Trends in Spontaneous and Indicated Preterm Delivery Among Singleton Gestations in the United States, 2005–2012

Asymptomatic short cervix and threatened preterm labor: A comparative study on perinatal outcomes

OBJECTIVE

To determine the rate of delivery within 15 days of admission among patients with an asymptomatic short cervix (ASC) compared to those admitted for threatened preterm labor (TPL).

MATERIAL AND METHODS

This retrospective study conducted in a tertiary maternity hospital, included patients with a singleton pregnancy admitted with a cervical length of less than 25 mm between 24 and 34 weeks. The population was divided into two groups, patients with ASC (i.e., with no contractions at admission) and patients with TPL. The primary outcome was the delivery rate within 15 days of admission. Secondary outcomes included gestational age at delivery, preterm delivery rate before 37°/7 weeks and before 34°/7 weeks, admission to delivery interval, 5 min Apgar score and transfer to neonatal intensive care unit rate. The characteristics of the two groups and the primary and secondary outcomes were compared between the two groups using univariate analysis. Two subgroup analysis were performed, one restricted to patients with a mildly modified CL (15 ≤ CL < 25 mm), and one excluding patients at high risk of preterm birth.

RESULTS

Among the 247 included patients, 136 (55.1 %) had TPL, and 111 (44.9 %) ASC. There were no significant differences in the rate of patient who delivered within 15 days of admission between the groups, 13.2 % in the TPL group vs 8.0 % in the ASC group (p = 0.22). Patients in the TPL group had a significantly higher frequency of delivery before 34 weeks compared to those in the ASC group (19.9 % versus 9.0 %, p = 0.02 This finding persisted in the subgroup analysis excluding patients at high risk of preterm birth (16.5 % in the TPL subgroup vs. 6.9 % in the ASC subgroup, p = 0.04). There were no significant differences in the rates of preterm delivery before 37 weeks, the admission-to-delivery interval, or neonatal outcomes between the two groups or within the subgroup analyses.

CONCLUSION

The frequency of delivery within 15 days of admission was not statistically different between patients with an asymptomatic short cervix and those with TPL. Nevertheless, these asymptomatic patients delivered significantly later and less frequently before 34 weeks, with only one in ten requiring corticosteroids.

Assessing the multifaceted cervix: examining cervical gland area at cervical length screening to predict spontaneous preterm birth

BACKGROUND

Biologically active cervical glands provide a mucous barrier while influencing the composition and biomechanical strength of the cervical extracellular matrix. Cervical remodeling during ripening may be reflected as loss of the sonographic cervical gland area. As sonographic cervical length remains suboptimal for universal screening, adjunctive evaluation of other facets of the mid-trimester cervix may impart additional screening benefit.

OBJECTIVE

To sonographically assess the cervical gland area at universal cervical length screening for preterm birth.

STUDY DESIGN

We performed a retrospective cohort study of singletons with transvaginal cervical length screening universally performed during anatomic survey between 18 0/7 and 23 6/7 weeks and subsequent live delivery at a single institution in 2018. Uterine anomalies, cerclage, suboptimal imaging, or medically indicated preterm birth were excluded. Ultrasound images were assessed for cervical length and cervical gland area (with quantitative measurements when present). The primary outcome was spontaneous preterm birth <37 weeks. Absent and present gland groups were compared using χ2, Fisher's exact, T-test, and multivariate logistic regression (adjusting for parity and progesterone use, as well as the gestational age, cervical length, and gland absence at screening ultrasound). Gland measurements were evaluated using the Mann-Whitney-U Test and Spearman's correlation.

RESULTS

Among the cohort of 772 patients, absent and present CGA groups were overall similar. Patients were on average 33 years old, ∼20 weeks gestation at screening ultrasound, and overall, 2.5% had history of prior spontaneous preterm birth. The absent gland group was more likely to have been taking progesterone (17% vs 4%, P=.04). Overall rate of preterm birth was 2.6%. However, the 2.3% of patients with absent cervical gland area were significantly more likely to deliver <37 weeks (aOR 23.9, 95% CI 6.4-89, P<.001). Multivariate logistic regression demonstrated better performance of a cervical length screening model for preterm birth prediction with the addition of qualitative gland evaluation (P<.001). Qualitative gland assessment was reproducible (PABAK 0.89), but quantitative gland measurements did not correlate with preterm birth.

CONCLUSION

Qualitative gland absence at mid-gestation cervical length screening was associated with subsequent spontaneous preterm birth, whereas quantitative gland measurements were not. Multifaceted ultrasound screening may be needed to adequately evaluate the multiple biologic functions of the cervix.

Neighborhood mobility and racial disparities in preterm birth: A sibling study in California

Recent work finds that upward neighborhood mobility-defined as reductions in neighborhood socioeconomic disadvantage due to moving-may improve birth outcomes. Less work, however, explores whether changes in socioeconomic context differentially impact birth outcomes by maternal race and ethnicity. In the US, mothers of minoritized racial and ethnic identity often experience worse neighborhood conditions and pregnancy outcomes than White mothers. Using a sibling-linked dataset, we examined whether neighborhood mobility corresponds with changes in preterm birth risk among Asian (N = 130,079), Black (N = 50,149), Hispanic (N = 429,938), and White (N = 233,428) mothers who delivered multiple live births in California between 2005 and 2015. We linked residential addresses at each birth to census-derived indices of neighborhood disadvantage and defined levels of neighborhood mobility as moving-induced changes in disadvantage between pregnancies. We mapped neighborhood mobility patterns and fit conditional logistic regression models estimating the odds of preterm birth in the sibling delivered after moving, controlling for the risk of preterm birth in the sibling delivered before moving, by maternal race and ethnicity. Dot density maps highlight racialized patterns of neighborhood mobility and segregation between Black and White mothers. Regression results show that Black and, in some cases, Asian and Hispanic mothers who experienced upward mobility (moves away from neighborhood disadvantage) exhibited reduced odds of preterm birth in the second delivery. Upward mobility did not reduce the odds of preterm birth among White mothers. Findings suggest that policies and programs that enable opportunities for neighborhood mobility may reduce persistent racial and ethnic disparities in adverse birth outcomes.

Antenatal Late Preterm Steroids: The Evolution of the ALPS Trial

The Antenatal Late Preterm Steroids (ALPS) trial was designed to address respiratory morbidity common in infants born late preterm. The study was published in April, 2016 and, shortly thereafter, changed clinical practice in obstetrics in the United States. The following chapter describes the ALPS trial study design in detail, including the background leading to the trial, the study outcomes, and the initial findings of the long-term follow-up study. The ALPS story would not be complete without Elizabeth Thom, PhD, who died before her time. Her brilliance largely contributed to the design of the ALPS trial.

A multisite study to develop and validate first trimester, circulating microparticle biomarkers for tiered risk stratification of spontaneous preterm birth in nulliparas

BACKGROUND

Despite much research, advances in early prediction of spontaneous preterm birth (sPTB) has been slow. The evolving field of circulating microparticle (CMP) biology may identify novel blood-based, and clinically useful, biomarkers.

OBJECTIVE

To test the ability of a previously identified, 7-marker set of CMP-derived proteins from the first trimester of pregnancy, in the form of an in vitro diagnostic multivariate index assay (IVDMIA), to stratify pregnant patients according to their risk for sPTB.

STUDY DESIGN

We employed a previously validated set of CMP protein biomarkers, utilizing mass spectrometry assays and a nested case-control design in a subset of participants from the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be (nuMoM2b). We evaluated these biomarkers in the form of an IVDMIA to predict risk for sPTB at different gestational ages. Plasma samples collected at 9- to 13-weeks' gestation were analyzed. The IVDMIA assigned subjects to 1 of 3 sPTB risk categories: low risk (LR), moderate risk (MR), or high risk (HR). Independent validation on a set-aside set confirmed the IVDMIA's performance in risk stratification.

RESULTS

Samples from 400 participants from the nuMoM2b cohort were used for the study; of these, 160 delivered<37 weeks and 240 delivered at term. Through Monte Carlo simulation in which the validation results were adjusted based on actual weekly sPTB incidence rates in the nuMoM2b cohort, the IVDMIA stratifications demonstrated statistically significant differences among the risk groups in time-to-event (birth) analysis (P<.0001). The incidence-rate adjusted cumulative risks of sPTB at ≤32 weeks' gestation were 0.4%, 1.6%, and 7.5%, respectively for the LR, MR, and HR groups, respectively. Compared to the LR group, the corresponding risk ratios of the IVDMIA assigned MR and HR group were 4.25 (95% confidence interval [CI] 2.2-7.9) and 19.92 (95% CI 10.4-37.4), respectively.

CONCLUSION

A first trimester CMP protein biomarker panel can be used to stratify risk for sPTB at different gestational ages. Such a multitiered stratification tool could be used to assess risk early in pregnancy to enable timely clinical management and interventions, and, ultimately, to enable the development of tailored care pathways for sPTB prevention.

Placenta: an old organ with new functions

The transition from oviparity to viviparity and the establishment of feto-maternal communications introduced the placenta as the major anatomical site to provide nutrients, gases, and hormones to the developing fetus. The placenta has endocrine functions, orchestrates maternal adaptations to pregnancy at different periods of pregnancy, and acts as a selective barrier to minimize exposure of developing fetus to xenobiotics, pathogens, and parasites. Despite the fact that this ancient organ is central for establishment of a normal pregnancy in eutherians, the placenta remains one of the least studied organs. The first step of pregnancy, embryo implantation, is finely regulated by the trophoectoderm, the precursor of all trophoblast cells. There is a bidirectional communication between placenta and endometrium leading to decidualization, a critical step for maintenance of pregnancy. There are three-direction interactions between the placenta, maternal immune cells, and the endometrium for adaptation of endometrial immune system to the allogeneic fetus. While 65% of all systemically expressed human proteins have been found in the placenta tissues, it expresses numerous placenta-specific proteins, whose expression are dramatically changed in gestational diseases and could serve as biomarkers for early detection of gestational diseases. Surprisingly, placentation and carcinogenesis exhibit numerous shared features in metabolism and cell behavior, proteins and molecular signatures, signaling pathways, and tissue microenvironment, which proposes the concept of "cancer as ectopic trophoblastic cells". By extensive researches in this novel field, a handful of cancer biomarkers has been discovered. This review paper, which has been inspired in part by our extensive experiences during the past couple of years, highlights new aspects of placental functions with emphasis on its immunomodulatory role in establishment of a successful pregnancy and on a potential link between placentation and carcinogenesis.

