The rate of preterm birth in the United States is affected by the method of gestational age assignment

Predicting preterm births from electrohysterogram recordings via deep learning

About one in ten babies is born preterm, i.e., before completing 37 weeks of gestation, which can result in permanent neurologic deficit and is a leading cause of child mortality. Although imminent preterm labor can be detected, predicting preterm births more than one week in advance remains elusive. Here, we develop a deep learning method to predict preterm births directly from electrohysterogram (EHG) measurements of pregnant mothers recorded at around 31 weeks of gestation. We developed a prediction model, which includes a recurrent neural network, to predict preterm births using short-time Fourier transforms of EHG recordings and clinical information from two public datasets. We predicted preterm births with an area under the receiver-operating characteristic curve (AUC) of 0.78 (95% confidence interval: 0.76-0.80). Moreover, we found that the spectral patterns of the measurements were more predictive than the temporal patterns, suggesting that preterm births can be predicted from short EHG recordings in an automated process. We show that preterm births can be predicted for pregnant mothers around their 31st week of gestation, prompting beneficial treatments to reduce the incidence of preterm births and improve their outcomes.

Association of Gestational Age with Postpartum Hemorrhage: An International Cohort Study

BACKGROUND

Risk factors for postpartum hemorrhage, such as chorioamnionitis and multiple gestation, have been identified in previous epidemiologic studies. However, existing data describing the association between gestational age at delivery and postpartum hemorrhage are conflicting. The aim of this study was to assess the association between gestational age at delivery and postpartum hemorrhage.

METHODS

The authors conducted a population-based retrospective cohort study of women who underwent live birth delivery in Sweden between 2014 and 2017 and in California between 2011 and 2015. The primary exposure was gestational age at delivery. The primary outcome was postpartum hemorrhage, classified using International Classification of Diseases, Ninth Revision-Clinical Modification codes for California births and a blood loss greater than 1,000 ml for Swedish births. The authors accounted for demographic and obstetric factors as potential confounders in the analyses.

RESULTS

The incidences of postpartum hemorrhage in Sweden (23,323/328,729; 7.1%) and in California (66,583/2,079,637; 3.2%) were not comparable. In Sweden and California, the incidence of postpartum hemorrhage was highest for deliveries between 41 and 42 weeks' gestation (7,186/75,539 [9.5%] and 8,921/160,267 [5.6%], respectively). Compared to deliveries between 37 and 38 weeks, deliveries between 41 and 42 weeks had the highest adjusted odds of postpartum hemorrhage (1.62 [95% CI, 1.56 to 1.69] in Sweden and 2.04 [95% CI, 1.98 to 2.09] in California). In both cohorts, the authors observed a nonlinear (J-shaped) association between gestational age and postpartum hemorrhage risk, with 39 weeks as the nadir. In the sensitivity analyses, similar findings were observed among cesarean deliveries only, when postpartum hemorrhage was classified only by International Classification of Diseases, Tenth Revision-Clinical Modification codes, and after excluding women with abnormal placentation disorders.

CONCLUSIONS

The postpartum hemorrhage incidence in Sweden and California was not comparable. When assessing a woman's risk for postpartum hemorrhage, clinicians should be aware of the heightened odds in women who deliver between 41 and 42 weeks' gestation.

EDITOR’S PERSPECTIVE

Smoking during Pregnancy and Adverse Birth and Maternal Outcomes in California, 2007 to 2016

OBJECTIVE

This study aimed to determine associations between maternal cigarette smoking and adverse birth and maternal outcomes.

STUDY DESIGN

This is a 10-year population-based retrospective cohort study including 4,971,896 resident births in California. Pregnancy outcomes of maternal smokers were compared with those of nonsmokers. The outcomes of women who stopped smoking before or during various stages of pregnancy were also investigated.

RESULTS

Infants of women who smoked during pregnancy were twice as likely to have low birth weight (LBW) and be small for gestational age (SGA), 57% more likely to have very LBW (VLBW) or be a preterm birth (PTB), and 59% more likely to have a very PTB compared with infants of nonsmokers. During the study period, a significant widening of gaps developed in both rates of LBW and PTB and the percentage of SGA between infants of maternal smokers and nonsmokers.

CONCLUSION

Smoking during pregnancy is associated with a significantly increased risk of adverse birth and maternal outcomes, and differences in rates of LBW, PTB, and SGA between infants of maternal smokers and nonsmokers increased during this period. Stopping smoking before pregnancy or even during the first trimester significantly decreased the infant risks of LBW, PTB, SGA, and the maternal risk for cesarean delivery.

Maternal and infant predictors of infant mortality in California, 2007-2015

Objective

To identify current maternal and infant predictors of infant mortality, including maternal sociodemographic and economic status, maternal perinatal smoking and obesity, mode of delivery, and infant birthweight and gestational age.

