Heterogeneity of Perinatal Outcomes in the Preterm Delivery Syndrome

Etiologically Based Functional Taxonomy of the Preterm Birth Syndrome

Preterm birth (PTB) is a complex syndrome traditionally defined by a single parameter, namely, gestational age at birth (ie, ˂37 weeks). This approach has limitations for clinical usefulness and may explain the lack of progress in identifying cause-specific effective interventions. The authors offer a framework for a functional taxonomy of PTB based on (1) conceptual principles established a priori; (2) known etiologic factors; (3) specific, prospectively identified obstetric and neonatal clinical phenotypes; and (4) postnatal follow-up of growth and development up to 2 years of age. This taxonomy includes maternal, placental, and fetal conditions routinely recorded in data collection systems.

Economic burden of adverse perinatal outcomes from births to age 5 years in high-income settings: a protocol for a systematic review

BACKGROUND

Adverse perinatal outcomes such as preterm, small for gestational age, low birth weight, congenital anomalies, stillbirth and neonatal death have devastating impacts on individuals, families and societies, with significant lifelong health implications. Despite extensive knowledge of the significant and lifelong health implications of adverse perinatal outcomes, information on the economic burden is limited. Estimating this burden will be crucial for designing cost-effective interventions to reduce perinatal morbidity and mortality. Thus, we will quantify the economic burden of adverse perinatal outcomes from births to age 5 years in high-income countries.

METHODS AND ANALYSIS

A systematic review of all primary studies published in English in peer-reviewed journals on the economic burden for at least one of the adverse perinatal outcomes in high-income countries from 2010 will be searched in databases-MEDLINE (Ovid), EconLit, CINAHL (EBSCO), Embase (Ovid) and Global Health (Ovid). We will also search using Google Scholar and snowballing of the references list of included articles. The search terms will include three main concepts-costs, adverse perinatal outcome(s) and settings. We will use the Consolidated Health Economics Evaluation Reporting Standards 2022 and 17 criteria from the critical appraisal of cost-of-illness studies to assess the quality of each study. We will report the findings based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses 2020 statement. Costs will be converted into a common currency (US dollar), and we will estimate the pooled cost and subgroup analysis will be done. The reference lists of included papers will be reviewed.

ETHICS AND DISSEMINATION

This systematic review will not involve human participants and requires no ethical approval. The results of this review will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023400215.

Association between light rare earth elements in maternal plasma and the risk of spontaneous preterm birth: a nested case-control study from the Beijing birth cohort study

BACKGROUND

Parental exposure to rare earth elements (REEs) could increase the risk of premature rupture of membranes, a major cause of spontaneous preterm birth (SPB). In addition, different subtypes of SPB, such as spontaneous preterm labor (SPL) and preterm premature rupture of membranes (PPROM), may have different susceptibility to environmental exposure. Therefore, we investigated the potential associations between REE exposure in different trimesters and SPB and its subtypes.

METHODS

A nested case-control study was performed. We included 244 women with SPB as cases and 244 women with full-term delivery as controls. The plasma concentrations of light REEs were measured in the first and third trimesters. Logistic regression was used to analyze the associations between single REE levels and SPB, and Bayesian kernel machine regression (BKMR) was used to analyze the mixed-exposure effect.

RESULTS

Exposure to light REEs was associated with SPB and its subtypes only in the third trimester. Specifically, the intermediate- and highest-tertile concentration groups of La and the highest-tertile concentration group of Sm were associated with an increased risk of SPL, with adjusted odds ratios (AORs) of 2.00 (95% CIs: 1.07-3.75), 1.87 (95% CIs: 1.01-3.44), and 1.82 (95% CIs: 1.00-3.30), respectively. The highest-tertile concentration group of Pr was associated with an increased risk of PPROM, with an AOR of 1.69 (95% CIs: 1.00-2.85). Similar results were also found in BKMR models.

CONCLUSIONS

La and Sm levels in plasma may be associated with the risk of SPL, and Pr levels in plasma may be associated with the risk of PPROM.

Adapting the preterm birth phenotyping framework to a low-resource, rural setting and applying it to births from Migori County in western Kenya

BACKGROUND

Preterm birth is the leading cause of neonatal and under-five mortality worldwide. It is a complex syndrome characterized by numerous etiologic pathways shaped by both maternal and fetal factors. To better understand preterm birth trends, the Global Alliance to Prevent Prematurity and Stillbirth published the preterm birth phenotyping framework in 2012 followed by an application of the model to a global dataset in 2015 by Barros, et al. Our objective was to adapt the preterm birth phenotyping framework to retrospective data from a low-resource, rural setting and then apply the adapted framework to a cohort of women from Migori, Kenya.

METHODS

This was a single centre, observational, retrospective chart review of eligible births from November 2015 - March 2017 at Migori County Referral Hospital. Adaptations were made to accommodate limited diagnostic capabilities and data accuracy concerns. Prevalence of the phenotyping conditions were calculated as well as odds of adverse outcomes.

RESULTS

Three hundred eighty-seven eligible births were included in our study. The largest phenotype group was none (no phenotype could be identified; 41.1%), followed by extrauterine infection (25.1%), and antepartum stillbirth (16.7%). Extrauterine infections included HIV (75.3%), urinary tract infections (24.7%), malaria (4.1%), syphilis (3.1%), and general infection (3.1%). Severe maternal condition was ranked fourth (15.6%) and included anaemia (69.5%), chronic respiratory distress (22.0%), chronic hypertension prior to pregnancy (5.1%), diabetes (3.4%), epilepsy (3.4%), and sickle cell disease (1.7%). Fetal anaemia cases were the most likely to transfer to the newborn unit (OR 5.1, 95% CI 0.8, 30.9) and fetal anomaly cases were the most likely to result in a pre-discharge mortality (OR 3.9, 95% CI 0.8, 19.2).

CONCLUSIONS

Using routine data sources allowed for a retrospective analysis of an existing dataset, requiring less time and fewer resources than a prospective study and demonstrating a feasible approach to preterm phenotyping for use in low-resource settings to inform local prevention strategies.

Development of prognostic model for preterm birth using machine learning in a population-based cohort of Western Australia births between 1980 and 2015

Preterm birth is a global public health problem with a significant burden on the individuals affected. The study aimed to extend current research on preterm birth prognostic model development by developing and internally validating models using machine learning classification algorithms and population-based routinely collected data in Western Australia. The longitudinal retrospective cohort study involved all births in Western Australia between 1980 and 2015, and the analytic sample contains 81,974 (8.6%) preterm births (< 37 weeks of gestation). Prediction models for preterm birth were developed using regularised logistic regression, decision trees, Random Forests, extreme gradient boosting, and multi-layer perceptron (MLP). Predictors included maternal socio-demographics and medical conditions, current and past pregnancy complications, and family history. Class weight was applied to handle imbalanced outcomes and stratified tenfold cross-validation was used to reduce overfitting. Close to half of the preterm births (49.1% at 5% FPR, 95% CI 48.9%,49.5%) were correctly classified by the best performing classifier (MLP) for all women when current pregnancy information was available. The sensitivity was boosted to 52.7% (95% CI 52.1%,53.3%) after including past obstetric history in a sub-population of births from multiparous women. Around half of the preterm birth can be identified antenatally at high specificity using population-based routinely collected maternal and pregnancy data. The performance of the prediction models depends on the available predictor pool that is individual and time specific.

Effect of Nutrition Interventions Before and/or During Early Pregnancy on Low Birth Weight in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

BACKGROUND

This review aimed at synthesizing evidence on the effectiveness of nutritional interventions that were carried out before and/or during early pregnancy versus the control groups on reducing the risk of low weight at birth in sub-Saharan Africa.

METHODS

We have searched on MEDLINE, SCOPUS, CINAHL, HINARI, and Cochrane Library of systematic review databases for published articles in English language from 2010 to 2021 years. For unpublished studies, we searched on Google scholar. Randomized controlled trial studies of nutritional interventions carried out before/or during early pregnancy in sub-Saharan Africa to improve low birth weight were considered. The data were extracted and pooled using the Joanna Briggs Institute software. The effect size was calculated using fixed-effect models. Mantel-Haenszel method was used to calculate the relative risk with their respective 95% CI. Heterogeneity was assessed using the standard chi-square and I ² tests.