The association between unintended hysterotomy extensions with cesarean delivery and subsequent preterm birth

BACKGROUND

An increased risk for preterm birth has been observed among individuals with a previous second stage cesarean delivery when compared with those with a previous vaginal delivery. One mechanism that may contribute to the increased risk for preterm birth following a second stage cesarean delivery is the increased risk for cervical injury because of extension of the uterine incision (hysterotomy) into the cervix. The contribution of hysterotomy extension to the rate of preterm birth in a subsequent pregnancy has not been investigated and may shed light on the mechanism underlying the observed relationship between the mode of delivery and subsequent preterm birth.

OBJECTIVE

We aimed to quantify the association between unintended hysterotomy extension and preterm birth in a subsequent delivery.

STUDY DESIGN

We performed a retrospective cohort study using electronic perinatal data collected from 2 university-affiliated obstetrical centers. The study included patients with a primary cesarean delivery of a term, singleton live birth and a subsequent singleton birth in the same catchment (2005-2021). The primary outcome was subsequent preterm birth <37 weeks' gestation; secondary outcomes included subsequent preterm birth at <34, <32, and <28 weeks' gestation. We assessed crude and adjusted associations between unintended hysterotomy extensions and subsequent preterm birth with log binomial regression models using rate ratios and 95% confidence intervals. Adjusted models included several characteristics of the primary cesarean delivery such as maternal age, length of active labor, indication for cesarean delivery, chorioamnionitis, and maternal comorbidity.

RESULTS

A total 4797 patients met the study inclusion criteria. The overall rate of unintended hysterotomy extension in the primary cesarean delivery was 6.0% and the total rate of preterm birth in the subsequent pregnancy was 4.8%. Patients with an unintended hysterotomy extension were more likely to have a longer duration of active labor, chorioamnionitis, failed vacuum delivery attempt, second stage cesarean delivery, and persistent occiput posterior position of the fetal head in the primary cesarean delivery and higher rates of smoking in the subsequent pregnancy. Multivariable analyses that controlled for several confounders showed that a history of hysterotomy extension was not associated with a higher risk for preterm birth <37 weeks' gestation (adjusted rate ratio, 1.55; 95% confidence interval, 0.98-2.47), but it was associated with preterm birth <34 weeks' gestation (adjusted rate ratio, 2.49; 95% confidence interval, 1.06-5.42).

CONCLUSION

Patients with a uterine incision extension have a 2.5 times higher rate of preterm birth <34 weeks' gestation when compared with patients who did not have this injury. This association was not observed for preterm birth <37 weeks' gestation. Future research should aim to replicate our analyses with incorporation of additional data to minimize the potential for residual confounding.

Trends in preterm birth in the Netherlands in 2011-2019: A population-based study among singletons and multiples

INTRODUCTION

Preterm birth (PTB) is the leading cause of infant mortality and morbidity worldwide. Rates of PTB in the Netherlands are declining, possibly due to the implementation of preventive strategies. In this study we assessed the overall trend in PTB rates in the Netherlands in recent years, and in more detail in specific subgroups to investigate potential groups that require scrutiny in the near future.

MATERIAL AND METHODS

Based on the national perinatal registry, we included all pregnancies without severe congenital abnormalities resulting in a birth from 24 to 42 completed weeks of gestation between 2011 and 2019 in the Netherlands. We assessed PTB rates in two different clinical subtypes (spontaneous vs. iatrogenic) and in five gestational age subgroups: 24-27+6 weeks (extreme), 28-31+6 weeks (very), 32-33+6 weeks (moderate, 34-36+6 weeks [late] and, in general, 24-36+6 weeks [overall PTB]). Trend analysis was performed using the Cochran Armitage test. We also compared PTB rates in different subgroups in the first 2 years compared to the last 2 years. Singleton and multiple gestations were analyzed separately.

RESULTS

We included 1 447 689 singleton and 23 250 multiple pregnancies in our study. In singletons, we observed a significant decline in PTB from 5.5% to 5.0% (p < 0.0001), mainly due to a decrease in iatrogenic PTBs. When focusing on different gestational age subgroups, there was a decrease in all iatrogenic PTB and in moderate to late spontaneous PTB. However, in spontaneous extreme and very PTB there was an significant increase. When assessing overall PTB risk in different subgroups, the decline was only visible in women with age ≥25 years, nulliparous and primiparous women, women with a medium or high socioeconomic status and hypertensive women. In multiples, the rate of PTB remained fairly stable, from 52.3% in 2011 to 54.1% in 2019 (p = 0.57).

CONCLUSIONS

In the Netherlands, between 2011 and 2019, PTB decreased, mainly due to a reduction in late PTB, and more in iatrogenic than in spontaneous PTB. Focus for the near future should be on specific subgroups in which the decline was not visible, such as women with a low socioeconomic status or a young age.

Spatial Patterning of Spontaneous and Medically Indicated Preterm Birth in Philadelphia

Preterm birth (PTB) remains a key public health issue that disproportionately affects Black individuals. Since spontaneous PTB (sPTB) and medically indicated PTB (mPTB) may have different causes and interventions, we quantified racial disparities for sPTB and mPTB, and we characterized the geographic patterning of these phenotypes, overall and according to race/ethnicity. We examined a pregnancy cohort of 83,952 singleton births at 2 Philadelphia hospitals from 2008-2020, and classified each PTB as sPTB or mPTB. We used binomial regression to quantify the magnitude of racial disparities between non-Hispanic Black and non-Hispanic White individuals, then generated small area estimates by applying a Bayesian model that accounts for small numbers and smooths estimates of PTB risk by borrowing information from neighboring areas. Racial disparities in both sPTB and mPTB were significant (relative risk of sPTB = 1.83, 95% confidence interval: 1.70, 1.98; relative risk of mPTB = 2.20, 95% confidence interval: 2.00, 2.42). The disparity was 20% greater in mPTB than sPTB. There was substantial geographic variation in PTB, sPTB, and mPTB risks and racial disparity. Our findings underscore the importance of distinguishing PTB phenotypes within the context of public health and preventive medicine. Future work should consider social and environmental exposures that may explain geographic differences in PTB risk and disparities.

Integrative analysis of noncoding mutations identifies the druggable genome in preterm birth

Preterm birth affects ~10% of pregnancies in the US. Despite familial associations, identifying at-risk genetic loci has been challenging. We built deep learning and graphical models to score mutational effects at base resolution via integrating the pregnant myometrial epigenome and large-scale patient genomes with spontaneous preterm birth (sPTB) from European and African American cohorts. We uncovered previously unidentified sPTB genes that are involved in myometrial muscle relaxation and inflammatory responses and that are regulated by the progesterone receptor near labor onset. We studied genomic variants in these genes in our recruited pregnant women administered progestin prophylaxis. We observed that mutation burden in these genes was predictive of responses to progestin treatment for preterm birth. To advance therapeutic development, we screened ~4000 compounds, identified candidate molecules that affect our identified genes, and experimentally validated their therapeutic effects on regulating labor. Together, our integrative approach revealed the druggable genome in preterm birth and provided a generalizable framework for studying complex diseases.

Experience of early-life pain in premature infants is associated with atypical cerebellar development and later neurodevelopmental deficits

BACKGROUND

Infants born very and extremely premature (V/EPT) are at a significantly elevated risk for neurodevelopmental disorders and delays even in the absence of structural brain injuries. These risks may be due to earlier-than-typical exposure to the extrauterine environment, and its bright lights, loud noises, and exposures to painful procedures. Given the relative underdeveloped pain modulatory responses in these infants, frequent pain exposures may confer risk for later deficits.

METHODS

Resting-state fMRI scans were collected at term equivalent age from 148 (45% male) infants born V/EPT and 99 infants (56% male) born at term age. Functional connectivity analyses were performed between functional regions correlating connectivity to the number of painful skin break procedures in the NICU, including heel lances, venipunctures, and IV placements. Subsequently, preterm infants returned at 18 months, for neurodevelopmental follow-up and completed assessments for autism risk and general neurodevelopment.

RESULTS

We observed that V/EPT infants exhibit pronounced hyperconnectivity within the cerebellum and between the cerebellum and both limbic and paralimbic regions correlating with the number of skin break procedures. Moreover, skin breaks were strongly associated with autism risk, motor, and language scores at 18 months. Subsample analyses revealed that the same cerebellar connections strongly correlating with breaks at term age were associated with language dysfunction at 18 months.

CONCLUSIONS

These results have significant implications for the clinical care of preterm infants undergoing painful exposures during routine NICU care, which typically occurs without anesthesia. Repeated pain exposures appear to have an increasingly detrimental effect on brain development during a critical period, and effects continue to be seen even 18 months later.

Validation of parental recall questionnaire to classify preterm delivery subtypes: Spontaneous preterm labour, preterm premature rupture of membranes and clinician-initiated preterm delivery

BACKGROUND

Preterm delivery (PTD) includes three main presenting subtypes: spontaneous preterm labour (sPTL), preterm premature rupture of membranes (pPROM) and clinician-initiated preterm delivery (ciPTD). PTD subtype data are rarely available from birth registries and are onerous to derive from medical records.

