations of exposure biomarkers. Logistic regression models were conducted to calculate odds of preterm birth, small or large for gestational age (SGA and LGA) in association with each of the exposure biomarkers. An interaction term between the average urinary biomarker concentration and infant sex was included in models to identify effect modification. The results were additionally stratified by study visit to look for windows of vulnerability. Results were transformed into the change in the birth outcome for an inter-quartile-range difference in biomarker concentration (Δ).

RESULTS

Average benzophenone-3, methyl- and propyl-paraben concentrations were associated with an increase in gestational age [(Δ 1.90 days; 95% CI: 0.54, 3.26); (Δ 1.63; 95% CI: 0.37, 2.89); (Δ 2.06; 95% CI: 0.63, 3.48), respectively]. Triclocarban was associated with a suggestive 2-day decrease in gestational age (Δ - 1.96; 95% CI: -4.11, 0.19). Bisphenol A measured at visit 1 was associated with a suggestive increase in gestational age (Δ 1.37; 95% CI: -0.05, 2.79). Triclosan was positively associated with gestational age among males, and negatively associated with gestational age among females. Methyl-, butyl- and propyl-paraben were associated with significant 0.50-0.66 decreased odds of SGA. BPS was associated with an increase in the odds of SGA at visit 3, and a suggestive increase in the odds of LGA at visit 1.

CONCLUSION

Benzophenone-3, methyl-paraben and propyl-paraben were associated with an increase in gestational age. Concentrations of triclocarban, which were much higher than reported in other populations, were associated with a suggestive decrease in gestational age. The direction of the association between triclosan and gestational age differed by infant sex. Parabens were associated with a decrease in SGA, and BPS was associated with both SGA and LGA depending on the study visit. Further studies are required to substantiate these findings.

Temporal trends in neonatal mortality and morbidity following spontaneous and clinician-initiated preterm birth in Washington State, USA: a population-based study

OBJECTIVE

After a decade of increase, the preterm birth (PTB) rate has declined in the USA since 2006, with the largest decline at late preterm (34-36 weeks). We described concomitant changes in gestational age-specific rates of neonatal mortality and morbidity following spontaneous and clinician-initiated PTB among singleton infants.

DESIGN, SETTING AND PARTICIPANTS

This retrospective population-based study included 754 763 singleton births in Washington State, USA, 2004-2013, using data from birth certificates and hospitalisation records. PTB subtypes included preterm premature rupture of membranes (PPROM), spontaneous onset of labour and clinician-initiated delivery.

OUTCOME MEASURES

The primary outcomes were neonatal mortality and a composite outcome including death or severe neonatal morbidity. Temporal trends in the outcomes and individual morbidities were assessed by PTB subtype. Logistic regression yielded adjusted odds ratios (AOR) per 1 year change in outcome and 95% CI.

RESULTS

The rate of PTB following PPROM and spontaneous labour declined, while clinician-initiated PTB increased (all p<0.01). Overall neonatal mortality remained unchanged (1.3%; AOR 0.99, CI 0.95 to 1.02), though gestational age-specific mortality following clinician-initiated PTB declined at 32-33 weeks (AOR 0.85, CI 0.74 to 0.97) and increased at 34-36 weeks (AOR 1.10, CI 1.01 to 1.20). The overall rate of the composite outcome increased (from 7.9% to 11.9%; AOR 1.06, CI 1.05 to 1.08). Among late preterm infants, combined mortality or severe morbidity increased following PPROM (AOR 1.13, CI 1.08 to 1.18), spontaneous labour (AOR 1.09, CI 1.06 to 1.13) and clinician-initiated delivery (AOR 1.10, CI 1.07 to 1.13). Neonatal sepsis rates increased among all preterm infants (AOR 1.09, CI 1.08 to 1.11).

CONCLUSIONS

Timing of obstetric interventions is associated with infant health outcomes at preterm. The temporal decline in late PTB among singleton infants was associated with increased mortality among late preterm infants born following clinician-initiated delivery and increased combined mortality or severe morbidity among all late preterm infants, mainly due to increased rate of sepsis.

Preterm birth in relation to the bisphenol A replacement, bisphenol S, and other phenols and parabens

INTRODUCTION

Preterm birth continues to be a significant public heath concern and is a leading cause of perinatal and infant mortality. Environmental exposures to phenols and parabens are suspected to potentially contribute to the pathology of preterm birth, yet limited human studies have characterized the extent to which these toxicants are associated with birth outcomes.

METHODS

We examined the associations between phenols, parabens, and preterm birth, within pregnant women who were recruited early in gestation into the LIFECODES cohort at Brigham and Women's Hospital in Boston, Massachusetts. Urine samples were collected at up to 4 time points in pregnancy and analyzed for phenols and parabens. We selected 130 cases of preterm birth (defined as delivery before 37 weeks gestation), and 350 random controls. We categorized preterm birth subtypes based on clinical presentation and identified 75 cases of spontaneous preterm birth (characterized by spontaneous preterm labor and/or preterm premature rupture of membranes), and 37 cases of placental preterm birth (characterized by preeclampsia and/or intrauterine growth restriction). We used multivariate logistic regression with visit specific and geometric averages of phenols and parabens to determine associations with preterm birth.