RESULTS

Seven studies were included in the review with a total of 5934 participants. Three types of nutritional interventions were identified: iron supplementations, lipid-based supplementations, and nutritional education and counseling. We have identified only one intervention started during preconception. The meta-analysis showed that none of the identified nutrition interventions had a statistically significant effect on low birth weight.

CONCLUSIONS

Based on the review evidence, nutritional interventions before and/or during early pregnancy in sub-Saharan Africa had no significant effect on low birth weight. However, since our evidence was derived from a small number of trials and participants, a large-scale randomized controlled trials review might be required to elucidate the finding.

Development and reliability of the coding system evaluating maternal sensitivity to social interactions with 34- to 36-week postmenstrual age preterm infants

Maternal sensitivity (MS), the ability to perceive and synchronously respond to the social signals (SSs), is affected by prematurity. The development of early supportive psychotherapy to foster MS, before discharge of the infant from the neonatal intensive care unit (NICU) is a major challenge in the prevention of subsequent developmental and mental disorders in the child. There are currently no reliable methods for evaluating MS to social interactions with very to moderate preterm infants. We investigated the reliability of a newly developed procedure for assessing MS in interactions between the mother and her 34- to 36-week postmenstrual age (PMA) preterm infant: the Preterm Infant Coding System for Maternal Sensitivity (PRICOSMAS).

METHOD

This study encompassed three steps: testing of the capacity to videorecord SSs in very to moderate preterm infants, selection, by an expert committee, of the recordable and relevant SSs, and investigation of the internal consistency and interrater reliability. The synchronicity between infant and mother's SSs was determined on a 1 s period basis, using ELAN software. Preterm infants born after 25-weeks gestational age (GA) were included while being between 34- and 36-weeks PMA. A perinatal risk inventory score > 10 for the infant precluded from inclusion. Interrater reliabilities were assessed independently by two raters blind to the clinical situation of the mother and infant.

RESULTS

The resulting PRICOSMAS encompassed two four-item SS sections, one covering the preterm infant's SSs and the other, the mother's SSs. Reliability was assessed on a sample of 26 videorecorded observations for 13 mother-preterm infant dyads. Infants' mean age at birth was 30.4 ± 3.1-weeks GA (range: 26.4-35) and PMA at the time of the test was 34.7-weeks (±0.8). Internal consistency ranged from 0.81 to 0.89. Interrater reliability ranged from substantial to almost perfect (0.73-0.88).

CONCLUSION

This study shows that the infants' SSs and MS can be reliably scored in preterm infants as young as 34- to 36-weeks PMA. Our findings suggest that the PRICOSMAS is sufficiently reliable for use, including in NICU, by healthcare professionals or researchers for coding early parent-infant interactions with 34- to 36-week PMA preterm infants.

Prevalence and risk factors associated with birth asphyxia among neonates delivered in Ethiopia: A systematic review and meta-analysis

BACKGROUND

A number of primary studies in Ethiopia address the prevalence of birth asphyxia and the factors associated with it. However, variations were seen among those studies. The main aim of this systematic review and meta-analysis was carried out to estimate the pooled prevalence and explore the factors that contribute to birth asphyxia in Ethiopia.

METHODS

Different search engines were used to search online databases. The databases include PubMed, HINARI, Cochrane Library and Google Scholar. Relevant grey literature was obtained through online searches. The funnel plot and Egger's regression test were used to see publication bias, and the I-squared was applied to check the heterogeneity of the studies. Cross-sectional, case-control and cohort studies that were conducted in Ethiopia were also be included. The Joanna Briggs Institute checklist was used to assess the quality of the studies and was included in this systematic review. Data entry and statistical analysis were carried out using RevMan 5.4 software and Stata 14.

RESULT

After reviewing 1,125 studies, 26 studies fulfilling the inclusion criteria were included in the meta-analysis. The pooled prevalence of birth asphyxia in Ethiopia was 19.3%. In the Ethiopian context, the following risk factors were identified: Antepartum hemorrhage(OR: 4.7; 95% CI: 3.5, 6.1), premature rupture of membrane(OR: 4.0; 95% CI: 12.4, 6.6), primiparas(OR: 2.8; 95% CI: 1.9, 4.1), prolonged labor(OR: 4.2; 95% CI: 2.8, 6.6), maternal anaemia(OR: 5.1; 95% CI: 2.59, 9.94), low birth weight(OR = 5.6; 95%CI: 4.7,6.7), meconium stained amniotic fluid(OR: 5.6; 95% CI: 4.1, 7.5), abnormal presentation(OR = 5.7; 95% CI: 3.8, 8.3), preterm birth(OR = 4.1; 95% CI: 2.9, 5.8), residing in a rural area (OR: 2.7; 95% CI: 2.0, 3.5), caesarean delivery(OR = 4.4; 95% CI:3.1, 6.2), operative vaginal delivery(OR: 4.9; 95% CI: 3.5, 6.7), preeclampsia(OR = 3.9; 95% CI: 2.1, 7.4), tight nuchal cord OR: 3.43; 95% CI: 2.1, 5.6), chronic hypertension(OR = 2.5; 95% CI: 1.7, 3.8), and unable to write and read (OR = 4.2;95%CI: 1.7, 10.6).

CONCLUSION

According to the findings of this study, birth asphyxia is an unresolved public health problem in the Ethiopia. Therefore, the concerned body needs to pay attention to the above risk factors in order to decrease the country's birth asphyxia.

REVIEW REGISTRATION

PROSPERO International prospective register of systematic reviews (CRD42020165283).

Association Between Preterm-Birth Phenotypes and Differential Morbidity, Growth, and Neurodevelopment at Age 2 Years: Results From the INTERBIO-21st Newborn Study

IMPORTANCE

The etiologic complexities of preterm birth remain inadequately understood, which may impede the development of better preventative and treatment measures.

OBJECTIVE

To examine the association between specific preterm-birth phenotypes and clinical, growth, and neurodevelopmental differences among preterm newborns compared with term newborns up to age 2 years.

DESIGN, SETTING, AND PARTICIPANTS

The INTERBIO-21st study included a cohort of preterm and term newborn singletons enrolled between March 2012 and June 2018 from maternity hospitals in 6 countries worldwide who were followed up from birth to age 2 years. All pregnancies were dated by ultrasonography. Data were analyzed from November 2019 to October 2020.

EXPOSURES/INTERVENTIONS

Preterm-birth phenotypes.

MAIN OUTCOMES AND MEASURES

Infant size, health, nutrition, and World Health Organization motor development milestones assessed at ages 1 and 2 years; neurodevelopment evaluated at age 2 years using the INTERGROWTH-21st Neurodevelopment Assessment (INTER-NDA) tool.

RESULTS

A total of 6529 infants (3312 boys [50.7%]) were included in the analysis. Of those, 1381 were preterm births (mean [SD] gestational age at birth, 34.4 [0.1] weeks; 5148 were term births (mean [SD] gestational age at birth, 39.4 [0] weeks). Among 1381 preterm newborns, 8 phenotypes were identified: no main maternal, fetal, or placental condition detected (485 infants [35.1%]); infections (289 infants [20.9%]); preeclampsia (162 infants [11.7%]); fetal distress (131 infants [9.5%]); intrauterine growth restriction (110 infants [8.0%]); severe maternal disease (85 infants [6.2%]); bleeding (71 infants [5.1%]); and congenital anomaly (48 infants [3.5%]). For all phenotypes, a previous preterm birth was a risk factor for recurrence. Each phenotype displayed differences in neonatal morbidity and infant outcomes. For example, infants with the no main condition detected phenotype had low neonatal morbidity but increased morbidity and hospitalization incidence at age 1 year (odds ratio [OR], 2.2; 95% CI, 1.8-2.7). Compared with term newborns, the highest risk of scoring lower than the 10th centile of INTER-NDA normative values was observed in the fine motor development domain among newborns with the fetal distress (OR, 10.6; 95% CI, 5.1-22.2) phenotype.