OBJECTIVES

To develop and test the validity of a questionnaire to classify PTD subtype based on birthing parent recall of labour and delivery events.

METHODS

The questionnaire was sent in 2022 to 581 patients with PTD history documented in the LIFECODES study, a hospital-based birth cohort in Boston, Massachusetts. Eighty-two respondents reported 94 PTDs that could be linked to medical records. Data on PTD subtype were extracted from medical records as the reference standard.

RESULTS

Medical records indicated 47 spontaneous (24 sPTL, 23 pPROM) and 47 ciPTD deliveries occurring a median eight years earlier. The sensitivity and specificity of the recall questionnaire were 88% (95% confidence interval: 68, 97%) and 89% (79, 95%) for sPTL; 96% (78, 100%) and 94% (86, 98%) for pPROM; and 83% (69, 92%) and 100% (92, 100%) for ciPTD, respectively. Greater time since pregnancy did not degrade the sensitivity or specificity of the parental recall questionnaire.

CONCLUSIONS

Although derived from a modest sample, the moderate-to-high sensitivity and specificity of the parental recall questionnaire to classify sPTL, pPROM and ciPTD demonstrates its potential for large studies of PTD and for correction of misclassification bias. Future studies are required to test the questionnaire in a variety of populations.

Impact of maternal obesity on preterm delivery in patients with cervical cerclage

BACKGROUND

Maternal obesity has risen in the United States in recent decades.

OBJECTIVE

This study aimed to evaluate the impact of maternal obesity on the risk for spontaneous preterm delivery and the risk for overall preterm delivery among patients with cervical cerclage placement.

STUDY DESIGN

This was a retrospective study in which data from the California Office of Statewide Health Planning and Development linked birth file from 2007 to 2012 were used, yielding a total of 3654 patients with and 2,804,671 patients without cervical cerclage placement. Exclusion criteria included patients with missing information on body mass index, multiple gestation, anomalous pregnancies, and gestations <20 weeks or >42 weeks. Patients in each group were identified and were further categorized based on body mass index with the nonobese group defined as having a body mass index of <30 kg/m², the obese group defined as having a body mass index of 30 to 40 kg/m², and the morbidly obese group defined as having a body mass index >40 kg/m². The risks for overall and spontaneous preterm delivery were compared between patients without obesity and those with obesity or those with morbid obesity patients. The analysis was stratified by cerclage placement.

RESULTS

Among patients who underwent cerclage placement, the risk for spontaneous preterm delivery was not significantly different in the obese and morbidly obese group when compared with the nonobese group (24.2% vs 20.6%; adjusted odds ratio, 1.18; 95% confidence interval, 0.97-1.43; and 24.5% vs 20.6%; adjusted odds ratio, 1.12; 0.78-1.62, respectively). However, among patients without cerclage placement, the obese and morbidly obese groups had a higher risk for spontaneous preterm delivery than the nonobese group (5.1% vs 4.4%; adjusted odds ratio, 1.04; 1.02-1.05; and 5.9% vs 4.4%; adjusted odds ratio, 1.03; 1.00-1.07, respectively). The risks for overall preterm delivery at <37 weeks' gestation were higher for the obese and morbidly obese groups than for the nonobese group among patients with cerclage (33.7% vs 28.2%; adjusted odds ratio, 1.23; 1.03-1.46; and 32.1% vs 28.2%; adjusted odds ratio, 1.01; 0.72-1.43, respectively). Similarly, among patients without cerclage placement, the risks for preterm delivery at <37 weeks' gestation were higher for the obese and morbidly obese groups than for the nonobese group (7.9% vs 6.8%; adjusted odds ratio, 1.05; 1.04-1.06; and 9.3% vs 6.8%; adjusted odds ratio, 1.10; 1.08-1.13, respectively).

CONCLUSION

Among patients who received a cervical cerclage for the prevention of preterm birth, obesity was not associated with an increased risk for spontaneous preterm delivery. However, it was associated with an overall increased risk for preterm delivery.

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..

Latency Period after Preterm Premature Rupture of Membranes: Singletons versus Twins

OBJECTIVE

Several studies have evaluated the differences in duration of latency and clinical outcomes between singleton and twin pregnancies after preterm premature rupture of membranes (PPROM); however, these data are limited to single-institution analyses and based on small sample sizes. The aim of this study was to assess differences in latency and clinical outcomes in singletons versus twin gestations affected by PPROM in a large, diverse cohort of women.

STUDY DESIGN

This is a secondary analysis of a multicenter trial of magnesium for neuroprotection in women at high risk of preterm birth. Our study included women with PPROM ≥ 24 weeks with singleton and twin gestations. We compared singleton versus twin gestation and our primary outcome was duration of latency after PPROM. Secondary outcomes included selected perinatal and neonatal outcomes including long-term neurodevelopmental outcomes. We fit a linear regression model to assess independent risk factors for latency duration.

RESULTS

Our study included 1,753 women, 1,602 singleton gestations (91%) and 151 twin gestations (9%). The median latency period was significantly shorter in twins (4 [interquartile range, IQR: 1-10] vs. 7 [IQR: 3-16] days, p < 0.001) and gestational age at delivery was significantly earlier (29.3 vs. 30.1 weeks, p = 0.001). Twins were more likely to develop neonatal sepsis (20.1 vs. 13.4%, p = 0.004), but rates of chorioamnionitis and abruption did not differ. Twins were more likely to suffer from adverse short-term neonatal outcomes, had higher rates of neonatal demise (7.9 vs. 3.8%, p = 0.002), and had higher rates of cerebral palsy (7.3 vs. 3.7, p = 0.005). When adjusting for confounders, twin gestation remained an independent risk factor for shorter latency (p < 0.001).

CONCLUSION

Twin gestations affected by PPROM had shorter latency, earlier delivery, and higher rates of short- and long-term morbidity. Despite having longer latency, singleton gestations did not have higher rates of complications associated with expectant management.

KEY POINTS

· Twins affected by PPROM had shorter latency duration and earlier gestational at delivery.. · Twins with PPROM had higher rates of both short- and long-term perinatal morbidity.. · Rates of chorioamnionitis and abruption did not differ between twins and singletons with PPROM..

Examining recent trends in spontaneous and iatrogenic preterm birth across race and ethnicity in a large managed care population

BACKGROUND

For the past several decades, epidemiological studies originating from the United States have consistently reported increasing rates of preterm birth (PTB). Despite the implementation of several clinical and public health interventions to reduce PTB rates, it remains the leading cause of infant morbidity and mortality in the United States and around the world.

OBJECTIVE

This study aimed to examine recent trends in preterm birth and its clinical subtypes by maternal race and ethnicity among singleton births.

STUDY DESIGN

Kaiser Permanente Southern California electronic health records for all singleton births between 2009 and 2020 (n=427,698) were used to examine preterm birth trends and their subtypes (spontaneous and iatrogenic preterm births). Data on preterm labor triage extracted from electronic health records using natural language processing were used to define preterm birth subtypes. Maternal race and ethnicity are categorized as non-Hispanic White, non-Hispanic Black, Hispanic, and non-Hispanic Asian or Pacific Islander. Multiple logistic regression was used to quantify the linear trend for preterm birth and its subtypes. Racial and ethnic trends were further examined by considering statistical interactions and stratifications.

RESULTS

From 2009 to 2020, the overall preterm birth rate decreased by 9.12% (from 8.04% to 7.31%; P<.001). The rates decreased by 19.29% among non-Hispanic Whites (from 7.23% to 5.83%; P<.001), 6.15% among Hispanics (from 7.82% to 7.34%; P=.036), and 12.60% among non-Hispanic Asian or Pacific Islanders (from 8.90% to 7.78%; P<.001), whereas a nonsignificantly increased preterm birth rate (8.45%) was observed among non-Hispanic Blacks (from 9.91% to 10.75%; P=.103). Between 2009 and 2020, overall spontaneous preterm birth rates decreased by 28.85% (from 5.75% to 4.09%; P<.001). However, overall iatrogenic preterm birth rates increased by 40.45% (from 2.29% to 3.22%; p<.001). Spontaneous preterm birth rates decreased by 34.73% among non-Hispanic Whites (from 5.44% to 3.55%; P<.001), 19.75% among non-Hispanic Blacks (from 6.82% to 5.47%; P<.001), 22.96% among Hispanics (from 5.55% to 4.28%; P<.001), and 28.19% among non-Hispanic Asian or Pacific Islanders (from 6.50% to 4.67%; P<.001). Iatrogenic preterm birth rates increased by 52.42% among non-Hispanic Whites (from 1.88% to 2.61%; P<.001), 107.89% among non-Hispanic Blacks (from 3.18% to 6.13%; P<.001), 46.88% among Hispanics (from 2.29% to 3.26%; P<.001), and 42.21% among non-Hispanic Asian or Pacific Islanders (from 2.45% to 3.44%; P<.001).

CONCLUSION

The overall preterm birth rate decreased over time and was driven by a decrease in the spontaneous preterm birth rate. There is racial and ethnic variability in the rates of spontaneous preterm birth and iatrogenic preterm birth. The observed increase in iatrogenic preterm birth among all racial and ethnic groups, especially non-Hispanic Blacks, is disconcerting and needs further investigation.