RESULTS

We observed moderate variability in urinary phenol and paraben concentrations over pregnancy with intraclass correlation coefficients ranging between 0.45 and 0.68. Regression analyses indicated mostly null associations. We observed inverse associations, notably between 2,5-dichlorophenol and overall preterm birth (adjusted odds ratio [95% confidence interval, CI]: 0.79 [0.67 - 0.94]), and this relationship was consistent by study visit. Conversely, ethyl paraben was associated with increased risk for placental preterm birth (adjusted odds ratio [95% CI]: 1.47 [1.14 - 1.91]). Bisphenol-S detection at visit 4 was associated with overall preterm birth (adjusted odds ratio [95% CI]: 2.05 [1.09, 3.89]).

CONCLUSIONS

While the findings from this study largely indicate null associations, we observed some relationships between select phenols, parabens and preterm birth, which warrants further investigation of these toxicants and birth outcomes.

Temporal trends, patterns, and predictors of preterm birth in California from 2007 to 2016, based on the obstetric estimate of gestational age

Background

Preterm birth (PTB) is associated with increased infant mortality, and neurodevelopmental abnormalities among survivors. The aim of this study is to investigate temporal trends, patterns, and predictors of PTB in California from 2007 to 2016, based on the obstetric estimate of gestational age (OA).

Methods

A retrospective cohort study evaluated 435,280 PTBs from the 5,137,376 resident live births (8.5%) documented in the California Birth Statistical Master Files (BSMF) from 2007 to 2016. The outcome variable was PTB; the explanatory variables were birth year, maternal characteristics and health behaviors. Descriptive statistics and logistic regression analysis were used to identify subgroups with significant risk factors associated with PTB. Small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) infants were identified employing gestational age based on obstetric estimates and further classified by term and preterm births, resulting in six categories of intrauterine growth.

Results

The prevalence of PTB in California decreased from 9.0% in 2007 to 8.2% in 2014, but increased during the last 2 years, 8.4% in 2015 and 8.5% in 2016. Maternal age, education level, race and ethnicity, smoking during pregnancy, and parity were significant risk factors associated with PTB. The adjusted odds ratio (AOR) showed that women in the oldest age group (40–54 years) were almost twice as likely to experience PTB as women in the 20- to 24-year reference age group. The prevalence of PTB was 64% higher in African American women than in Caucasian women. Hispanic women showed less disparity in the prevalence of PTB based on education and socioeconomic level. The analysis of interactions between maternal characteristics and perinatal health behaviors showed that Asian women have the highest prevalence of PTB in the youngest age group (< 20 years; AOR, 1.40; 95% confidence interval (CI), 1.28–1.54). Pacific Islander, American Indian, and African American women ≥40 years of age had a greater than two-fold increase in the prevalence of PTB compared with women in the 20–24 year age group. Compared to women in the Northern and Sierra regions, women in the San Joaquin Valley were 18%, and women in the Inland Empire and San Diego regions 13% more likely to have a PTB. Women who smoked during both the first and second trimesters were 57% more likely to have a PTB than women who did not smoke. Compared to women of normal prepregnancy weight, underweight women and women in obese class III were 23 and 33% more likely to experience PTB respectively.

Conclusions

Implementation of public health initiatives focusing on reducing the prevalence of PTB should focus on women of advanced maternal age and address race, ethnic, and geographic disparities. The significance of modifiable maternal perinatal health behaviors that contribute to PTB, e.g. smoking during pregnancy and prepregnancy obesity, need to be emphasized during prenatal care.

Electronic supplementary material

The online version of this article (10.1186/s40748-018-0094-0) contains supplementary material, which is available to authorized users.

Association Between Temporal Changes in Neonatal Mortality and Spontaneous and Clinician-Initiated Deliveries in the United States, 2006-2013

IMPORTANCE

Preterm and postterm deliveries have declined since 2005 in the United States, but the association between these changes and neonatal mortality remains unknown.

OBJECTIVE

To estimate changes in the gestational age distribution among spontaneous and clinician-initiated deliveries between 2006 and 2013 and associated changes in neonatal mortality.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort analysis was conducted of 22 million singleton live births without major malformations in the United States from 2006 to 2013. Data analysis was performed from August to October 2017.

MAIN OUTCOMES AND MEASURES

Changes in gestational age distribution among spontaneous and clinician-initiated deliveries at extremely preterm (20-27 weeks), very preterm (28-31 weeks), moderately preterm (32-33 weeks), late preterm (34-36 weeks), early term (37-38 weeks), term (39-40), late term (41 weeks), and postterm (42-44 weeks) gestations and changes in neonatal mortality rates at less than 28 days between 2006 and 2013. These changes were estimated from log-linear Poisson regression models with robust variance, adjusted for confounders.