CONCLUSIONS AND RELEVANCE

Results of this study suggest that phenotypic classification may provide a better understanding of the etiologic factors and mechanisms associated with preterm birth than continuing to consider it an exclusively time-based entity.

Phenotypic Classification of Preterm Birth Among Nulliparous Women: A Population-Based Cohort Study

OBJECTIVE

A classification model based on preterm birth clinical presentations (phenotypes) was proposed at the International Conference on Prematurity and Stillbirth, with calls for validation. This study sought to determine the distribution of clinical phenotypes of preterm birth among nulliparous women, their corresponding associations with maternal characteristics, and the odds ratios (ORs) of preterm Caesarean section and other adverse outcomes.

METHODS

A population-based cohort study was performed of all nulliparous women with singleton pregnancies (>20 weeks) who gave birth in a hospital in Ontario between 2012 and 2014. Logistic regression models were used to estimate adjusted ORs (Canadian Task Force Classification II-2).

RESULTS

Among 113 942 nulliparous women, 6.1% delivered at <37 weeks, at a mean gestational age of 33.9 weeks. Of those women, 34.1% did not meet the criteria for the presence of any clinical phenotype; 42.3% had one maternal, fetal, or placental condition; 22.3% had two clinical conditions; and 1.3% had three clinical conditions. The most common preterm birth phenotypes were worsening of maternal diseases (24.0%), intrauterine growth restriction (23.5%), and fetal distress (23.0%). Compared with preterm births without any significant clinical phenotype, those with maternal, fetal, or placental phenotypes were associated with increased odds of Caesarean section (adjusted ORs 2.70 [95% confidence interval [CI] 2.30-3.17], 1.66 [95% CI 1.36-2.03], and 6.49 [95% CI 4.29-9.80], respectively).

CONCLUSION

Approximately two thirds of nulliparous preterm births were grouped into distinct clinical phenotypes. This study demonstrated that outcomes varied across phenotypes, thus providing evidence of benefit for the phenotypic classification model.

Deep clinical and biological phenotyping of the preterm birth and small for gestational age syndromes: The INTERBIO-21 st Newborn Case-Control Study protocol

Background: INTERBIO-21 ^st is Phase II of the INTERGROWTH-21 ^st Project, the population-based, research initiative involving nearly 70,000 mothers and babies worldwide coordinated by Oxford University and performed by a multidisciplinary network of more than 400 healthcare professionals and scientists from 35 institutions in 21 countries worldwide. Phase I, conducted 2008-2015, consisted of nine complementary studies designed to describe optimal human growth and neurodevelopment, based conceptually on the WHO prescriptive approach. The studies generated a set of international standards for monitoring growth and neurodevelopment, which complement the existing WHO Child Growth Standards. Phase II aims to improve the functional classification of the highly heterogenous preterm birth and fetal growth restriction syndromes through a better understanding of how environmental exposures, clinical conditions and nutrition influence patterns of human growth from conception to childhood, as well as specific neurodevelopmental domains and associated behaviors at 2 years of age.

Methods: In the INTERBIO-21 ^st Newborn Case-Control Study, a major component of Phase II, our objective is to investigate the mechanisms potentially responsible for preterm birth and small for gestational age and their interactions, using deep phenotyping of clinical, growth and epidemiological data and associated nutritional, biochemical, omic and histological profiles. Here we describe the study sites, population characteristics, study design, methodology and standardization procedures for the collection of longitudinal clinical data and biological samples (maternal blood, umbilical cord blood, placental tissue, maternal feces and infant buccal swabs) for the study that was conducted between 2012 and 2018 in Brazil, Kenya, Pakistan, South Africa, Thailand and the UK.

Discussion: Our study provides a unique resource for the planned analyses given the range of potentially disadvantageous exposures (including poor nutrition, pregnancy complications and infections) in geographically diverse populations worldwide. The study should enhance current medical knowledge and provide new insights into environmental influences on human growth and neurodevelopment.

Deep clinical and biological phenotyping of the preterm birth and small for gestational age syndromes: The INTERBIO-21 st Newborn Case-Control Study protocol

Background: INTERBIO-21 ^st is Phase II of the INTERGROWTH-21 ^st Project, the population-based, research initiative involving nearly 70,000 mothers and babies worldwide coordinated by Oxford University and performed by a multidisciplinary network of more than 400 healthcare professionals and scientists from 35 institutions in 21 countries worldwide. Phase I, conducted 2008-2015, consisted of nine complementary studies designed to describe optimal human growth and neurodevelopment, based conceptually on the WHO prescriptive approach. The studies generated a set of international standards for monitoring growth and neurodevelopment, which complement the existing WHO Child Growth Standards. Phase II aims to improve the functional classification of the highly heterogenous preterm birth and fetal growth restriction syndromes through a better understanding of how environmental exposures, clinical conditions and nutrition influence patterns of human growth from conception to childhood, as well as specific neurodevelopmental domains and associated behaviors at 2 years of age. Methods: In the INTERBIO-21 ^st Newborn Case-Control Study, a major component of Phase II, our objective is to investigate the mechanisms potentially responsible for preterm birth and small for gestational age and their interactions, using deep phenotyping of clinical, growth and epidemiological data and associated nutritional, biochemical, omic and histological profiles. Here we describe the study sites, population characteristics, study design, methodology and standardization procedures for the collection of longitudinal clinical data and biological samples (maternal blood, umbilical cord blood, placental tissue, maternal feces and infant buccal swabs) for the study that was conducted between 2012 and 2018 in Brazil, Kenya, Pakistan, South Africa, Thailand and the UK. Discussion: Our study provides a unique resource for the planned analyses given the range of potentially disadvantageous exposures (including poor nutrition, pregnancy complications and infections) in geographically diverse populations worldwide. The study should enhance current medical knowledge and provide new insights into environmental influences on human growth and neurodevelopment.

Validation of maternal reports for low birthweight and preterm birth indicators in rural Nepal

Background

Tracking progress towards global newborn health targets depends largely on maternal reported data collected through large, nationally representative surveys. We evaluated the validity, across a range of recall period lengths (1 to 24 months post-delivery), of maternal report of birthweight, birth size and length of pregnancy.

Methods

We compared maternal reports to reference standards of birthweights measured within 72 hours of delivery and gestational age generated from reported first day of the last menstrual period (LMP) prospectively collected as part of a population-based study (n = 1502). We calculated sensitivity, specificity, area the under the receiver operating curve (AUC) as a measure of individual-level accuracy, and the inflation factor (IF) to quantify population-level bias for each indicator. We assessed if length of recall period modified accuracy by stratifying measurements across time bins and using a modified Poisson regression with robust error variance to estimate the relative risk (RR) of correctly classifying newborns as low birthweight (LBW) or preterm, adjusting for child sex, place of delivery, maternal age, maternal education, parity, and ethnicity.

Results

The LBW indicator using maternally reported birthweight in grams had low individual-level accuracy (AUC = 0.69) and high population-level bias (inflation factor IF = 0.62). LBW using maternally reported birth size and the preterm birth indicator had lower individual-level accuracy (AUC = 0.58 and 0.56, respectively) and higher population-level bias (IF = 0.28 and 0.35, respectively) up to 24 months following birth. Length of recall time did not affect accuracy of LBW indicators. For the preterm birth indicator, accuracy did not change with length of recall up to 20 months after birth and improved slightly beyond 20 months.

Conclusions

The use of maternal reports may underestimate and bias indicators for LBW and preterm birth. In settings with high prevalence of LBW and preterm births, these indicators generated from maternal reports may be more vulnerable to misclassification. In populations where an important proportion of births occur at home or where weight is not routinely measured, mothers perhaps place less importance on remembering size at birth. Further work is needed to explore whether these conclusions on the validity of maternal reports hold in similar rural and low-income settings.