Optimal annual body mass index change for preventing spontaneous preterm birth in a subsequent pregnancy

Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality. Although PTB is known to recur, interpregnancy preventive strategies for PTB have not been established to date. Annual BMI change can serve as a specific target value for preventing obstetric complications during interpregnancy care/counseling. This value can also account for age-related weight gain (0.2 kg/m²/year). In a multicenter retrospective study, we investigated the optimal annual BMI change for preventing PTB recurrence using the data of individuals who had two singleton births from 2009 to 2019. The association between annual BMI change and spontaneous PTB (sPTB) was analyzed by separating cases of medically indicated PTB (mPTB) from those of sPTB. Previous history of sPTB was strongly associated with sPTB in the subsequent pregnancy (adjusted odds ratio [aOR], 12.7; 95% confidence interval [CI], 6.5-24.8). Increase in annual BMI was negatively associated with sPTB (aOR, 0.6; 95% CI 0.5-0.9). The sPTB recurrence rate was significantly lower in patients with an annual BMI change of ≥ 0.25 kg/m²/year than in those with an annual BMI change of < 0.25 kg/m²/year (7.7% vs. 35.0%, p = 0.011). Our findings suggest that age-related annual BMI gain between pregnancies may help prevent sPTB recurrence.

Biomarkers for Preterm Delivery

Preterm birth occurring before the thirty-seventh gestational week complicates 4.5%-18% of pregnancies worldwide. The pathogenesis of spontaneous preterm delivery is not fully understood. Among the factors held to be responsible for its pathogenesis, the most emphasized is the inflammatory process. Studies in terms of the prediction of preterm delivery are basically divided into 3 categories: 1) Prediction in pregnant women who are asymptomatic and without risk factors, 2) Prediction in pregnant women who are asymptomatic and have risk factors, 3) Prediction in symptomatic pregnant women who have threatened preterm labour. In this chapter, the topic of biomarkers in relation to preterm delivery is discussed. The most commonly used markers in published studies are fetal fibronectin, cervical pIGFBP-1 and cervical length measurement by transvaginal ultrasound. For prediction in symptomatic pregnant women applying to the hospital with threatened preterm labour, the markers used are fetal fibronection, insulin-like growth factors (IGFs) and inflammatory markers. Preterm labour prediction with markers checked in the first and second trimesters are fetal fibronection, insulin-like growth factors (IGFs), micro RNAs, progesterone, circulating microparticles (CMPs), inflammatory markers, matrix metalloproteinases, aneuploidy syndrome screening test parameters and other hormones.

Deprived neighborhoods and spontaneous preterm birth: A national cohort study

OBJECTIVE

Spontaneous preterm birth is the leading cause of infant morbidity and mortality in the developed world. Environmental socio-economic factors, such as neighborhood deprivation, are known to negatively affect birth outcomes, including overall preterm birth. However, the role of neighborhood deprivation in spontaneous preterm birth (SPTB) is unclear. The aim of the study is to 1) to determine the effect of neighborhood deprivation on SPTB birth and 2) to investigate the trend in rates of SPTB between 2010 and 2019 for each quintile of neighborhood deprivation.

STUDY DESIGN

Based on the national perinatal registry, we included 1,584,225 singleton pregnancies resulting in a birth from 22 to 42 completed weeks of gestation between 2010 and 2019 in the Netherlands. Deprivation scores per neighborhood were derived from the Netherlands Institute of Social Research and were linked to the perinatal registry data, using the woman's home address. The scores were divided into quintiles (Q). Rates of SPTB were calculated, categorized into <37 weeks, <32 weeks and <28 weeks of gestation. We used logistic regression analysis to adjust for maternal age, parity and ethnicity.

RESULTS

Compared to the most affluent neighborhoods (Q1), women in all other quintiles had a statistically significant increased risk for SPTB. The largest effect was observed in the most deprived neighborhoods (Q5); adjusted odds ratio 1.16 (95% confidence interval 1.13 - 1.19). From 2010 to 2019, we observed an overall decrease of 0.21% in SPTB < 37 weeks (p < 0.0001). All quintiles showed a decrease in SPTBs < 37 weeks, but only in Q1, Q2 & Q5 this decline in SPTB was statistically significant.

CONCLUSIONS

Pregnant women in deprived neighborhoods in the Netherlands are more at risk for spontaneous preterm birth. From 2010 to 2019, the rate of spontaneous preterm birth decreased. Efforts should be made by both governmental and medical professionals to develop intervention programs to reduce spontaneous preterm birth in more deprived neighborhoods.

Maternal perceived stress and the increased risk of preterm birth in a majority non-Hispanic Black pregnancy cohort

OBJECTIVE

To determine whether perceived stress is associated with preterm birth (PTB) and to investigate racial differences in stress and PTB.

STUDY DESIGN

A secondary analysis of a prospective cohort study of 1911 women with singleton pregnancies examined responses to psychosocial stress questionnaires at 16-20 weeks of gestation.

RESULTS

High perceived stress (19%) and PTB (10.8%) were prevalent in our sample (62% non-Hispanic Black). Women with PTB were more likely to be Black, have chronic hypertension (cHTN), pregestational diabetes, and higher BMI. Women with high perceived stress had more PTBs than those with lower stress (15.2% vs. 9.8%), and stress was associated with higher odds of PTB (aOR: 1.55, 95% CI: 1.09-2.19).

CONCLUSION

The significant association between high perceived stress and PTB suggests that prenatal interventions to reduce maternal stress could improve the mental health of pregnant women and may result in reduced rates of PTB.

Respiratory responses to hypoxia during rest and exercise in individuals born pre-term: a state-of-the-art review

The pre-term birth survival rate has increased considerably in recent decades, and research investigating the long-term effects of premature birth is growing. Moreover, altitude sojourns are increasing in popularity and are often accompanied by various levels of physical activity. Individuals born pre-term appear to exhibit altered acute ventilatory responses to hypoxia, potentially predisposing them to high-altitude illness. These impairments are likely due to the use of perinatal hyperoxia stunting the maturation of carotid body chemoreceptors, but may also be attributed to limited lung diffusion capacity and/or gas exchange inefficiency. Aerobic exercise capacity also appears to be reduced in this population. This may relate to the aforementioned respiratory impairments, or could be due to physiological limitations in pulmonary blood flow or at the exercising muscle (e.g. mitochondrial efficiency). However, surprisingly, the debilitative effects of exercise when performed at altitude do not seem to be exacerbated by premature birth. In fact, it is reasonable to speculate that pre-term birth could protect against the consequences of exercise combined with hypoxia. The mechanisms that underlie this assertion might relate to differences in oxidative stress responses or in cardiopulmonary morphology in pre-term individuals, compared to their full-term counterparts. Further research is required to elucidate the independent effects of neonatal treatment, sex differences and chronic lung disease, and to establish causality in some of the proposed mechanisms that could underlie the differences discussed throughout this review. A more in-depth understanding of the acclimatisation responses to chronic altitude exposures would also help to inform appropriate interventions in this clinical population.

Is there a maternal blood biomarker that can predict spontaneous preterm birth prior to labour onset? A systematic review

INTRODUCTION

The ability to predict spontaneous preterm birth (sPTB) prior to labour onset is a challenge, and it is currently unclear which biomarker(s), may be potentially predictive of sPTB, and whether their predictive power has any utility. A systematic review was conducted to identify maternal blood biomarkers of sPTB.

METHODS

This study was conducted according to PRISMA protocol for systematic reviews. Four databases (MEDLINE, EMBASE, CINAHL, Scopus) were searched up to September 2021 using search terms: "preterm labor", "biomarker" and "blood OR serum OR plasma". Studies assessing blood biomarkers prior to labour onset against the outcome sPTB were eligible for inclusion. Risk of bias was assessed based on the Newcastle Ottawa scale. Increased odds of sPTB associated with maternal blood biomarkers, as reported by odds ratios (OR), or predictive scores were synthesized. This review was not prospectively registered.

RESULTS

Seventy-seven primary research articles met the inclusion criteria, reporting 278 unique markers significantly associated with and/or predictive of sPTB in at least one study. The most frequently investigated biomarkers were those measured during maternal serum screen tests for aneuploidy, or inflammatory cytokines, though no single biomarker was clearly predictive of sPTB based on the synthesized evidence. Immune and signaling pathways were enriched within the set of biomarkers and both at the level of protein and gene expression.

CONCLUSION

There is currently no known predictive biomarker for sPTB. Inflammatory and immune biomarkers show promise, but positive reporting bias limits the utility of results. The biomarkers identified may be more predictive in multi-marker models instead of as single predictors. Omics-style studies provide promising avenues for the identification of novel (and multiple) biomarkers. This will require larger studies with adequate power, with consideration of gestational age and the heterogeneity of sPTB to identify a set of biomarkers predictive of sPTB.

The role of maternal age on the risk of preterm birth among singletons and multiples: a retrospective cohort study in Lombardy, Norther Italy

Background

All over the world, especially in the developed countries, maternal age at birth is rising. This study aimed to assess the role of maternal age on the occurrence of preterm birth (PTB) in a large birth cohort of Lombardy Region, Northern Italy.

Methods

This population-based study used data from regional healthcare utilization databases of Lombardy to identify women who delivered between 2007 and 2017. PTBs were defined as births before 37 completed weeks of gestation and considered according to the gestational age (two categories: < 32 weeks and 32 to 36 weeks). Six maternal age groups were defined (< 20, 20–24, 25–29, 30–34, 35–39, ≥40 years). Logistic regression models were fitted to estimate the crude and adjusted odds ratio (aOR) and the corresponding 95% confidence interval (CI) for PTB among different maternal age groups. Analyses were separately performed according to type of pregnancy (singletons and multiples). Reference group was the age group with the lowest frequency of PTB.

Results

Overall, 49,759 (6.6%) PTBs were observed, of which 41,807 were singletons and 7952 were multiples. Rates of PTB were lowest in the women aged 25–29 years among singletons and in the 30–34 years old group among multiples. Our results described a U-shaped association between maternal age and risk of PTB. In particular, the risk of a singleton PTB between 32 and 36 weeks was significantly higher for women aged less than 20 years (aOR = 1.16, CI 95%: 1.04–1.30) and more than 40 years (aOR = 1.62 CI 95%: 1.54–1.70). The highest risk of a multiple delivery between 32 and 36 weeks was observed among women aged less than 25 years and more than 40 years (aOR = 1.79, CI 95%: 1.01–3.17, aOR = 1.47, CI 95%: 1.16–1.85 and aOR = 1.36, CI 95%: 1.19–1.55 respectively for < 20, 20–24 and > 40 age categories). PTB before 32 completed weeks occurred more frequently in the same age categories, except that among multiples no association with advanced maternal age emerged.