RESULTS

Among 22 million births, 12 493 531 (56.7%) were spontaneous and 9 557 815 (43.3%) were clinician-initiated deliveries. Among spontaneous deliveries, the proportion of births at 20 to 27, 28 to 31, 32 to 33, 34 to 36, and 37 to 38 weeks declined. Among clinician-initiated deliveries, the proportion of births at 34 to 36 and 37 to 38 weeks declined and the proportion at 39 to 40 weeks increased. Among spontaneous deliveries, overall neonatal mortality rates declined from 1.8 to 1.3 per 1000 live births, mainly at 20 to 27 weeks (adjusted annual decline, 1%; 95% CI, -2% to -1%) and 28 to 31 weeks (adjusted annual decline, 6%; 95% CI, -8% to -5%). Among clinician-initiated deliveries, overall mortality rates remained unchanged (2.1 to 2.2 per 1000 live births). However, mortality rates declined (0.6 to 0.5 per 1000 live births) at 39 to 40 weeks by 1% (95% CI, -3% to -0.4%) annually, adjusted for confounders.

CONCLUSIONS AND RELEVANCE

In the United States, there was a decline in spontaneous deliveries associated with an overall decline in neonatal mortality. Although clinician-initiated deliveries increased at 39 to 40 weeks, neonatal mortality at that gestation declined.

Public Health Implications of Very Preterm Birth

With advanced perinatal care and technology, survival among infants born very preterm (<32 weeks gestation) has improved dramatically over the last several decades. However, adverse medical and neurodevelopmental outcomes for those born very preterm remains high, particularly at the lowest gestational ages. Public health plays a critical role in providing data to assess population-based risks associated with very preterm birth, addressing disparities, and identifying opportunities for prevention, including improving the health of reproductive-age women, before, during, and after pregnancy.

Association of Temporal Changes in Gestational Age With Perinatal Mortality in the United States, 2007-2015

Importance

Whether the changing gestational age distribution in the United States since 2005 has affected perinatal mortality remains unknown.

Objective

To examine changes in gestational age distribution and gestational age-specific perinatal mortality.

Design, Setting, and Participants

This retrospective cohort study examined trends in US perinatal mortality by linking live birth and infant death data among more than 35 million singleton births from January 1, 2007, through December 31, 2015.

Exposures

Year of birth and changes in gestational age distribution.

Main Outcomes and Measures

Changes in the proportion of births at gestational ages 20 to 27, 28 to 31, 32 to 33, 34 to 36, 37 to 38, 39 to 40, 41, and 42 to 44 weeks; changes in perinatal mortality (stillbirth at ≥20 weeks, and neonatal deaths at <28 days) rates; and contribution of gestational age changes to perinatal mortality. Trends were estimated from log-linear regression models adjusted for confounders.

Results

Among the 34 236 577 singleton live births during the study period, the proportion of births at all gestational ages declined, except at 39 to 40 weeks, which increased (54.5% in 2007 to 60.2% in 2015). Overall perinatal mortality declined from 9.0 to 8.6 per 1000 births (P < .001). Stillbirths declined from 5.7 to 5.6 per 1000 births (P < .001), and neonatal mortality declined from 3.3 to 3.0 per 1000 births (P < .001). Although the proportion of births at gestational ages 34 to 36, 37 to 38, and 42 to 44 weeks declined, perinatal mortality rates at these gestational ages showed annual adjusted relative increases of 1.0% (95% CI, 0.6%-1.4%), 2.3% (95% CI, 1.9%-2.8%), and 4.2% (95% CI, 1.5%-7.0%), respectively. Neonatal mortality rates at gestational ages 34 to 36 and 37 to 38 weeks showed a relative adjusted annual increase of 0.9% (95% CI, 0.2%-1.6%) and 3.1% (95% CI, 2.1%-4.1%), respectively. Although the proportion of births at gestational age 39 to 40 weeks increased, perinatal mortality showed an annual relative adjusted decline of -1.3% (95% CI, -1.8% to -0.9%). The decline in neonatal mortality rate was largely attributable to changes in the gestational age distribution than to gestational age-specific mortality.

Conclusions and Relevance

Although the proportion of births at gestational age 39 to 40 weeks increased, perinatal mortality at this gestational age declined. This finding may be owing to pregnancies delivered at 39 to 40 weeks that previously would have been unnecessarily delivered earlier, leaving fetuses at higher risk for mortality at other gestational ages.