Perinatal stress moderates the link between early and later emotional skills in very preterm-born children: An 11-year-long longitudinal study

BACKGROUND

Very preterm (VPT) birth refers to an early stressful event putting children at heightened risk for emotional difficulties. However, there is an important individual variability, leaving unexplained why some VPT children do not develop emotional difficulties, while others develop such difficulties in the early years or later in life.

AIM

In this study, we examined whether perinatal stress is a risk factor explaining heterogeneities in emotional problems in VPT children.

METHODS

Thirty-six VPT children and 22 full-term born (FT) children participated in an 11 year-long study. Risk for perinatal stress was assessed at birth with the Perinatal Risk Inventory. Mothers reported children's emotional difficulties at 18 months of child age on the Symptom Checklist and at 11 years on the Child Behavior Checklist.

RESULTS

Results indicated significant differences in emotional scores at 11 years not only between VPT and FT children but also between the low and high perinatal stress groups. More importantly, emotional scores at 18 months influenced variability in internalizing scores at 11 years only in VPT children with high perinatal stress.

CONCLUSION

Although prematurity affects the emotional abilities of preadolescents, the link between emotional skills in early and later childhood is moderated by the severity of perinatal stress. In particular, VPT children who are born with more complications, and as such experience a more stressful perinatal environment, are more likely to show emotional difficulties at preadolescence.

Risk of recurrent spontaneous preterm birth: a systematic review and meta-analysis

OBJECTIVE

To determine the risk of recurrent spontaneous preterm birth (sPTB) following sPTB in singleton pregnancies.

DESIGN

Systematic review and meta-analysis using random effects models.

DATA SOURCES

An electronic literature search was conducted in OVID Medline (1948-2017), Embase (1980-2017) and ClinicalTrials.gov (completed studies effective 2017), supplemented by hand-searching bibliographies of included studies, to find all studies with original data concerning recurrent sPTB.

STUDY ELIGIBILITY CRITERIA

Studies had to include women with at least one spontaneous preterm singleton live birth (<37 weeks) and at least one subsequent pregnancy resulting in a singleton live birth. The Newcastle-Ottawa Scale was used to assess study quality.

RESULTS

Overall, 32 articles involving 55 197 women, met all inclusion criteria. Generally studies were well conducted and had a low risk of bias. The absolute risk of recurrent sPTB at <37 weeks' gestation was 30% (95% CI 27% to 34%). The risk of recurrence due to preterm premature rupture of membranes (PPROM) at <37 weeks gestation was 7% (95% CI 6% to 9%), while the risk of recurrence due to preterm labour (PTL) at <37 weeks gestation was 23% (95% CI 13% to 33%).

CONCLUSIONS

The risk of recurrent sPTB is high and is influenced by the underlying clinical pathway leading to the birth. This information is important for clinicians when discussing the recurrence risk of sPTB with their patients.

Preterm birth trend in Taiwan from 2001 to 2009

AIM

The aim of this study was to analyze the trends and risk factors of preterm birth from all the women who delivered during 2001-2009 in Taiwan.

MATERIAL AND METHODS

We analyzed the preterm birth rates, the proportions of obstetric antecedents and risk factors in the population of pregnant women and neonatal Apgar scores according to the National Medical Birth Register database from 2001 to 2009. Adjusted odds ratios (OR) with 95% confidence intervals for risk factors of preterm birth were assessed using multivariable logistic regression models. The obstetric antecedents of preterm birth for singletons were stratified by spontaneous preterm labor and indicated preterm delivery (labor induction or elective cesarean delivery).

RESULTS

The preterm birth rate was 8.56% with the majority (89.76%) delivered between 32 and 37 weeks of gestation. A 0.07% annual increase (P < 0.001) in preterm delivery was observed. The greatest risk factors were multiple pregnancies (OR > 20), followed by medical complications (OR > 2.8), congenital malformations (OR > 2), teen pregnancies (OR > 1), and advanced maternal age (OR > 1). Specifically, singleton preterm births comprised 57.3% spontaneous labor and 42.7% indicated delivery. There was a 0.5% annual increase (P < 0.001) in indicated delivery. Incidence of neonates with poor Apgar scores (<7) was significantly different between those with and without medical complications (P < 0.001).

CONCLUSIONS

The preterm birth rate increased significantly from 2001 to 2009 and multiple pregnancies were the most important contributing factor. Most of the singleton preterm births resulted from spontaneous labor, but the proportion of indicated deliveries increased.

Association of maternal hypertension and chorioamnionitis with preterm outcomes

OBJECTIVES

We compared the relative effect of hypertensive disorders of pregnancy and chorioamnionitis on adverse neonatal outcomes in very preterm neonates, and studied whether gestational age (GA) modulates these effects.

METHODS

A cohort of neonates 23 to 30 weeks' GA, born in 2008 to 2011 in 82 hospitals adhering to the Italian Neonatal Network, was analyzed. Infants born from mothers who had hypertensive disorders (N = 2096) were compared with those born after chorioamnionitis (N = 1510). Statistical analysis employed logistic models, adjusting for GA, hospital, and potential confounders.

RESULTS

Overall mortality was higher after hypertension than after chorioamnionitis (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.08-1.80), but this relationship changed across GA weeks; the OR for hypertension was highest at low GA, whereas from 28 weeks' GA onward, mortality was higher for chorioamnionitis. For other outcomes, the relative risks were constant across GA; infants born after hypertension had an increased risk for bronchopulmonary dysplasia (OR, 2.20; 95% CI, 1.68-2.88) and severe retinopathy of prematurity (OR, 1.48; 95% CI, 1.02-2.15), whereas there was a lower risk for early-onset sepsis (OR, 0.25; 95% CI, 0.19-0.34), severe intraventricular hemorrhage (OR, 0.65; 95% CI, 0.48-0.88), periventricular leukomalacia (OR, 0.70; 95% CI, 0.48-1.01), and surgical necrotizing enterocolitis or gastrointestinal perforation (OR, 0.47; 95% CI, 0.31-0.72).

CONCLUSIONS

Mortality and other adverse outcomes in very preterm infants depend on antecedents of preterm birth. Hypertension and chorioamnionitis are associated with different patterns of outcomes; for mortality, the effect changes across GA weeks.

Pregnancy disorders leading to very preterm birth influence neonatal outcomes: results of the population-based ACTION cohort study

BACKGROUND

We examined the relationships between -pregnancy disorders leading to very preterm birth -(spontaneous preterm labor, prelabor premature rupture of -membranes (PPROM), hypertension/preeclampsia, -intrauterine growth restriction (IUGR), antenatal hemorrhage, and maternal -infection), both in isolation and grouped together as -"disorders of placentation" (hypertensive disorders and IUGR) vs. -"presumed infection/inflammation" (all the others), and several unfavorable neonatal outcomes.

METHODS

We examined a population-based prospective cohort of 2,085 singleton infants of 23-31 wk gestational age (GA) born in six Italian regions (the Accesso alle Cure e Terapie Intensive Ostetriche e Neonatali (ACTION) study).

RESULTS

Neonates born following disorders of placentation had a higher GA and better overall outcomes than those born following infection/inflammation. After adjustment for GA, however, they showed higher risk of mortality (odds ratio, OR: 1.4; 95% confidence interval, CI: 1.0-2.0), bronchopulmonary dysplasia (BPD) (OR: 2.5; CI: 1.8-3.6), and retinopathy of prematurity (ROP) (OR: 2.0; CI: 1.1-3.5), especially in growth-restricted infants, and a lower risk of intraventricular hemorrhage (IVH) (OR: 0.5; CI: 0.3-0.8) and periventricular leukomalacia (PVL) (OR: 0.6; CI: 0.4-1.1) as compared with infants born following -infection/inflammation disorders.

CONCLUSION

Our data confirm the hypothesis that, in very preterm infants, adverse outcomes are both a function of immaturity (low GA) and of complications leading to preterm birth. The profile of risk is different in different pregnancy disorders.