Conclusion

Our study suggested that, after adjustment for potential confounders, both advance and young maternal age were associated with an increased risk of PTB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04552-y.

Understanding and Reducing Persistent Racial Disparities in Preterm Birth: a Model of Stress-Induced Developmental Plasticity

Preterm birth is a leading cause of neonatal mortality and is characterized by substantial racial disparities in the US. Despite efforts to reduce preterm birth, rates have risen and racial disparities persist. Maternal stress is a risk factor for preterm birth; however, often, it is treated as a secondary variable rather than a primary target for intervention. Stress is known to affect several biological processes leading to downstream sequelae. Here, we present a model of stress-induced developmental plasticity where maternal stress is a key environmental cue impacting the length of gestation and therefore a primary target for intervention. Black women experience disproportionate and unique maternal stressors related to perceived racism and discrimination. It is therefore not surprising that Black women have disproportionate rates of preterm birth. The downstream effects of racism on preterm birth pathophysiology may reflect an appropriate response to stressors through the highly conserved maternal-fetal-placental neuroendocrine stress axis. This environmentally sensitive system mediates both maternal stress and the timing of birth and is a mechanism by which developmental plasticity occurs. Fortunately, stress does not appear to be an all-or-none variable. Evidence suggests that developmental plasticity is dynamic, functioning on a continuum. Therefore, simple, stress-reducing interventions that support pregnant women may tangibly reduce rates of preterm birth and improve birth outcomes for all women, particularly Black women.

Clinical and economic evaluation of a proteomic biomarker preterm birth risk predictor: cost-effectiveness modeling of prenatal interventions applied to predicted higher-risk pregnancies within a large and diverse cohort

OBJECTIVES

Preterm birth occurs in more than 10% of U.S. births and is the leading cause of U.S. neonatal deaths, with estimated annual costs exceeding $25 billion USD. Using real-world data, we modeled the potential clinical and economic utility of a prematurity-reduction program comprising screening in a racially and ethnically diverse population with a validated proteomic biomarker risk predictor, followed by case management with or without pharmacological treatment.

METHODS

The ACCORDANT microsimulation model used individual patient data from a prespecified, randomly selected sub-cohort (N = 847) of a multicenter, observational study of U.S. subjects receiving standard obstetric care with masked risk predictor assessment (TREETOP; NCT02787213). All subjects were included in three arms across 500 simulated trials: standard of care (SoC, control); risk predictor/case management comprising increased outreach, education and specialist care (RP-CM, active); and multimodal management (risk predictor/case management with pharmacological treatment) (RP-MM, active). In the active arms, only subjects stratified as higher risk by the predictor were modeled as receiving the intervention, whereas lower-risk subjects received standard care. Higher-risk subjects' gestational ages at birth were shifted based on published efficacies, and dependent outcomes, calibrated using national datasets, were changed accordingly. Subjects otherwise retained their original TREETOP outcomes. Arms were compared using survival analysis for neonatal and maternal hospital length of stay, bootstrap intervals for neonatal cost, and Fisher's exact test for neonatal morbidity/mortality (significance, p < .05).

RESULTS

The model predicted improvements for all outcomes. RP-CM decreased neonatal and maternal hospital stay by 19% (p = .029) and 8.5% (p = .001), respectively; neonatal costs' point estimate by 16% (p = .098); and moderate-to-severe neonatal morbidity/mortality by 29% (p = .025). RP-MM strengthened observed reductions and significance. Point estimates of benefit did not differ by race/ethnicity.

CONCLUSIONS

Modeled evaluation of a biomarker-based test-and-treat strategy in a diverse population predicts clinically and economically meaningful improvements in neonatal and maternal outcomes.

Explaining the Black-White Disparity in Preterm Birth: A Consensus Statement From a Multi-Disciplinary Scientific Work Group Convened by the March of Dimes

In 2017-2019, the March of Dimes convened a workgroup with biomedical, clinical, and epidemiologic expertise to review knowledge of the causes of the persistent Black-White disparity in preterm birth (PTB). Multiple databases were searched to identify hypothesized causes examined in peer-reviewed literature, 33 hypothesized causes were reviewed for whether they plausibly affect PTB and either occur more/less frequently and/or have a larger/smaller effect size among Black women vs. White women. While definitive proof is lacking for most potential causes, most are biologically plausible. No single downstream or midstream factor explains the disparity or its social patterning, however, many likely play limited roles, e.g., while genetic factors likely contribute to PTB, they explain at most a small fraction of the disparity. Research links most hypothesized midstream causes, including socioeconomic factors and stress, with the disparity through their influence on the hypothesized downstream factors. Socioeconomic factors alone cannot explain the disparity's social patterning. Chronic stress could affect PTB through neuroendocrine and immune mechanisms leading to inflammation and immune dysfunction, stress could alter a woman's microbiota, immune response to infection, chronic disease risks, and behaviors, and trigger epigenetic changes influencing PTB risk. As an upstream factor, racism in multiple forms has repeatedly been linked with the plausible midstream/downstream factors, including socioeconomic disadvantage, stress, and toxic exposures. Racism is the only factor identified that directly or indirectly could explain the racial disparities in the plausible midstream/downstream causes and the observed social patterning. Historical and contemporary systemic racism can explain the racial disparities in socioeconomic opportunities that differentially expose African Americans to lifelong financial stress and associated health-harming conditions. Segregation places Black women in stressful surroundings and exposes them to environmental hazards. Race-based discriminatory treatment is a pervasive stressor for Black women of all socioeconomic levels, considering both incidents and the constant vigilance needed to prepare oneself for potential incidents. Racism is a highly plausible, major upstream contributor to the Black-White disparity in PTB through multiple pathways and biological mechanisms. While much is unknown, existing knowledge and core values (equity, justice) support addressing racism in efforts to eliminate the racial disparity in PTB.

Healthy dietary patterns and common pregnancy complications: a prospective and longitudinal study

BACKGROUND

Adherence to alternate Healthy Eating Index (AHEI), alternate Mediterranean diet (AMED), and Dietary Approaches to Stop Hypertension (DASH) has been linked to lower risks of chronic diseases. However, their associations with common pregnancy complications are unclear.

OBJECTIVES

This study investigates the associations of AHEI, AMED, and DASH during periconception and pregnancy with common pregnancy complication risks.

METHODS

The study included 1887 pregnant women from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singletons. Women responded to an FFQ at 8-13 gestational weeks, and they performed a 24-h dietary recall at 16-22 and 24-29 wk. Gestational diabetes (GDM), gestational hypertension, preeclampsia, and preterm delivery were ascertained using medical records.

RESULTS

Healthier diet indicated by higher AHEI, AMED, and DASH scores was generally related to lower risks of pregnancy complications. Significant inverse associations were observed between AHEI score reported at 16-22 wk and GDM risk [adjusted RR (95% CI), highest (Q4) vs. lowest quartile (Q1): 0.32 (0.16, 0.66), P-trend = 0.002]; DASH score reported at both 8-13 [adjusted RR (95% CI), Q4 vs. Q1: 0.45 (0.17, 1.17), P-trend = 0.04] and 16-22 wk [adjusted RR (95% CI), Q4 vs. Q1: 0.19 (0.05, 0.65), P-trend = 0.01] and gestational hypertension risk; AHEI score reported at 24-29 wk and preeclampsia risk [adjusted RR (95% CI), Q4 vs. Q1: 0.31 (0.11, 0.87), P-trend = 0.03]; AMED score reported at 8-13 wk [adjusted RR (95% CI), Q4 vs. Q1: 0.50 (0.25, 1.01), P-trend = 0.03] and DASH score reported at 24-29 wk [adjusted RR (95% CI), Q4 vs. Q1: 0.50, (0.26, 0.96), P-trend = 0.03] and preterm delivery risk.

CONCLUSIONS

Adherence to AHEI, AMED, or DASH during periconception and pregnancy was related to lower risks of GDM, gestational hypertension, preeclampsia, and preterm delivery.This study was registered at ClinicalTrials.gov as NCT00912132.

Preterm births in China between 2012 and 2018: an observational study of more than 9 million women

BACKGROUND

Preterm birth rates have increased significantly worldwide over the past decade. Few epidemiological studies on the incidence of preterm birth and temporal trends are available in China. This study used national monitoring data from China's National Maternal Near Miss Surveillance System (NMNMSS) to estimate the rate of preterm birth and trends between 2012 and 2018 in China and to assess risk factors associated with preterm birth.

METHODS

In this observational study, data were sourced from the NMNMSS between Jan 1, 2012, and Dec 31, 2018. Pregnancies with at least one livebirth, with the baby born at 28 weeks of gestation or more or 1000 g or more birthweight were included. We estimated the rates of overall preterm, very preterm (born between 28 and 31 weeks' gestation), moderate preterm (born between 32 and 33 weeks' gestation), and late preterm (born between 34 and 36 weeks' gestation) births in singleton and multiple pregnancies and assessed their trends over time. We used logistic regression analysis to examine the associations between preterm birth and sociodemographic characteristics and obstetric complications, considering the sampling strategy and clustering of births within hospitals. Interrupted time series analysis was used to assess the changes in preterm birth rates during the period of the universal two child policy intervention.