Evaluation of a Multilevel Intervention to Reduce Preterm Birth Among Black Women in Newark, New Jersey: A Controlled Interrupted Time Series Analysis

Objective To evaluate the effectiveness of a multilevel intervention, Healthy Babies are Worth the Wait (HBWW), in reducing preterm birth (PTB) and very preterm birth (VPTB) among black women in Newark, NJ. Methods HBWW is a program linking the local March of Dimes office, providers, community-based organizations, and public health institutions to increase uptake of evidence based preterm birth interventions. We used birth certificate data before (2009-2011) and after (2012-2015) the introduction of HBWW in Newark. We estimated differences in PTB and VPTB between these periods among black women in Newark and compared them to rate differences among black women in the rest of NJ (difference-in-differences). We used interrupted time series analysis (ITSA) to examine declines in PTB and VPTB following the introduction of HBWW controlling for secular trends. All models adjusted for maternal age, education and parity. Results PTB declined in Newark 1.1 case per 100 (95% confidence interval (CI) - 2.3, 0) and in the rest of NJ 0.5 case per 100 (- 1.4, 0.4) (difference-in-differences = 0.6 fewer cases per 100 in Newark, 95% CI - 1.6, 0.3). VPTB declined in both Newark (- 0.6 cases per 100, 95% CI - 1.0, 0) and the rest of NJ (- 0.2 cases per 100, 95% CI - 0, 0.3) (difference-in-differences = 0.4 fewer cases per 100 in Newark, 95% CI - 0.9, 0). However, using ITSA the downward VPTB trend in Newark was not different from the rest of NJ or pre-intervention trends. Conclusions for Practice Our study supports the importance of critically evaluating and advancing complex interventions to reduce PTB among black women.

The Collaborative Improvement and Innovation Network (CoIIN) to Reduce Infant Mortality: An Outcome Evaluation From the US South, 2011 to 2014

OBJECTIVES

To evaluate the impact of the Southern Public Health Regions' (Regions IV and IV) Collaborative Improvement and Innovation Network (CoIIN) to Reduce Infant Mortality, supported by the US Health Resources and Services Administration.

METHODS

We examined pre-post change (2011-2014) for CoIIN strategies with available outcome data from vital records (early elective delivery, smoking) and the Pregnancy Risk Assessment Monitoring System (safe sleep) as well as preterm birth and infant mortality for Regions IV and VI relative to all other regions.

RESULTS

For most outcomes, CoIIN improvements were greater in Regions IV and VI than in other regions. For example, early elective delivery decreased by 22% versus 14% in other regions, smoking cessation during pregnancy increased by 7% versus 2%, and back sleep position increased by 5% versus 2%. Preterm birth decreased by 4%, twice that observed in other regions, but infant mortality reductions did not differ significantly.

CONCLUSIONS

The CoIIN approach to public health improvement shows promise in accelerating progress in intermediate outcomes and preterm birth. Impact on infant mortality may require additional strategies and sustained efforts.

Temporal trends of preterm birth in Shenzhen, China: a retrospective study

BACKGROUND

Preterm birth is the leading cause of child mortality under 5 years of age. Temporal trends in preterm birth rates are highly heterogeneous among countries and little information exists for China. To address this data gap, we investigated annual changes in preterm birth incidence rate and explored potential determinants of these changes in Shenzhen, China.

METHODS

A total of 1.4 million live births, during 2003-2012, were included from the Shenzhen birth registry. Negative-binominal regression models were used to estimate the annual percent changes in incidence. To identify the potential determinants behind temporal trends, we estimated the contribution of each changing risk factor to changes in rate by calculating the difference in population-attributable risk fraction.

RESULTS

Annual preterm birth incidence rates increased by 0.94% (95% CI 0.30%, 1.58%) overall, 3.60% (95% CI 2.73%, 4.48%) for medically induced, and 3.13% (95% CI 1.01%, 5.31%) for preterm premature rupture of membranes, but decreased by 2.34% (95% CI 1.62%, 3.06%) for spontaneous preterm labor. Higher maternal educational attainment (0.20 rate increase), lower proportion of inadequate prenatal care (0.15 rate reduction), more multipara (0.08 rate reduction), decreased proportion of preeclampsia or eclampsia (0.05 rate reduction), and larger proportion of young and older pregnant women (0.04 rate increase) were significant contributors to the overall change over time. Contributions of changing risk factors were different between preterm birth subtypes.

CONCLUSIONS

Preterm birth rate in Shenzhen, China increased overall during 2003-2012, although trends varied across three preterm birth subtypes. The rising rates were associated with changes in maternal education and age.

Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in singleton gestations with a short cervix: a meta-analysis of individual patient data

BACKGROUND

The efficacy of vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in singleton gestations with a short cervix has been questioned after publication of the OPPTIMUM study.

OBJECTIVE

To determine whether vaginal progesterone prevents preterm birth and improves perinatal outcomes in asymptomatic women with a singleton gestation and a midtrimester sonographic short cervix.

STUDY DESIGN

We searched MEDLINE, EMBASE, LILACS, and CINAHL (from their inception to September 2017); Cochrane databases; bibliographies; and conference proceedings for randomized controlled trials comparing vaginal progesterone vs placebo/no treatment in women with a singleton gestation and a midtrimester sonographic cervical length ≤25 mm. This was a systematic review and meta-analysis of individual patient data. The primary outcome was preterm birth <33 weeks of gestation. Secondary outcomes included adverse perinatal outcomes and neurodevelopmental and health outcomes at 2 years of age. Individual patient data were analyzed using a 2-stage approach. Pooled relative risks with 95% confidence intervals were calculated. Quality of evidence was assessed using the GRADE methodology.