Statistical considerations for the development of prescriptive fetal and newborn growth standards in the INTERGROWTH-21st Project

The INTERGROWTH-21(st) Project has in its mandate to develop prescriptive standards for fetal, neonatal and preterm post-neonatal growth. The project comprises three components: the Fetal Growth Longitudinal Study (FGLS), the Preterm Postnatal Follow-up Study (PPFS), and the Newborn Cross-Sectional Study (NCSS). We consider here the statistical aspects of the three components as they relate to the construction of these standards, in particular the sample size, and outline the principles that will guide the planned main analyses.

Changes in risk factors for preterm birth in Western Australia 1984-2006

OBJECTIVE

To characterise changing risk factors of preterm birth in Western Australia between 1984 and 2006.

DESIGN

Population-based study.

SETTING

Western Australia.

POPULATION

All non-Aboriginal women giving birth to live singleton infants between 1984 and 2006.

METHODS

Multinomial, multivariable regression models were used to assess antecedent profiles by preterm status and labour onset types (spontaneous, medically indicated, prelabour rupture of membranes [PROM]). Population attributable fraction (PAF) estimates characterized the contribution of individual antecedents as well as the overall contribution of two antecedent groups: pre-existing medical conditions (including previous obstetric history) and pregnancy complications.

MAIN OUTCOME MEASURE

Antecedent relationships with preterm birth, stratified by labour onset type.

RESULTS

Marked increases in maternal age and primiparous births were observed. A four-fold increase in the rates of pre-existing medical complications over time was observed. Rates of pregnancy complications remained stable. Multinomial regression showed differences in antecedent profiles across labour onset types. PAF estimates indicated that 50% of medically indicated preterm deliveries could be eliminated after removing six antecedents from the population; estimates for PROM and spontaneous preterm reduction were between 10 and 20%. Variables pertaining to previous and current obstetric complications (previous preterm birth, previous caesarean section, pre-eclampsia and antepartum haemorrhage) were the most influential predictors of preterm birth and adverse labour onset (PROM and medically indicated).

CONCLUSIONS

Preterm antecedent profiles have changed markedly over the 23 years studied. Some changes may be attributable to true change, others to advances in surveillance and detection. Still others may signify change in clinical practice.

Subtypes of preterm birth and the risk of postneonatal death

OBJECTIVE

To examine the differences in postneonatal death risk among 3 clinical subtypes of preterm birth: preterm premature rupture of membranes (PROM), indicated preterm birth, and spontaneous preterm labor.

STUDY DESIGN

We analyzed the 2001-2005 US linked birth/infant death (birth cohort) datasets. The preterm birth subtypes were classified using information on the birth certificate: reported PROM, induction of labor, cesarean section, and complications of pregnancy and labor. Cox proportional hazard models were used to estimate covariate-adjusted hazard ratios and 95% CIs for postneonatal death (from days 28 to 365). Estimation was given for preterm birth subtypes in a week-by-week analysis. Causes of death were analyzed by preterm birth subtype and then separately at 24-27, 28-31, and 32-36 weeks of gestation.

RESULTS

For the total of 1895350 singleton preterm births who survived the neonatal period, the postneonatal mortality rate was 1.11% for preterm PROM, 0.78% for indicated preterm birth, and 0.53% for spontaneous preterm labor. Preterm PROM was associated with significantly higher risk of postneonatal death compared with spontaneous preterm labor in infants born at 27 weeks gestation or later. Similarly, indicated preterm birth was associated with a significantly higher risk of postneonatal death than spontaneous preterm labor in infants born at 25 weeks gestation or later. Preterm PROM and indicated preterm birth were associated with greater risk of death in the postneonatal period compared with spontaneous preterm labor, irrespective of the cause of death.

CONCLUSION

Subtypes of preterm birth carry different risks of postneonatal mortality. Prevention of preterm-related postneonatal death may require more research into the root causes of preterm birth subtypes.

First-trimester prediction of preterm birth using ADAM12, PAPP-A, uterine artery Doppler, and maternal characteristics

OBJECTIVE

The objective of this study was to estimate the efficiency of first-trimester a disintegrin and metalloprotease 12 (ADAM12), pregnancy-associated plasma protein A (PAPP-A), uterine artery Doppler, and maternal characteristics in the prediction of preterm birth (PTB).

METHODS

This was a prospective cohort study of patients presenting for first-trimester aneuploidy screening. Maternal serum ADAM12 and PAPP-A levels were measured by immunoassay, and mean uterine artery Doppler pulsatility indices were calculated. The primary outcome was PTB <34 weeks' gestation, and the secondary outcome was PTB <37 weeks' gestation. Logistic regression was used to model the prediction of PTB using ADAM12, PAPP-A, uterine artery Doppler, and maternal characteristics, individually and in combination. Sensitivity, specificity, and area under the receiver-operating characteristic curves were compared between models.

RESULTS

Of 578 patients, 36 (6.2%) delivered <34 weeks, and 78 (13.5%) delivered <37 weeks. For a 20% fixed false positive rate, ADAM12, PAPP-A, and uterine artery Doppler identified 58%, 52%, and 62% of patients with PTB <34 weeks and 42%, 48%, and 50% of patients with PTB <37 weeks, respectively. Combining these first-trimester parameters did not improve the predictive efficiency of the models.

CONCLUSION

First-trimester ADAM12, PAPP-A, and uterine artery Doppler are each modestly predictive of PTB; however, combinations of these parameters do not further improve their screening efficiency.

The preterm birth syndrome: a prototype phenotypic classification

Preterm birth is a syndrome with many causes and phenotypes. We propose a classification that is based on clinical phenotypes that are defined by ≥ 1 characteristics of the mother, the fetus, the placenta, the signs of parturition, and the pathway to delivery. Risk factors and mode of delivery are not included. There are 5 components in a preterm birth phenotype: (1) maternal conditions that are present before presentation for delivery, (2) fetal conditions that are present before presentation for delivery, (3) placental pathologic conditions, (4) signs of the initiation of parturition, and (5) the pathway to delivery. This system does not force any preterm birth into a predefined phenotype and allows all relevant conditions to become part of the phenotype. Needed data can be collected from the medical records to classify every preterm birth. The classification system will improve understanding of the cause and improve surveillance across populations.

Perinatal morbidity associated with late preterm deliveries compared with deliveries between 37 and 40 weeks of gestation

OBJECTIVE

To estimate the risk of short-term complications in neonates born between 34 and 36 weeks of gestation.

DESIGN

This is a retrospective cohort study.

SETTING

Deliveries in 2005 in the USA.

POPULATION

Singleton live births between 34 and 40 weeks of gestation.

METHODS

Gestational age was subgrouped into 34, 35, 36 and 37-40 completed weeks of gestation. Statistical comparisons were performed using chi-square test and multivariable logistic regression models, with 37-40 weeks of gestation designated as referent.

MAIN OUTCOME MEASURES

Perinatal morbidities, including 5-minute Apgar scores, hyaline membrane disease, neonatal sepsis/antibiotics use, and admission to the intensive care unit.

RESULTS

In all, 175,112 neonates were born between 34 and 36 weeks in 2005. Compared with neonates born between 37 and 40 weeks, neonates born at 34 weeks had higher odds of 5-minute Apgar <7 (adjusted odds ratio [aOR] 5.51, 95% CI 5.16-5.88), hyaline membrane disease (aOR 10.2, 95% CI 9.44-10.9), mechanical ventilation use >6 hours (aOR 9.78, 95% CI 8.99-10.6) and antibiotic use (aOR 9.00, 95% CI 8.43-9.60). Neonates born at 35 weeks were similarly at risk of morbidity, with higher odds of 5-minute Apgar <7 (aOR 3.42, 95% CI 3.23-3.63), surfactant use (aOR 3.74, 95% CI 3.21-4.22), ventilation use >6 hours (aOR 5.53, 95% CI 5.11-5.99) and neonatal intensive-care unit admission (aOR 11.3, 95% CI 11.0-11.7). Neonates born at 36 weeks remain at higher risk of morbidity compared with deliveries at 37-40 weeks of gestation.

CONCLUSIONS

Although the risk of undesirable neonatal outcomes decreases with increasing gestational age, the risk of neonatal complications in late preterm births remains higher compared with infants delivered at 37-40 weeks of gestation.