FINDINGS

From Jan 1, 2012, to Dec 31, 2018, 9 645 646 women gave birth to at least one live baby, of whom 665 244 (6·1%) were born preterm. In all pregnancies, the overall preterm birth rate increased from 5·9% in 2012 to 6·4% in 2018 (8·8% increase; annual rate of increase [ARI] 1·3 [95% CI 0·6 to 2·1]). Late preterm births (8·8%; ARI 1·5% [0·9 to 2·2]) and very preterm births (13·3%; ARI 1·8% [0·5 to 3·0]) significantly increased from 2012 to 2018, whereas moderate preterm births did not (3·8%; ARI 0·3% [95% CI -0·9 to 1·5]). In singleton pregnancies, the overall preterm birth rate showed a small but significant 6·4% increase (ARI 1·0% [0·4 to 1·7]) over the 7 year period. In multiple pregnancies, the overall preterm birth rate significantly increased from 46·8% in 2012 to 52·7% in 2018 (12·4% increase; ARI 1·9% [1·2 to 2·6]). Compared with women who gave birth in 2012, those who gave birth in 2018 were more likely to be older (aged ≥35 years; 7·4% in 2012 vs 15·9% in 2018), have multiples (1·6% vs 1·9%), have seven or more antenatal visits (50·2% vs 70·7%), and have antepartum complications and medical disease (17·9% vs 35·1%), but they were less likely to deliver via caesarean section (47·5% vs 45·0%). Compared with the baseline period (January, 2012 to June, 2016), a higher increase in preterm birth was observed after the universal two child policy came into effect in July, 2016 (β=0·034; p=0·03).

INTERPRETATION

An increase in preterm births was noted for both singleton and multiple pregnancies between 2012 and 2018 in China. China's strategic investment in maternal and neonatal health has been crucial for the prevention of preterm birth. Due to rapid changes in sociodemographic and obstetric factors related to preterm birth-particularly within the context of the universal two child policy-such as advanced maternal age at delivery, maternal complications, and multiple pregnancies, greater efforts to reduce the burden of preterm birth are urgently needed.

FUNDING

National Key R&D Program of China, National Health Commission of the People's Republic of China, China Medical Board, WHO, and UNICEF.

Late preterm births: neonatal mortality and morbidity in twins vs. singletons

OBJECTIVE

To examine the outcomes of twins and singletons in the late preterm period.

MATERIALS AND METHODS

This is a retrospective cohort study of data obtained for 165,894 births in California who delivered between 34 + 0 and 36 + 6 weeks. The primary outcome was neonatal and infant mortality. The secondary outcomes included the following neonatal morbidities: respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), seizure, and sepsis. Univariate analysis was performed using chi-square test and multivariable logistic regression was used to adjust for potential confounders.

RESULTS

There were 143,891 singleton and 22,003 twin gestations included in the study. There was no difference in the primary outcome, neonatal and infant mortality between twins and singletons delivered at 34 and 36 weeks. After controlling for multiple potential confounders, significant differences in secondary outcomes of neonatal morbidity were identified. At 34 weeks, twins had significantly higher rates of IVH (aOR 2.47 (95%CI 1.08-5.64)), NEC (aOR 2.46 (95%CI 1.42-4.29)), RDS (aOR 1.60 (95%CI 1.45-1.77)), and sepsis (aOR 1.19 (95%CI 1.05-1.34)) compared to singletons. By 36 weeks, only an increased risk of RDS persisted among twins.

CONCLUSIONS

While there was no difference in mortality among twins and singletons in the late preterm period, twins may have significantly increased neonatal morbidity compared to singletons delivered between 34 + 0 and 36 + 6 weeks.

Stability of Executive Functioning of Moderately-Late Preterm and Full-Term Born Children at Ages 11 and 19: The TRAILS Cohort Study

Moderately-late preterm-born children (MLPs, 32-36 weeks gestational age, GA) have poorer executive functioning (EF) at primary school age than full-term children (FTs). Evidence is lacking on their EF in adolescence, but for early preterm-born children, this has been shown to be much poorer. We, therefore, compared EF of MLPs and FTs at ages 11 and 19 and assessed development between these ages. We obtained data from TRAILS, a community-based prospective cohort study in the northern Netherlands, on 98 MLPs and 1832 FTs. We assessed EF by the Amsterdam Neuropsychological Tasks (ANT) at ages 11 and 19 years and computed gender-specific z-scores on reaction time and accuracy. We compared baseline speed, pattern search, working memory, sustained attention, inhibition, and attentional flexibility of MLPs and FTs crude, and adjusted for small-for-GA status, socioeconomic status, and estimated intelligence. MLPs and FTs performed similarly on all EF components at ages 11 and 19, except for the speed, but not the accuracy measure of attentional flexibility. This was slightly poorer for MLPs than FTs at age 19 (adjusted B 0.25; 95% confidence interval: 0.00 to 0.50; p = 0.047), but not at age 11 (adjusted B -0.02; -0.19 to 0.22; p = 0.87). Differences in EF between MLPs and FTs did not change significantly from age 11 to 19. MLPs had comparable EF on most components as FTs, with only attentional flexibility at age 19 developing slightly poorer for MLPs than for FTs. These findings suggest the effects of MLP birth on long-term EF to be small.

Iatrogenic vs. Spontaneous Preterm Birth: A Retrospective Study of Neonatal Outcome Among Very Preterm Infants

Objective: Preterm birth is a leading contributor to childhood morbidity and mortality, and the incidence tends to increase and is higher in developing countries. The aim of this study was to analyze the potential impact of preterm birth in different etiology groups on neonatal complications and outcomes and to gain insight into preventive strategies.

Methods: We performed a retrospective cohort study of preterm infants less than 32 weeks' gestation in the Third Affiliated Hospital of Zhengzhou University from 2014 to 2019. Preterm births were categorized as spontaneous or iatrogenic, and these groups were compared for maternal and neonatal characteristics, neonatal complications, and outcomes. All infants surviving at discharge were followed up at 12 months of corrected age to compare the neurodevelopmental outcomes.

Results: A total of 1,415 mothers and 1,689 neonates were included, and the preterm population consisted of 1,038 spontaneous preterm infants and 651 iatrogenic preterm infants. There was a significant difference in the incidence of small for gestational age between the two groups. Infants born following spontaneous labor presented with a higher risk of intraventricular hemorrhage, whereas iatrogenic preterm birth was associated with higher risk of necrotizing enterocolitis and coagulopathy and higher risk of pathoglycemia. There was no difference in mortality between the two groups. Follow-up data were available for 1,114 infants, and no differences in neurologic outcomes were observed between the two preterm birth subtypes.

Conclusions: Preterm births with different etiologies were associated with some neonatal complications, but not with neurodevelopmental outcomes at 12 months of corrected age.

Temporal trends in preterm birth phenotypes by plurality: Black-White disparity over half a century

OBJECTIVE

To examine trends in rates of preterm birth by race and plurality; to evaluate the association between race, plurality, and phenotypes of preterm birth.

STUDY DESIGN

Temporal trends analyses for preterm birth by race and plurality were performed for the years 1971-2018. Adjusted logistic regression models were utilized to evaluate the association between race, plurality, and phenotypes of preterm birth.

RESULTS

We observed that 1105,266 (0.7%), 1901,604 (1.2%), and 14,769,746 (9.3%) births belonged to extreme preterm, very preterm, and moderate-to-late preterm categories, respectively. We also observed that the risk of extreme preterm (RR: 2.69, 95% CI: 2.642-2.75) was highest for Black mothers as compared to White mothers.

CONCLUSION

Over the study period, preterm births disproportionately impacted Black mothers as well as pregnancies of higher plurality. With the persistence of racial disparities and growing trend of delayed childbearing and multiple pregnancies, targeted intervention is necessitated toward these vulnerable subgroups.

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

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

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

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

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

[Teenage pregnancy and prematurity in Brazil, 2011-2012]

The study aims to evaluate the association between teenage pregnancy and prematurity. The data are from the Birth in Brazil study, a national survey consisting of 23,894 postpartum women and their newborn infants. The information was obtained from interviews with the mothers during their postpartum hospital stay. A matching method was established, based on propensity scores, to deal with differences between the groups due to the non-experimental design of the Birth in Brazil study. The study outcome was gestational age, considering all the premature births (gestational age < 37 weeks) and term births (gestational age 37 weeks to 41 weeks and 6 days). The study revealed social, economic, and maternal care disparities between the women according to age bracket. The highest proportions of teenage mothers were in the least developed regions of Brazil (North and Northeast) and in the poorest economic classes. After matching for socioeconomic and obstetric care characteristics, the highest odds of spontaneous prematurity were seen in younger adolescents compared to older adolescents (OR = 1.49; 95%CI: 1.07-2.06), and young adults (OR = 2.38; 95%CI: 1.82-3.12). Prematurity is still an issue in the field of maternal and child health, and the association with teenage pregnancy identified in this study is worrisome, especially because younger adolescent mothers were associated with higher odds of spontaneous prematurity.

Current Preterm Birth Prevention Strategies

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

Should we adjust for delivery hospital in studies of air pollution and pregnancy outcomes?

Background:

In conducting a study of ambient air pollution and pregnancy outcome in New York City, we identified delivery hospital as a potential confounder, given its association with both maternal residence and therefore air pollution exposure, and with clinical practices and as a potential marker of outcome misclassification in the coding of pregnancy complications. Motivated by evidence that adjustment for delivery hospital affected associations between air pollution and pregnancy outcome, we undertook a detailed empirical examination of the role of delivery hospital that warrants consideration by others addressing this topic.

Methods:

In a study of air pollution and pregnancy outcome, we identified births from 2008 to 2010 to residents of New York City and, after restrictions, included 238,960 in the analysis. Air pollution exposure estimates for ambient fine particles (PM_2.5) and nitrogen dioxide (NO₂) were derived from a community-wide exposure study and assigned based on geocoded maternal residence. We examined the impact of adjusting for delivery hospital and explored the relationship between delivery hospital and both exposure and pregnancy outcomes.