RESULTS

Data were available from 974 women (498 allocated to vaginal progesterone, 476 allocated to placebo) with a cervical length ≤25 mm participating in 5 high-quality trials. Vaginal progesterone was associated with a significant reduction in the risk of preterm birth <33 weeks of gestation (relative risk, 0.62; 95% confidence interval, 0.47-0.81; P = .0006; high-quality evidence). Moreover, vaginal progesterone significantly decreased the risk of preterm birth <36, <35, <34, <32, <30, and <28 weeks of gestation; spontaneous preterm birth <33 and <34 weeks of gestation; respiratory distress syndrome; composite neonatal morbidity and mortality; birthweight <1500 and <2500 g; and admission to the neonatal intensive care unit (relative risks from 0.47-0.82; high-quality evidence for all). There were 7 (1.4%) neonatal deaths in the vaginal progesterone group and 15 (3.2%) in the placebo group (relative risk, 0.44; 95% confidence interval, 0.18-1.07; P = .07; low-quality evidence). Maternal adverse events, congenital anomalies, and adverse neurodevelopmental and health outcomes at 2 years of age did not differ between groups.

CONCLUSION

Vaginal progesterone decreases the risk of preterm birth and improves perinatal outcomes in singleton gestations with a midtrimester sonographic short cervix, without any demonstrable deleterious effects on childhood neurodevelopment.

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.

Assessment of cervical elastography strain pattern and its association with preterm birth

OBJECTIVE

The aim of the study was to assess the cervical strain pattern by an ultrasound elastography cervix examination and to determine its association with preterm delivery.

METHODS

In this study, 30 cases resulting in preterm birth and 30 gestational age-matched controls were included. A vaginal ultrasound examination with cervical length and elastography measurement was performed. We calculated four strain ratios (SR1-SR4) of the regions of interest (ROIs) arranged in pairs in four different positions on the anterior cervical lip. The strain ratios were correlated to the outcome of spontaneous preterm delivery. The inter-observer and intra-observer variability of the strain measurement was evaluated.

RESULTS

We observed an association between the value of the strain ratio that was calculated from the ROIs placed side by side in the middle of the anterior lip (SR4), and preterm delivery (P<0.001). The predictive values of cervical length and SR4 were comparable (AUC 0.7394; AUC 0.8322, respectively). The combination of cervical length and SR4 was superior in predicting preterm delivery compared to both parameters alone (AUC 0.8789). The inter-observer and intra-observer variability of data acquisition and measurement was excellent.

CONCLUSIONS

Our study assesses the cervical elastography strain pattern and shows a correlation to a spontaneous preterm birth.

The pathophysiology of human premature cervical remodeling resulting in spontaneous preterm birth: Where are we now?

Approximately one in ten (approximately 500,000) pregnancies results in preterm birth (PTB) annually in the United States. Although we have seen a slight decrease in the U.S. PTB rate between 2007 and 2014, data from 2014 to 2015 shows the preterm birth rate has slightly increased. It is even more intriguing to note that the rate of PTB has not significantly decreased since the 1980s. In order to decrease the rate of spontaneous preterm birth (sPTB), it is imperative that we improve our understanding of normal and abnormal reproductive tissue structure and function and how these tissues interact with each other at a cellular and biochemical level. Since other chapters in this issue will be focusing on the myometrium and fetal membranes, the goal of this chapter is to focus on the compartment of the cervix. We will review the current literature on normal and abnormal human cervical tissue remodeling and identify gaps in knowledge. Our goal is also to introduce a revised paradigm of normal cervical tissue structure and function which will provide novel research opportunities that may ultimately lead to developing safe and effective interventions to significantly decrease the rate and complications of prematurity.

US trends in abortion and preterm birth

BACKGROUND

A recent large meta-analysis concluded that prior surgical abortion was an independent risk factor for spontaneous preterm birth (PTB), while they found no significant correlation between PTB and medical abortion.

OBJECTIVE

To evaluate the potential impact of changes in US abortion rates and practices on US incidence of PTB rate.

STUDY DESIGN

This was an epidemiologic analysis of legal abortion and PTB data in the USA from 2003 to 2012. Birth data (annual total birth, annual number and incidence of PTB, defined as PTB <37 weeks) are from National Vital Statistics Reports from the National Center for Health Statistics, Center of Disease Control and Prevention (CDC). Abortion data were collected using Abortion Surveillance provided by the CDC. Abortion incidence was reported overall, and by type: surgical, medical method and procedures reported as "other" such as intrauterine instillation and hysterectomy/hysterotomy. To test for the trend of abortion and of PTB over time, we used the chi-squared test for trend. The primary outcome of our study was the correlation trend analysis between abortion rate and PTB rate. Pearson correlation test was used. A two-tailed p value of 0.05 or less was considered significant.