Singleton preterm births in korle bu teaching hospital, accra, ghana - origins and outcomes

SUMMARY OBJECTIVE

To determine the singleton preterm birth rate, the relative proportions of the clinical categories of preterm births and to compare the outcomes in these categories.

SETTING

Department of Obstetrics & Gynaecology, Korle Bu Teaching Hospital.

PARTICIPANTS

Preterm births from 1(st) July to 31(st) December 2003.

RESULTS

Out of a total of 4731 singleton births 440 were preterm, giving a preterm birth rate of 9.3%. One hundred and eighty-five (42%, [95% Confidence Interval (CI) 37.4%, 46.8%]) preterm births followed spontaneous onset of preterm labour (group A), 82 (18.6%, [95% CI 15.2%, 22.7%]) followed preterm premature rupture of membranes, PPROM (group B) and 173 (39.3%, [95% CI 34.8%, 44.1%]) were medically indicated (group C). The commonest indication for delivery in group C was severe pre-eclampsia/eclampsia. Although there was no significant difference in the mean gestational ages at delivery between the groups, babies in group C had significantly lower birth weights. No differences in sex ratios, still-birth rates, or incidence of low Apgar scores were found. Babies in group C were significantly more likely to be admitted to the neonatal intensive care unit (NICU) and had a significantly higher perinatal death rate. Survivors of NICU admission among group C babies spent significantly longer periods in hospital before discharge.

CONCLUSION

Outcomes of preterm births in Korle Bu Teaching Hospital are less favourable among indicated preterm births than among spontaneous or PPROM-related preterm births. A detailed study of the causes of neonatal morbidity and mortality is suggested to determine any differences between the three groups.

Preventing preterm birth and neonatal mortality: exploring the epidemiology, causes, and interventions

Globally, each year, an estimated 13 million infants are born before 37 completed weeks of gestation. Complications from these preterm births are the leading cause of neonatal mortality. Preterm birth is directly responsible for an estimated one million neonatal deaths annually and is also an important contributor to child and adult morbidities. Low- and middle-income countries are disproportionately affected by preterm birth and carry a greater burden of disease attributed to preterm birth. Causes of preterm birth are multifactorial, vary by gestational age, and likely vary by geographic and ethnic contexts. Although many interventions have been evaluated, few have moderate-to high-quality evidence for decreasing preterm birth: smoking cessation and progesterone treatment in women with a high risk of preterm birth in low- and middle-income countries and cervical cerclage for those in high-income countries. Antepartum and postnatal interventions (eg, antepartum maternal steroid administration, or kangaroo mother care) to improve preterm neonatal survival after birth have been demonstrated to be effective but have not been widely implemented. Further research efforts are urgently needed to better understand context-specific pathways leading to preterm birth; to develop appropriate, efficacious prevention strategies and interventions to improve survival of neonates born prematurely; and to scale-up known efficacious interventions to improve the health of the preterm neonate.

Mortality risk among preterm babies: immaturity versus underlying pathology

BACKGROUND

Deaths among preterm births are presumably due to both immaturity and the conditions that cause preterm birth. Their relative contributions are unknown.

METHODS

Using US birth certificates (1995-2002), we estimated what portion of preterm neonatal mortality may be attributable to immaturity alone. Twins have elevated mortality, yet they usually have lower mortality than singletons at most preterm weeks. Twinning itself is a cause of early birth. Thus, at any given preterm week, singletons are more likely than twins to have pathologic causes of preterm delivery. If any such cause is associated with a mortality risk higher than that conferred by twinning, it is possible for singletons to have higher mortality than twins at some preterm weeks. Thus, mortality of twins at those weeks comes closer to describing the risk due to immaturity itself. To exclude high-risk babies, we focused on singletons and twins least likely to have suffered fetal growth disruptions (ie, those with "optimal" birth weight). At each gestational week from 24 to 36, we identified (for twins and singletons separately) the 500-gram weight category with the lowest neonatal mortality, and selected the lower of the 2 mortality rates.

RESULTS

Using the above as our best estimates of mortality due to immaturity alone, we calculated that about half the mortality of singleton preterm babies was due to the pathologies that cause early delivery.

CONCLUSIONS

Factors that cause preterm birth apparently contribute a large proportion of preterm mortality. If so, the prevention of preterm mortality requires more than the postponement of delivery.

The role of progesterone in prevention of preterm birth

Preterm birth continues to provide an enormous challenge in the delivery of perinatal health care, and is associated with considerable short and long-term health consequences for surviving infants. Progesterone has a role in maintaining pregnancy, by suppression of the calcium-calmodulin-myosin light chain kinase system. Additionally, progesterone has recognized anti-inflammatory properties, raising a possible link between inflammatory processes, alterations in progesterone receptor expression and the onset of preterm labor. Systematic reviews of randomized controlled trials evaluating the use of intramuscular and vaginal progesterone in women considered to be at increased risk of preterm birth have been published, with primary outcomes of perinatal death, preterm birth <34 weeks, and neurodevelopmental handicap in childhood. Eleven randomized controlled trials were included in the systematic review, involving 2714 women and 3452 infants, with results presented according to the reason women were considered to be at increased risk of preterm birth. While there is a potential beneficial effect in the use of progesterone for some women considered to be at increased risk of preterm birth, primarily in the reduction in the risk of preterm birth before 34 weeks gestation, it remains unclear if the observed prolongation of pregnancy translates into improved health outcomes for the infant.

The role of cervical length measurement at 11-14 weeks for the prediction of preterm delivery

OBJECTIVE

To determine whether cervical length (CL) measurement at 11?14 weeks is predictive of preterm delivery (PTD).

METHODS

This was a prospective study of a low-risk population of 1113 women, who underwent CL measurement at 11-14 weeks. Mean CL was calculated for deliveries at >37, <37 and <34 weeks. Cut-off limits of 27 mm and 30 mm were used to examine the predictive value of CL.

RESULTS

Mean +/- SD CL for the entire study population was 40.6 +/- 5.5 mm. CL was analyzed for term and PTD (<37 weeks) and further analyzed for deliveries at 34-37 and <34 weeks. Mean CL was 38.9 +/- 5.5 mm for PTD and 40.8 +/- 5.5 mm for deliveries >37 weeks (p=0.001). Receiver operating characteristic analysis showed small predictive value of CL for PTD <37 weeks (sensitivity = 63.3% and specificity = 51.1%, area under the curve (AUC)=0.60, 95% CI: 0.54-0.66) (p=0.001) and did not show any predictive value for PTD <35 weeks (AUC=0.55, 95% CI: 0.43-0.67, p=0.355) or PTD <32 weeks (AUC=0.51, 95% CI: 0.30-0.74, p=0.851).

CONCLUSION

CL at 11-14 weeks does not appear to be predictive of PTD. Statistical analysis of CL did not show any predictive value for PTD <35 weeks, or <32 weeks and although it showed a predictive value for PTD at <37 weeks, the sensitivity was very low.

Global report on preterm birth and stillbirth (2 of 7): discovery science

Background

Normal and abnormal processes of pregnancy and childbirth are poorly understood. This second article in a global report explains what is known about the etiologies of preterm births and stillbirths and identifies critical gaps in knowledge. Two important concepts emerge: the continuum of pregnancy, beginning at implantation and ending with uterine involution following birth; and the multifactorial etiologies of preterm birth and stillbirth. Improved tools and data will enable discovery scientists to identify causal pathways and cost-effective interventions.

Pregnancy and parturition continuum

The biological process of pregnancy and childbirth begins with implantation and, after birth, ends with the return of the uterus to its previous state. The majority of pregnancy is characterized by rapid uterine and fetal growth without contractions. Yet most research has addressed only uterine stimulation (labor) that accounts for <0.5% of pregnancy.