Results:

Statistical adjustment for delivery hospital markedly attenuated the relationship of air pollution with birth weight and gestational hypertension, with smaller effects on preterm birth and preeclampsia. Delivery hospital was associated with estimated maternal air pollution levels after adjusting for individual-level patient characteristics, more strongly for PM_2.5 than for NO₂. Delivery hospital predicted pregnancy outcome after adjustment for individual attributes, with larger hospitals and those that managed a greater volume of complicated cases having lower birth weight, more medically indicated preterm births, and more diagnosed gestational hypertension. Evaluation through the use of directed acyclic graphs illustrates the potential for adjustment for hospital to reduce residual spatial confounding, but also indicates the possibility of introducing bias through adjustment of a mediator.

Conclusions:

Based on these results, delivery hospital warrants closer consideration in studies of air pollution and other spatial factors in relation to pregnancy outcomes. The possibility of confounding by delivery hospital needs to be balanced with the risk of adjusting for a mediator of the air pollution—pregnancy outcome association in studies of this type.

A Multisite Examination of Everyday Discrimination and the Prevalence of Spontaneous Preterm Birth in African American and Latina Women in the United States

OBJECTIVE

African American women have a higher risk of spontaneous preterm birth than White and Latina women. Although Latina women are exposed to similar social determinants of health, they have lower rates of spontaneous preterm birth. One theory for this difference is the maternal stress biological pathway, whereby lifetime stressors, such as racial discrimination, lead to a premature activation of parturition. We investigated the prevalence of self-reported discrimination and its association with the prevalence of spontaneous preterm birth.

STUDY DESIGN

Using data from the Community Child Health Research Network Study, a multisite cohort study from 2008 to 2012, we conducted a cross-sectional analysis of 1,154 African American women and 578 Latina women.

RESULTS

Adjusting for multiple risk factors, African American and Latina women who experienced the highest tertile of discrimination had a higher prevalence of preterm birth compared with those who experienced discrimination less than once per year, adjusted hazard ratio (aHR) = 1.5 (0.7-3.1) and 3.6 (0.9-14.4), respectively.

CONCLUSION

In our cohort, we found a statistically significant association only in the medium discrimination group in Latina women, but we did not find a statistically significant association in African American women. Reduction in experienced discrimination may be an important intervention for reducing adverse pregnancy outcomes.

Preterm parturition and pre-eclampsia: The confluence of two great gestational syndromes

BACKGROUND

Preterm birth (PTB) and pre-eclampsia independently, and frequently concurrently, adversely affect the pregnancy outcomes of millions of mothers and infants worldwide each year.

OBJECTIVES

To fill the gap between PTB and pre-eclampsia, which continue to constitute the two most important current global challenges to maternal and perinatal health.

METHODS

Pubmed, Embase, and Cochrane databases were searched from inception until December 2019 using the terms spontaneous PTB (SPTB), indicated preterm delivery (IPTD), early-onset pre-eclampsia, and pre-eclampsia.

RESULTS

History of PTB and pre-eclampsia were the strongest risk factors contributing to the occurrence of SPTB or IPTB. The risk of PTB and pre-eclampsia among non-Hispanic African American women was higher than the rate among all other racial/ethnic groups in the United States. Low-dose aspirin (LDA) has been reported to reduce the risk of pre-eclampsia by at least 10% and PTB by at least 14%. Lastly, women and their fetuses who develop early-onset pre-eclampsia are at higher risk for developing hypertension and cardiovascular disease later in life.

CONCLUSIONS

While better clarity is needed, efforts to coordinate prevention of both PTB and pre-eclampsia, even though imperfect, are critically important as part of any program to make motherhood as safe as possible.

Outcomes of prenatally diagnosed spontaneous chorioamniotic membrane separation in singleton pregnancies: A systematic review of case series and case reports

OBJECTIVES

To provide an overview of perinatal outcomes in prenatally diagnosed spontaneous chorioamniotic separation (sCAS).

METHODS

A systematic search of the literature was performed from inception to July 2019, including PubMed, Ovid MEDLINE, and Ovid EMBASE. All studies reporting prenatally diagnosed sCAS after 16 weeks' gestation in singleton pregnancies were eligible. Two independent reviewers used standardized forms for data abstraction.

RESULTS

Of 408 screened abstracts, 17 studies reporting 118 cases of sCAS were included. Among 113 cases with delivery outcomes, preterm birth (PTB) occurred in 60 (53.1%, 95% confidence interval [CI] 43.9-62.3%). Intrauterine fetal demise (IUFD) occurred in seven (6.2%, 95% CI 1.8-10.6%) cases, with four due to cord strangulation. Spontaneous abortion occurred in one (0.88%, 95% CI -0.84-2.6%) case. Among 104 cases with postnatal follow-up, there were six (5.8%, 95% CI 1.3-10.3%) neonatal deaths and one (0.96%, 95% CI -0.91-2.8%) infant death. Perinatal mortality (IUFD and neonatal deaths) was 11.0% (95% CI 5.4-16.7%).

CONCLUSIONS

sCAS may be associated with increased risk of PTB, however, the available data are largely case reports and series. Antepartum surveillance after viability can be considered due to risk of cord accidents. Prospective study is necessary to understand the clinical implications of sCAS.

Performance of a proteomic preterm delivery predictor in a large independent prospective cohort

BACKGROUND

Preterm birth remains a common and devastating complication of pregnancy. There remains a need for effective and accurate screening methods for preterm birth. Using a proteomic approach, we previously discovered and validated (Proteomic Assessment of Preterm Risk study, NCT01371019) a preterm birth predictor comprising a ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin.

OBJECTIVE

To determine the performance of the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin to predict both spontaneous and medically indicated very preterm births, in an independent cohort distinct from the one in which it was developed.

STUDY DESIGN

This was a prospective observational study (Multicenter Assessment of a Spontaneous Preterm Birth Risk Predictor, NCT02787213) at 18 sites in the United States. Women had blood drawn at 17^0/7 to 21^6/7 weeks' gestation. For confirmation, we planned to analyze a randomly selected subgroup of women having blood drawn between 19^1/7 and 20^6/7 weeks' gestation, with the results of the remaining study participants blinded for future validation studies. Serum from participants was analyzed by mass spectrometry. Neonatal morbidity and mortality were analyzed using a composite score by a method from the PREGNANT trial (NCT00615550, Hassan et al). Scores of 0-3 reflect increasing numbers of morbidities or length of neonatal intensive care unit stay, and 4 represents perinatal mortality.

RESULTS

A total of 5011 women were enrolled, with 847 included in this planned substudy analysis. There were 9 preterm birth cases at <32^0/7 weeks' gestation and 838 noncases at ≥32^0/7 weeks' gestation; 21 of 847 infants had neonatal composite morbidity and mortality index scores of ≥3, and 4 of 21 had a score of 4. The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio was substantially higher in both preterm births at <32^0/7 weeks' gestation and there were more severe neonatal outcomes. The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio was significantly predictive of birth at <32^0/7 weeks' gestation (area under the receiver operating characteristic curve, 0.71; 95% confidence interval, 0.55-0.87; P=.016). Stratification by body mass index, optimized in the previous validation study (22<body mass index≤37 kg/m²), resulted in an area under the receiver operating characteristic curve of 0.76 (95% confidence interval, 0.59-0.93; P=.023). The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio predicted neonatal outcomes with respective area under the receiver operating characteristic curve of 0.67 (95% confidence interval, 0.57-0.77; P=.005) and 0.78 (95% confidence interval, 0.63-0.93; P=.026) for neonatal composite morbidity and mortality scores of ≥3 or 4. In addition, the ratio of insulin-like growth factor-binding protein 4 to sex hormone binding globulin significantly stratified neonates with increased length of hospital stay (log rank P=.023).

CONCLUSION

We confirmed in an independent cohort the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio as a predictor of very preterm birth, with additional prediction of increased length of neonatal hospital stay and increased severity of adverse neonatal outcomes. Potential uses of the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin predictor may be to risk stratify patients for implementation of preterm birth preventive strategies and direct patients to appropriate levels of care.

Distribution of uterocervical angles in the second trimester of pregnant women at low risk for preterm delivery

The uterocervical angle (UCA) has recently been studied as a parameter to identify women at risk for spontaneous preterm birth (sPTB). This study aimed to investigate the distribution of UCA values by transvaginal sonography (TVS) in the second trimester of women at low risk for sPTB. TVS was performed in 450 low-risk pregnant women at gestational age (GA) 16^0/7-24^0/7weeks. The UCA distribution by GA was visualised using a scatter plot. The range of UCA values and their relationship with GA were assessed using quantile regression analysis. p < .05 was considered statistically significant. A total of 242 participants with anteflexed uterus, no history of caesarean section and term delivery were analysed. The normal range of UCA (5th and 95th percentiles) was from 63.0 degrees (95% CI, 53.1-72.9) to 148.8 degrees (95% CI, 139.5-158.0) with no significant changes during this GA period (-0.3 degrees per week, p = .757).Impact statementWhat is already known on this subject? Spontaneous preterm birth (sPTB) is a major problem in obstetrics. A screening strategy using history of sPTB and cervical length (CL) measurement is the current standard to identify women at risk for sPTB and provide adequate prevention. However, a third of women who are identified as low risk go on to have sPTB, so a better means needs to be found to more reliably identify women at risk. Various studies have found that a wide uterocervical angle (UCA) was associated with sPTB, and thus the UCA has been proposed as a potential sPTB screening parameter. However, to date there is a lack of prospective studies evaluating this proposal, and no consensus about the proper gestational age to perform UCA measurements to identify women at risk of sPTB.What do the results of this study add? This study reports the distribution of UCA at the GA of 16^0/7-24^0/7 weeks of low-risk singleton pregnancy women who delivered at term. The mid-90% values ranged from 63.0 degrees to 148.8 degrees with no significant differences in this GA period.What are the implications of these findings for clinical practice and/or further research? Because of the wide range of UCA values at GA 16^0/7-24^0/7 weeks, more studies regarding UCA values in various gestational ages are required to fully understand the trend of UCA values along pregnancy and confirm whether or not the UCA would be a useful parameter for sPTB prediction and if so at what gestational age it would have to be assessed.