RESULTS

From 2003 to 2012 there were 41 206 315 births in USA, of which 5 042 982 (12.2%) were <37 weeks. The PTB rate declined significantly from 12.3% in 2003 to 11.5% in 2012 (p value test for trend <.04). Out of the 6 122 649 legal abortions, reported by type of procedure, performed from 2003 to 2012 in USA, 5 132 789 were surgical abortion (82.8%) and 860 288 (14.0%) were medical. Chi-squared test for trend showed that the rate of surgical abortion significantly decreased from 88.9 to 78.0% (p < .01) while the rate of medical abortion significantly increased from 7.9 to 21.9% (p < .01) from 2003 to 2012, respectively. The rate of PTB was correlated with the rate of medical abortion (p = .01) and of surgical abortion (p = .02) over time. The higher the surgical abortion rate, the higher the incidence of PTB (Pearson correlation 0.712); the higher the medical abortion rate, the lower the incidence of PTB (Pearson correlation -0.731).

CONCLUSION

Recent changes in abortion practices may be associated with the current decrease in US incidence of PTB. Further study on the effect of surgical versus medical abortion is warranted regarding a possible effect on the incidence of PTB.

Reducing preterm birth by a statewide multifaceted program: an implementation study

BACKGROUND

A comprehensive preterm birth prevention program was introduced in the state of Western Australia encompassing new clinical guidelines, an outreach program for health care practitioners, a public health program for women and their families based on print and social media, and a new clinic at the state's sole tertiary level perinatal center for referral of those pregnant women at highest risk. The initiative had the single aim of safely lowering the rate of preterm birth.

OBJECTIVE

The objective of the study was to evaluate the outcomes of the initiative on the rates of preterm birth both statewide and in the single tertiary level perinatal referral center.

STUDY DESIGN

This was a prospective population-based cohort study of perinatal outcomes before and after 1 full year of implementation of the preterm birth prevention program.

RESULTS

In the state overall, the rate of singleton preterm birth was reduced by 7.6% and was lower than in any of the preceding 6 years. This reduction amounted to 196 cases relative to the year before the introduction of the initiative and the effect extended from the 28-31 week gestational age group onward. Within the tertiary level center, the rate of preterm birth in 2015 was also significantly lower than in the preceding years.

CONCLUSION

A comprehensive and multifaceted preterm birth prevention program aimed at both health care practitioners and the general public, operating within the environment of a government-funded universal health care system can significantly lower the rate of early birth. Further research is now required to increase the effect and to determine the relative contributions of each of the interventions.

Effect of partial compliance on the prevention of recurrent preterm birth in women receiving weekly 17 alpha-hydroxyprogesterone caproate injections

PURPOSE

To analyze the effect of partial compliance on preterm birth (PTB) prevention among women with previous PTB and receiving 17 alpha-hydroxyprogesterone caproate (17-OHPC).

STUDY DESIGN

This is a secondary analysis of a multicenter trial for the prevention of recurrent PTB. Women with prior PTB were randomly assigned between 15 0/7 and 20 3/7 weeks to weekly injections of either 17-OHPC or placebo. Full 100% compliance (group 1) was compared to 40-80% (group 2). Recurrent PTB rates and odds ratios were calculated. Student's t, Chi-square, Wilcoxon Rank-Sum, multivariate logistic regression and Breslow-Day tests were used.

RESULTS

Group 1 included 370 women versus 35 in group 2. In each group, the PTB rate was significantly reduced in pregnancies receiving 17-OHPC compared to placebo. The adjusted odds ratio for PTB rate in group 1 was 0.48 (95% CI 0.31-0.75) versus 0.18 (95% CI 0.04-0.92) in group 2. Comparing the homogeneity of both odds ratios, the rates of recurrent PTB prevention in both groups were not statistically different (Breslow-Day test; p= .15).

CONCLUSION

A compliance rate of 40-80% did not significantly reduce 17-OHPC's efficacy. If confirmed, our findings could lead to a dramatic decrease in costs related to prevention of recurrent PTB.

Explaining the recent decrease in US infant mortality rate, 2007-2013

BACKGROUND

The US infant mortality rate has been steadily decreasing in recent years as has the preterm birth rate; preterm birth is a major factor associated with death during the first year of life. The degree to which changes in gestational age-specific mortality and changes in the distribution of births by gestational age have contributed to the decrease in the infant mortality rate requires clarification.

OBJECTIVE

The objective of the study was to better understand the major contributors to the 2007-2013 infant mortality decline for the total population and for infants born to non-Hispanic black, non-Hispanic white, and Hispanic women.