Etiologies

The etiologies of preterm birth and stillbirth differ by gestational age, genetics, and environmental factors. Approximately 30% of all preterm births are indicated for either maternal or fetal complications, such as maternal illness or fetal growth restriction. Commonly recognized pathways leading to preterm birth occur most often during the gestational ages indicated: (1) inflammation caused by infection (22-32 weeks); (2) decidual hemorrhage caused by uteroplacental thrombosis (early or late preterm birth); (3) stress (32-36 weeks); and (4) uterine overdistention, often caused by multiple fetuses (32-36 weeks). Other contributors include cervical insufficiency, smoking, and systemic infections. Many stillbirths have similar causes and mechanisms. About two-thirds of late fetal deaths occur during the antepartum period; the other third occur during childbirth. Intrapartum asphyxia is a leading cause of stillbirths in low- and middle-income countries.

Recommendations

Utilizing new systems biology tools, opportunities now exist for researchers to investigate various pathways important to normal and abnormal pregnancies. Improved access to quality data and biological specimens are critical to advancing discovery science. Phenotypes, standardized definitions, and uniform criteria for assessing preterm birth and stillbirth outcomes are other immediate research needs.

Conclusion

Preterm birth and stillbirth have multifactorial etiologies. More resources must be directed toward accelerating our understanding of these complex processes, and identifying upstream and cost-effective solutions that will improve these pregnancy outcomes.

Heterogeneity of preterm birth subtypes in relation to neonatal death

OBJECTIVE

To investigate the heterogeneity of preterm labor, preterm premature rupture of membranes (PROM), and indicated preterm birth in overall and gestational-age-specific neonatal death risk.

METHODS

We used 2001 U.S. linked birth/infant death (birth cohort) data sets for this analysis. We categorized three preterm birth subtypes according to reported preterm PROM, induction of labor, cesarean delivery, and pregnancy and labor complications. We used Cox proportional hazard models to calculate covariates adjusted hazard ratios (HRs) for neonatal death (0-27 days of life) among preterm neonates born at 24-27, 28-31, 32-33, and 34-36 weeks of gestation, with preterm labor being the referent.

RESULTS

There were 3,763,306 singleton live births at 24-44 weeks of gestation in the data set. Preterm PROM, indicated preterm birth, and preterm labor had neonatal death risk of 2.7%, 1.8%, and 1.1%, respectively. Compared with preterm labor, preterm PROM had shorter gestational age and lower birth weight, so did indicated preterm birth but to a lesser extent. Preterm PROM and indicated preterm birth after 28 weeks of gestation were associated with higher neonatal death risk than preterm labor. At 34-36 weeks of gestation, the HR of preterm PROM was 1.53 (95% confidence interval 1.20-1.95), and the HR of indicated preterm birth was 2.06 (95% confidence interval 1.83-2.33). The increased risk from preterm PROM and indicated preterm birth was not limited to early neonatal death in the first 7 days.

CONCLUSION

Preterm PROM and indicated preterm birth had higher risk of neonatal death than preterm labor, indicating heterogeneity in gestational age distribution and gestational-age-specific neonatal death risk.

LEVEL OF EVIDENCE

II.

The effect of changing patterns of obstetric care in Scotland (1980-2004) on rates of preterm birth and its neonatal consequences: perinatal database study

BACKGROUND

Rates of preterm birth are rising worldwide. Studies from the United States and Latin America suggest that much of this rise relates to increased rates of medically indicated preterm birth. In contrast, European and Australian data suggest that increases in spontaneous preterm labour also play a role. We aimed, in a population-based database of 5 million people, to determine the temporal trends and obstetric antecedents of singleton preterm birth and its associated neonatal mortality and morbidity for the period 1980-2004.

METHODS AND FINDINGS

There were 1.49 million births in Scotland over the study period, of which 5.8% were preterm. We found a percentage increase in crude rates of both spontaneous preterm birth per 1,000 singleton births (10.7%, p<0.01) and medically indicated preterm births (41.2%, p<0.01), which persisted when adjusted for maternal age at delivery. The greater proportion of spontaneous preterm births meant that the absolute increase in rates of preterm birth in each category were similar. Of specific maternal complications, essential and pregnancy-induced hypertension, pre-eclampsia, and placenta praevia played a decreasing role in preterm birth over the study period, with gestational and pre-existing diabetes playing an increasing role. There was a decline in stillbirth, neonatal, and extended perinatal mortality associated with preterm birth at all gestation over the study period but an increase in the rate of prolonged hospital stay for the neonate. Neonatal mortality improved in all subgroups, regardless of obstetric antecedent of preterm birth or gestational age. In the 28 wk and greater gestational groups we found a reduction in stillbirths and extended perinatal mortality for medically induced but not spontaneous preterm births (in the absence of maternal complications) although at the expense of a longer stay in neonatal intensive care. This improvement in stillbirth and neonatal mortality supports the decision making behind the 34% increase in elective/induced preterm birth in these women. Although improvements in neonatal outcomes overall are welcome, preterm birth still accounts for over 66% of singleton stillbirths, 65% of singleton neonatal deaths, and 67% of infants whose stay in the neonatal unit is "prolonged," suggesting this condition remains a significant contributor to perinatal mortality and morbidity.

CONCLUSIONS

In our population, increases in spontaneous and medically induced preterm births have made equal contributions to the rising rate of preterm birth. Despite improvements in related perinatal mortality, preterm birth remains a major obstetric and neonatal problem, and its frequency is increasing. Please see later in the article for the Editors' Summary.

A systematic review of intentional delivery in women with preterm prelabor rupture of membranes

OBJECTIVE

To evaluate the effect of intentional delivery versus expectant management in women with preterm prelabor rupture of membranes (PPROM).

METHODS

We searched electronic databases and trials registries, contacted experts, and checked reference lists of relevant studies. Studies were included if they were randomized controlled trials comparing intentional delivery versus expectant management after PPROM, the gestational age of participants was between 30 and 36 weeks, and the study reported one of several pre-determined outcomes.

RESULTS

Four studies were included in the meta-analysis. No difference was found between intentional delivery and expectant management in neonatal intensive care unit (NICU) length of stay (LOS) (weighted mean difference (WMD) -0.81 day, 95% confidence interval (CI) -1.66, 0.04), respiratory distress syndrome (risk difference (RD) -0.01, 95% CI -0.07, 0.06), and confirmed neonatal sepsis (RD -0.01, 95% CI -0.05, 0.04). One study found a significantly lower incidence of suspected neonatal sepsis among the intentional delivery group (RD -0.31, 95% CI -0.50, -0.12; number needed to treat (NNT) 3, 95% CI 2, 8). Maternal LOS was significantly shorter for the intentional delivery group (WMD -1.39 day, 95% CI -2.03, -0.75). There was a significant difference in the incidence of clinical chorioamnionitis favoring intentional delivery (RD -0.16, 95% CI -0.23, -0.10; NNT 6, 95% CI 5, 11). There was no significant difference in the incidence of other maternal outcomes, including cesarean section (RD 0.05, 95% CI -0.01, 0.11).

CONCLUSIONS

Intentional delivery may be favorable to expectant management for some maternal outcomes (chorioamnionitis and LOS). There is insufficient evidence to suggest that either strategy is beneficial or harmful for the baby. Large multicenter trials with primary neonatal outcomes are required to assess whether intentional delivery is associated with less neonatal morbidity.

Primiparity: An ‘intermediate’ risk group for spontaneous and medically indicated preterm birth

OBJECTIVE

Most women in their first pregnancy are at 'unknown' risk for preterm birth. We hypothesized that such women may be at an increased risk for preterm birth in comparison to those with a prior term birth.

METHODS

We used Missouri's maternally-linked data (1989-97), comprised of women delivering their first singleton live birth (N = 259 431) and women delivering their first two consecutive singleton live births (N = 154 810). We compared preterm birth (<37 weeks) rates among women with a previous term birth, women with no reproductive history (primiparous women), and in those with a previous preterm birth. Risks of spontaneous and medically indicated preterm birth were also examined after adjustments for confounders through multivariate log-binomial regression models.