Trends in preterm birth in singleton and multiple gestations in the Netherlands 2008-2015: A population-based study

OBJECTIVE

Preterm birth is the most important cause of perinatal morbidity and mortality. Over the past years several preventive measures have been studied and implemented. Preterm birth percentage in 2015 in the Netherlands was 6.9 %, according to data from the European Peristat project, reporting on perinatal health in Europe. Various preventive measures might have influenced the incidence and outcome of preterm birth. Our aim was to give an overview of the trends in preterm births for both singleton and multiple gestations in the Netherlands in order to guide future research.

STUDY DESIGN

We studied a nationwide cohort including both singleton and multiple gestations without congenital anomalies between 2008 and 2015. Outcomes were total preterm birth (defined as birth before 37 weeks of gestation), spontaneous and iatrogenic preterm birth < 37 weeks, spontaneous and iatrogenic preterm birth percentages between 34-36 weeks, 32-34 weeks, 28-31 weeks and ≤ 27 weeks using a moving average technique. Trend analysis was performed using the Cochran Armitage test. Singleton and multiple gestations were analyzed separately.

RESULTS

Our final study population comprised 1,303.786 women with a singleton and 44,951 women with a multiple pregnancy. Preterm birth < 37 weeks in singletons decreased from 5.6 % in 2008 to 5.3 % in 2015 (P < 0.0001), in both spontaneous and iatrogenic preterm birth. Preterm birth ≤ 27 weeks increased from 0.40 % to 0.45 % (P for trend <0.0001). The number of multiple gestations decreased over the years, as well as the percentage of multiples conceived through IVF/ICSI. There was an increase in total and iatrogenic preterm birth < 37 weeks from 36.7-38.2% (P < 0.0001) in multiples. The number of multiples <32 decreased, in both the spontaneous and iatrogenic group.

CONCLUSION

In the Netherlands preterm birth risk in singletons decreased between 2008 and 2015 but an increase was noted in preterm birth ≤ 27 weeks. In multiples the total preterm birth risk increased, due to an increase in indicated preterm birth.

Reducing the Risk of Preterm Birth by Ambulatory Risk Factor Management

BACKGROUND

The preterm birth rate in Germany has remained unchanged at 8-9% since 2009. Preterm birth is the most common cause of neonatal morbidity and mortality. In the absence of a causal treatment, it is important to lower the risk of preterm birth by preventive measures in prenatal outpatient care.

METHODS

This review is based on pertinent publications from the years 2000-2019 that were retrieved by a selective search in PubMed.

RESULTS

The clinical risk factors for preterm birth-known mainly from retrospective cohort studies-include previous preterm birth (adjusted odds ratio [aOR]: 3.6), multiple pregnancy (relative risk [RR]: 7.7), nicotine consumption (aOR: 1.7), and a short uterine cervix, i.e., <25 mm in the second trimester (aOR: 6.9). In women with a short cervix, vaginally administered progesterone significantly lowers the preterm birth rate (22.5% vs. 14.1% for birth before 33 weeks of gestation, RR: 0.62; 95% confidence interval [0.47; 0.81]). Nicotine abstinence is associated with a lower pre- term birth rate as well (aOR: 0.91; [0.88; 0,.94]), while working more than 40 hours per week (aOR: 1.25; [1,.01; 1,.54]) and heavy lifting during pregnancy (hazard ratio [HR]: 1.43; [1.13; 1.80]) are associated with a higher preterm birth rate. Avoidance of physical exertion, or bed rest, in the face of impending preterm birth does not lower the preterm birth rate, but it does increase the risk of complications, such as thromboembolism.

CONCLUSION

The meticulous assessment and elimination of treatable risk factors at the outset of ambulatory prenatal care can help lower the preterm birth rate. Further velopment of causally directed treat- ments (e.g., changes of relevant environmental and epigenetic factors).

Induction of labor and early-onset Sepsis guidelines: impact on NICU admissions in Erie County, NY

BACKGROUND

Elective delivery prior to term gestation is associated with adverse neonatal outcomes. The impact of American College of Obstetricians and Gynecologists (ACOG) guidelines recommending against induction of labor (IOL) < 39 weeks' postmenstrual age (PMA) on the frequency of early-term births and NICU admissions in Erie County, NY was evaluated in this study.

METHODS

This is a population-based retrospective comparison of all live births and NICU admissions in Erie County, NY between pre-and post-ACOG IOL guideline epochs (2005-2008 vs. 2011-2014). Information on early-term, full/late/post-term births and NICU admissions was obtained. A detailed chart analysis of indications for admission to the Regional Perinatal Center was performed.

RESULTS

During the 2005-2008 epoch, early-term births constituted 27% (11,968/44,617) of live births. The NICU admission rate was higher for early-term births (1134/11968 = 9.5%) compared to full/late/post-term (1493/27541 = 5.4%).In the 2011-2014 epoch, early-term births decreased to 23% (10,286/44,575) of live births. However, NICU admissions for early-term (1072/10286 = 10.4%) and full/late/post-term births (1892/29508 = 6.4%) did not decrease partly due to asymptomatic infants exposed to maternal chorioamnionitis admitted for empiric antibiotic therapy as per revised early-onset sepsis guidelines.

CONCLUSIONS

ACOG recommendations against elective IOL or cesarean delivery < 39 weeks PMA were rapidly translated to clinical practice and decreased early-term births in Erie County, NY. This decrease did not translate to reduced NICU admissions partly due to increased NICU admissions for empiric antibiotic therapy.

Impact of the new guidelines on the management of premature rupture of membranes for the prevention of late preterm birth: an 11-year retrospective study

Objectives To evaluate the number of late preterm (LPT) births (between 34 0/7 and 36 6/7 weeks) that could have been prevented if expectant management of preterm premature rupture of membranes (PPROM) had been applied according to new recommendations. Methods A retrospective cohort study included all births at one Swiss center between January 1, 2002 and December 31, 2012. Births were categorized using an adapted evidence-based classification. Two scenarios were considered: best scenario (maximum averted cases) and a conservative scenario (minimum averted cases). Results Among 2017 LPT births (5.0% of all deliveries; n=40,609), 1122 (60.6%) women had PPROM. Spontaneous labor occurred in 473 (42.2%) cases and 649 (57.8%) had induction of labor or an elective cesarean section. In the latter group, 44 (6.8%) had evidence-based indications for LPT delivery and 605 (83.2%) had non-evidence-based indications. Depending on the scenario, the rate of avoided LPT cases would have varied between 4.2% (95% confidence interval [CI]: 3.4-5.2) if the conservative scenario was applied, and 30% (95% CI: 28.0-32.0) for the best scenario. Conclusion Adoption of new guidelines for the management of PPROM will prevent a considerable number of LPT births and help decrease the adverse effects and potential disability associated with late preterm infants.

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.

Epidemiology of late preterm and early term births - An international perspective

Late preterm (34-36 weeks of gestational age (GA)), and early term (37-38 weeks GA) birth rates among singleton live births vary from 3% to 6% and from 15% to 31%, respectively, across countries, although data from low- and middle-income countries are sparse. Countries with high preterm birth rates are more likely to have high early term birth rates; many risk factors are shared, including pregnancy complications (hypertension, diabetes), medical practices (provider-initiated delivery, assisted reproduction), maternal socio-demographic and lifestyle characteristics and environmental factors. Exceptions include nulliparity and inflammation which increase risks for preterm, but not early term birth. Birth before 39 weeks GA is associated with adverse child health outcomes across a wide range of settings. International rate variations suggest that reductions in early delivery are achievable; implementation of best practice guidelines for obstetrical interventions and public health policies targeting population risk factors could contribute to prevention of both late preterm and early term births.

Urinary oxidative stress biomarkers and accelerated time to spontaneous delivery

BACKGROUND

Oxidative stress has been implicated in numerous birth outcomes, including spontaneous preterm birth. However, the relationship with presentation at delivery has been less well studied. We assessed the relationship between oxidative stress biomarkers and gestational duration with a focus on spontaneous presentation for delivery.

METHODS

Our sample included 740 women from a multi-center prospective cohort study, recruited from 2010 to 2012. Resultant measures of oxidative stress in pregnancy prostaglandin F_2α (PGF_2α), 8-iso-prostaglandin F_2α (8-iso-PGF_2α), and the primary 8-iso-PGF_2α metabolite were measured in third trimester urine samples. Information on presentation for delivery was abstracted from medical records. We examined associations with preterm birth using adjusted logistic models. Time to event (overall delivery and spontaneous delivery) was examined using adjusted accelerated failure time models.

RESULTS

The 8-iso-PGF_2α metabolite was associated with increased odds of overall preterm birth (OR: 1.44 [95% CI: 1.00, 2.06]), and the association with spontaneous preterm birth was similar in magnitude but not statistically significant (OR: 1.45 [95% CI: 0.96, 2.20]). We did not detect associations between other biomarkers and preterm birth, or between biomarkers and timing of overall or spontaneous delivery in accelerated failure time models.

CONCLUSIONS

Our data suggest that increased oxidative stress, as indicated by the 8-iso-PGF_2α metabolite, may be associated with preterm birth. In contrast to previous studies, associations were similar among individuals with spontaneous versus non-spontaneous presentation for delivery.