STUDY DESIGN

We identified births and infant deaths from 2007 and 2013 Centers for Disease Control and Prevention National Vital Statistics System's period linked birth and infant death files. We included all deaths and births for which there was a reported gestational age at birth on the birth certificate of 22 weeks or greater. The decrease in the infant mortality rate was disaggregated such that all of the change could be attributed to improvements in gestational age-specific infant mortality rates and changes in the distribution of gestational age, by week of gestation, using the Kitagawa method. Sensitivity analyses were performed to account for records in which the obstetric estimate of gestational age was missing and for deaths and births less than 22 weeks' gestation. Maternal race and ethnicity information was obtained from the birth certificate.

RESULTS

The infant mortality rates after exclusions were 5.72 and 4.92 per 1000 live births for 2007 and 2013, respectively, with an absolute difference of -0.80 (14% decrease). Infant mortality rates declined by 11% for non-Hispanic whites, by 19% for non-Hispanic blacks, and by 14% for Hispanics during the period. Compared with 2007, the proportion of births in each gestational age category was lower in 2013 with the exception of 39 weeks during which there was an increase in the proportion of births from 30.1% in 2007 to 37.5% in 2013. Gestational age-specific mortality decreased for each gestational age category between 2007 and 2013 except 33 weeks and >42 weeks. About 31% of the decrease in the US infant mortality rate from 2007 through 2013 was due to changes in the gestational age distribution, and 69% was due to improvements in gestational age-specific survival. Improvements in the gestational age distribution from 2007 through 2013 benefited infants of non-Hispanic white women (48%) the most, followed by infants of non-Hispanic black (31%) and Hispanic (14%) women.

CONCLUSION

Infant mortality improved between 2007 and 2013 as a result of both improvements in the distribution of gestational age at birth and improvements in survival after birth. The differential contribution of improvements in the gestational age distribution at birth by race and ethnicity suggests that preconception and antenatal health and health care aimed at preventing or delaying preterm birth may not be reaching all populations.

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.

The use of cervical sonography to differentiate true from false labor in term patients presenting for labor check

BACKGROUND

Cervical length by transvaginal ultrasound to predict preterm labor is widely used in clinical practice. Virtually no data exist on cervical length measurement to differentiate true from false labor in term patients who present for labor check. False-positive diagnosis of true labor at term may lead to unnecessary hospital admissions, obstetrical interventions, resource utilization, and cost.

OBJECTIVE

We sought to determine if cervical length by transvaginal ultrasound can differentiate true from false labor in term patients presenting for labor check.

STUDY DESIGN

This is a prospective observational study of women presenting to labor and delivery with labor symptoms at 37-42 weeks, singleton cephalic gestation, regular uterine contractions (≥4/20 min), intact membranes, and cervix ≤4 cm dilated and ≤80% effaced. Those patients with placenta previa and indications for immediate delivery were excluded. The shortest best cervical length of 3 collected images was used for analysis. Providers managing labor were blinded to the cervical length. True labor was defined as spontaneous rupture of membranes or spontaneous cervical dilation ≥4 cm and ≥80% effaced within 24 hours of cervical length measurement. In the absence of these outcomes, labor status was determined as false labor. Receiver operating characteristic curves were generated to assess the predictive ability of cervical length to differentiate true from false labor and were analyzed separately for primiparous and multiparous patients. The diagnostic accuracies of various cervical length cutoffs were determined. The relationship of cervical length and time to delivery was also analyzed including both use and nonuse of oxytocin.

RESULTS

In all, 77 patients were included in the study; the prevalence of true labor was 58.4% (45/77). Patients who were in true labor had shorter cervical length as compared to those in false labor: median 1.3 cm (range 0.5-4.1) vs 2.4 cm (range 1.0-5.0), respectively (P < .001). The area under the receiver operating characteristic curve for primiparous patients was 0.88 (P < .001) and for multiparous patients was 0.76 (P < .01), both demonstrating good correlation. The area under the receiver operating characteristic curves were not significantly different between primiparous and multiparous (P = .23). The area under the receiver operating characteristic curve for primiparous and multiparous patients combined was 0.8 (P < .0001), indicating a good overall correlation between cervical length and its ability to differentiate true from false labor. Overall, a cervical length cutoff of ≤1.5 cm to predict true labor had the highest specificity (81%), positive predictive value (83%), and positive likelihood ratio (4.2). There were no differences in cervical length prediction between primiparous and multiparous patients. Cervical length was positively correlated with time to delivery, regardless of the use of oxytocin.

CONCLUSION

In differentiating true from false labor in term patients who present for labor check, a cervical length of ≤1.5 cm was the most clinically optimal cutoff with the lowest false positive rate-due to its highest specificity-and highest positive predictive value and positive likelihood ratios. Its use to decide admission in patients at term with labor symptoms may prevent unnecessary admissions, obstetrical interventions, resource utilization, and cost.

Vaginal progesterone decreases preterm birth ≤ 34 weeks of gestation in women with a singleton pregnancy and a short cervix: an updated meta-analysis including data from the OPPTIMUM study

OBJECTIVE

To evaluate the efficacy of vaginal progesterone administration for preventing preterm birth and perinatal morbidity and mortality in asymptomatic women with a singleton gestation and a mid-trimester sonographic cervical length (CL) ≤ 25 mm.