RESULTS

Preterm birth rates were 8.1%, 9.6%, and 23.3% among women with a previous term birth, among primiparous women, and among those with a previous preterm birth, respectively. In comparison to women with a prior term birth, risks of spontaneous preterm birth among primiparous women and among women with a prior preterm birth were 1.1-fold (95% confidence interval (CI) 1.0, 1.2) and 2.5-fold (95% CI 2.4, 2.6) higher, respectively. These risks were higher for medically indicated preterm birth among both primiparous women (RR 1.3, 95% CI 1.2, 1.4) and those with a prior preterm birth (RR 3.2, 95% CI 3.0, 3.5) than for spontaneous preterm births.

CONCLUSIONS

Primiparous women are at increased risk of both medically indicated and spontaneous preterm birth. The findings suggest that studies on preterm birth should consider a risk assignment to include three groups: low-risk (prior term birth), intermediate risk (primiparity), and high-risk (prior preterm birth). This strategy will be informative for the identification of women with impending risk of delivering preterm, and complications associated with prematurity.

The risk for impaired learning-related abilities in childhood and educational attainment among adults born near-term

OBJECTIVE

To examine whether near-term births (NTB) and small-for-gestational-age (SGA) infants are at high risk for childhood learning-related problems and poor adult educational attainment, and whether poverty amplifies the adverse effects of NTB and SGA on those outcomes.

METHODS

A randomly selected birth cohort (n = 1,619) was followed into adulthood. IQ and learning abilities were measured in childhood and educational attainment was measured in adulthood.

RESULTS

NTB (n = 226) and SGA (n = 154) were associated with lower educational attainment mediated through learning-related abilities at age 7. Childhood poverty moderated the impact of NTB on educational attainment both directly and mediated through lower learning-related abilities. Poverty did not moderate the effect of SGA.

CONCLUSIONS

Poorer learning-related outcomes and educational attainment were not limited to children born very (<32 weeks) or extremely (<28 weeks) preterm, especially among those living in poverty. Targeted interventions such as remedial learning during childhood among NTB in poor families may yield higher educational attainment.

Early rapid growth, early birth: accelerated fetal growth and spontaneous late preterm birth

The past two decades in the United States have seen a 24% rise in spontaneous late preterm delivery (34-36 weeks) of unknown etiology. This study tested the hypothesis that fetal growth was identical prior to spontaneous preterm (n = 221, median gestational age at birth 35.6 weeks) and term (n = 3706) birth among pregnancies followed longitudinally in Santiago, Chile. The hypothesis was not supported: Preterm-delivered fetuses were significantly larger than their term-delivered peers by mid-second trimester in estimated fetal weight, head, limb, and abdominal dimensions, and they followed different growth trajectories. Piecewise regression assessed time-specific differences in growth rates at 4-week intervals from 16 weeks. Estimated fetal weight and abdominal circumference growth rates slowed at 20 weeks among the preterm-delivered, only to match and/or exceed their term-delivered peers at 24-28 weeks. After an abrupt growth rate decline at 28 weeks, fetuses delivered preterm did so at greater population-specific sex and age-adjusted birth weight percentiles than their peers from uncomplicated pregnancies (P < 0.01). Growth rates predicted birth timing: one standard score of estimated fetal weight increased the odds ratio for late preterm birth from 2.8 prior to 23 weeks, to 3.6 (95% confidence interval, 1.82-7.11, P < 0.05) between 23 and 27 weeks. After 27 weeks, increasing size was protective (OR: 0.56, 95% confidence interval, 0.38-0.82, P = 0.003). These data document, for the first time, a distinctive fetal growth pattern across gestation preceding spontaneous late preterm birth, identify the importance of mid-gestation for alterations in fetal growth, and add perspective on human fetal biological variability.

Development of the forward parachute reaction and the age of walking in near term infants: a longitudinal observational study

BACKGROUND

Near term infants are a main part of preterms. They are at higher risk for mortality and morbidity than term infants and could show a quite different development of tone and reflexes from them. The aim of the present study was to describe longitudinally, in a large sample of healthy near term infants, the development of the forward parachute reaction (FPR) and its correlation with the age of acquisition of independent walking.

METHODS

The assessment of FPR (as absent, incomplete or complete) was performed at 3, 6, 9, 12 months of corrected age in 484 infants, with a gestational age between 35.0 and 36.9 weeks. The age of acquisition of independent walking was monitored until its appearance. A correlation analysis was done between the age of walking and the acquisition of a complete or incomplete FPR, using the Spearman Rank correlation. The Mann-Withney U test was used to identify significant gestational age differences for the age of FPR appearance.

RESULTS

Most of infants had a two-step development pattern. In fact, they showed at first an incomplete and then a complete FPR, which was observed more frequently at 9 months. An incomplete FPR only, without a successive maturation to a complete FPR, was present in the 21% of the whole sample. Infants with a complete FPR walked at a median age of 13 months, whereas those with an incomplete FPR only walked at a median age of 14 months.

CONCLUSION

We identified two groups within our sample of near term infants. The first group showed a progressive maturation of FPR, whereas the second one was characterised by the inability to get a complete pattern, within the one year observation's period. Furthermore, we observed a trend toward a delayed acquisition of independent walking in the latter group of infants.

Pregnancy disorders that lead to delivery before the 28th week of gestation: an epidemiologic approach to classification

Epidemiologists have grouped the multiple disorders that lead to preterm delivery before the 28th week of gestation in a variety of ways. The authors sought to identify characteristics that would help guide how to classify disorders that lead to such preterm delivery. They enrolled 1,006 women who delivered a liveborn singleton infant of less than 28 weeks' gestation at 14 centers in the United States between 2002 and 2004. Each delivery was classified by presentation: preterm labor (40%), prelabor premature rupture of membranes (23%), preeclampsia (18%), placental abruption (11%), cervical incompetence (5%), and fetal indication/intrauterine growth restriction (3%). Using factor analysis (eigenvalue = 1.73) to compare characteristics identified by standardized interview, chart review, placental histology, and placental microbiology among the presentation groups, the authors found 2 broad patterns. One pattern, characterized by histologic chorioamnionitis and placental microbe recovery, was associated with preterm labor, prelabor premature rupture of membranes, placental abruption, and cervical insufficiency. The other, characterized by a paucity of organisms and inflammation but the presence of histologic features of dysfunctional placentation, was associated with preeclampsia and fetal indication/intrauterine growth restriction. Disorders leading to preterm delivery may be separated into two groups: those associated with intrauterine inflammation and those associated with aberrations of placentation.

Medically indicated preterm birth: recognizing the importance of the problem

Preterm birth complicates over 500,000 births annually, affecting 12.5% of pregnancies in the United States. Much of the temporal increase in preterm birth (<37 weeks) over the past decade is largely driven by a concurrent temporal increase in medically indicated preterm birth. Maternal and fetal indications that prompt an intervention at preterm gestational ages include preeclampsia, intrauterine growth restriction, and placental abruption-conditions that constitute "ischemic placental disease." Ischemic placental disease is implicated in over one of every two indicated preterm births compared with less than one in five births at term. Comprehensive evaluation of risk factors, with careful consideration of heterogeneity in the syndrome of medically indicated preterm birth and ischemic placental disease may provide important clues to predict and consequently prevent preterm birth.

Parents' mental health after the birth of an extremely preterm child: a comparison between bereaved and non-bereaved parents

OBJECTIVE

To assess the impact of extremely preterm birth (24-26 weeks of gestation) on the mental health of parents two to six years after delivery, and to examine potential differences in post-traumatic growth between parents whose newborn infant died and those whose child survived.

METHOD

A total of 54 parents who had lost their newborn and 38 parents whose preterm child survived were assessed by questionnaires with regard to depression and anxiety (HADS) and post-traumatic growth (PTGI).

RESULTS

Neither group of parents had clinically relevant levels of depression and anxiety. Mothers showed higher levels of anxiety than fathers. Bereaved parents with no other, living child reported higher levels of depression than bereaved parents with one or more children. Mothers reported higher post-traumatic growth compared to fathers. In particular, bereaved mothers experienced the value and quality of their close social relationships more positively compared to the non-bereaved parents.

CONCLUSION

In the long term, bereaved and non-bereaved parents cope reasonably well with an extremely preterm birth of a child. Post-traumatic growth appears to be positively related to bereavement, particularly in mothers.