METHODS

This was an updated systematic review and meta-analysis of randomized controlled trials comparing the use of vaginal progesterone to placebo/no treatment in women with a singleton gestation and a mid-trimester sonographic CL ≤ 25 mm. Electronic databases, from their inception to May 2016, bibliographies and conference proceedings were searched. The primary outcome measure was preterm birth ≤ 34 weeks of gestation or fetal death. Two reviewers independently selected studies, assessed the risk of bias and extracted the data. Pooled relative risks (RRs) with 95% confidence intervals (CI) were calculated.

RESULTS

Five trials involving 974 women were included. A meta-analysis, including data from the OPPTIMUM study, showed that vaginal progesterone significantly decreased the risk of preterm birth ≤ 34 weeks of gestation or fetal death compared to placebo (18.1% vs 27.5%; RR, 0.66 (95% CI, 0.52-0.83); P = 0.0005; five studies; 974 women). Meta-analyses of data from four trials (723 women) showed that vaginal progesterone administration was associated with a statistically significant reduction in the risk of preterm birth occurring at < 28 to < 36 gestational weeks (RRs from 0.51 to 0.79), respiratory distress syndrome (RR, 0.47 (95% CI, 0.27-0.81)), composite neonatal morbidity and mortality (RR, 0.59 (95% CI, 0.38-0.91)), birth weight < 1500 g (RR, 0.52 (95% CI, 0.34-0.81)) and admission to the neonatal intensive care unit (RR, 0.67 (95% CI, 0.50-0.91)). There were no significant differences in neurodevelopmental outcomes at 2 years of age between the vaginal progesterone and placebo groups.

CONCLUSION

This updated systematic review and meta-analysis reaffirms that vaginal progesterone reduces the risk of preterm birth and neonatal morbidity and mortality in women with a singleton gestation and a mid-trimester CL ≤ 25 mm, without any deleterious effects on neurodevelopmental outcome. Clinicians should continue to perform universal transvaginal CL screening at 18-24 weeks of gestation in women with a singleton gestation and to offer vaginal progesterone to those with a CL ≤ 25 mm. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Temporal Trends in Late Preterm and Early Term Birth Rates in 6 High-Income Countries in North America and Europe and Association With Clinician-Initiated Obstetric Interventions

IMPORTANCE

Clinicians have been urged to delay the use of obstetric interventions (eg, labor induction, cesarean delivery) until 39 weeks or later in the absence of maternal or fetal indications for intervention.

OBJECTIVE

To describe recent trends in late preterm and early term birth rates in 6 high-income countries and assess association with use of clinician-initiated obstetric interventions.

DESIGN

Retrospective analysis of singleton live births from 2006 to the latest available year (ranging from 2010 to 2015) in Canada, Denmark, Finland, Norway, Sweden, and the United States.

EXPOSURES

Use of clinician-initiated obstetric intervention (either labor induction or prelabor cesarean delivery) during delivery.

MAIN OUTCOMES AND MEASURES

Annual country-specific late preterm (34-36 weeks) and early term (37-38 weeks) birth rates.

RESULTS

The study population included 2,415,432 Canadian births in 2006-2014 (4.8% late preterm; 25.3% early term); 305,947 Danish births in 2006-2010 (3.6% late preterm; 18.8% early term); 571,937 Finnish births in 2006-2015 (3.3% late preterm; 16.8% early term); 468,954 Norwegian births in 2006-2013 (3.8% late preterm; 17.2% early term); 737,754 Swedish births in 2006-2012 (3.6% late preterm; 18.7% early term); and 25,788,558 US births in 2006-2014 (6.0% late preterm; 26.9% early term). Late preterm birth rates decreased in Norway (3.9% to 3.5%) and the United States (6.8% to 5.7%). Early term birth rates decreased in Norway (17.6% to 16.8%), Sweden (19.4% to 18.5%), and the United States (30.2% to 24.4%). In the United States, early term birth rates decreased from 33.0% in 2006 to 21.1% in 2014 among births with clinician-initiated obstetric intervention, and from 29.7% in 2006 to 27.1% in 2014 among births without clinician-initiated obstetric intervention. Rates of clinician-initiated obstetric intervention increased among late preterm births in Canada (28.0% to 37.9%), Denmark (22.2% to 25.0%), and Finland (25.1% to 38.5%), and among early term births in Denmark (38.4% to 43.8%) and Finland (29.8% to 40.1%).

CONCLUSIONS AND RELEVANCE

Between 2006 and 2014, late preterm and early term birth rates decreased in the United States, and an association was observed between early term birth rates and decreasing clinician-initiated obstetric interventions. Late preterm births also decreased in Norway, and early term births decreased in Norway and Sweden. Clinician-initiated obstetric interventions increased in some countries but no association was found with rates of late preterm or early term birth.

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.