Methods

This retrospective study analyzed data from the linked birth and infant death files (birth cohort) and live births from the Birth Statistical Master files (BSMF) in California compiled by the California Department of Public Health for 2007–2015. The birth cohort study comprised 4,503,197 singleton births including 19,301 infant deaths during the nine-year study period. A subpopulation to study fetal growth consisted of 4,448,300 birth cohort records including 13,891 infant deaths.

Results

The infant mortality rate (IMR) for singleton births decreased linearly (p <0.001) from 4.68 in 2007 to 3.90 (per 1,000 live births) in 2015. However, significant disparities in IMR were uncovered in different population groups depending upon maternal sociodemographic and economic characteristics and maternal characteristics during pregnancy. Children of African American women had almost twice the risk of infant mortality when compared with children of White women (AOR 2.12; 95% CI, 1.98–2.27; p<0.001). Infants of women with Bachelor’s degrees or higher were 89% less likely to die (AOR 1.89; 95% CI, 1.76–2.04; p<0.001) when compared to infants of women with education less than high school. Infants of maternal smokers were 75% more likely to die (AOR 1.75; 95% CI, 1.58–1.93; p<0.001) than infants of nonsmokers. Infants of women who were overweight and obese during pregnancy accounted for 55% of IMR over all women in the study. More than half of the infant deaths were to children of women with lower socioeconomic status; infants of WIC participants were 59% more likely to die (AOR 1.59; 95% CI, 1.52–1.67; p<0.001) than infants of non-WIC participants. With respect to infant predictors, infants born with LBW or PTB were more than six times (AOR 6.29; 95% CI, 5.90–6.70; p<0.001) and almost four times (AOR 3.95; 95% CI, 3.73–4.19; p<0.001) more likely to die than infants who had normal births, respectively. SGA and LGA infants were more than two times (AOR 2.03; 95% CI, 1.92–2.15; p<0.001) and 41% (AOR 1.41; 95% CI, 1.32–1.52; p<0.001) more likely to die than AGA infants, respectively.

Conclusions

While the overall IMR in California is declining, wide disparities in death rates persist in different groups, and these disparities are increasing. Our data indicate that maternal sociodemographic and economic factors, as well as maternal prepregnancy obesity and smoking during pregnancy, have a prominent effect on IMR though no causality can be inferred with the current data. These predictors are not typically addressed by direct medical care. Infant factors with a major effect on IMR are birthweight and gestational age—predictors that are addressed by active medical services. The highest value interventions to reduce IMR may be social and public health initiatives that mitigate disparities in sociodemographic, economic and behavioral risks for mothers.

Anesthesia management in 14 cases of cesarean delivery in renal transplant patients-a single-center retrospective observational study

Background

The aim of this study was to investigate anesthesia management for cesarean delivery in renal transplant patients.

Methods

The details of anesthesia management, patient characteristics, surgical information, and renal and maternal outcomes were retrospectively investigated in 14 post-renal transplant patients who underwent cesarean delivery at a single university hospital between January 1, 2014, and August 31, 2018.

Results

Five patients were managed under general anesthesia, and nine cases were under regional anesthesia. Nine cases were emergency surgeries. The mean (SD) age was 35.5 (4.4) years, pregnancy body weight was 56.8 (10.0) kg, and gestational age was 33.3 (4.1) weeks. Nine cases were preterm deliveries. Five cases showed hypertension prior to pregnancy, and 13 patients showed hypertension before cesarean delivery. The preoperative creatinine level was 1.49 (0.53) mg/dL. The intraoperative maximum systolic/diastolic blood pressure was 170 (20)/102 (15) mmHg, and the intraoperative minimum systolic/diastolic blood pressure was 97 (13)/49 (12) mmHg. A total of six patients had either mean arterial pressure < 65 mmHg or required vasopressors. Serum creatinine remained unchanged after surgery compared with the preoperative level.

Conclusion

Cesarean delivery was often performed in post-renal transplant patients for preterm delivery or as emergency surgery, with a higher ratio of regional anesthesia to general anesthesia. Since both hypertension and hypotension are most likely to occur during cesarean delivery, circulation management can be difficult, and anesthesia should be managed so as to maintain sufficient renal perfusion and ensure postoperative renal function.

The predictive capacity of uterine artery Doppler for preterm birth-A cohort study

Introduction

Mid‐trimester uterine artery resistance measured with Doppler sonography is predictive for iatrogenic preterm birth. In view of the emerging association between hypertensive disease in pregnancy and spontaneous preterm birth, we hypothesized that uterine artery resistance could also predict spontaneous preterm birth.

Material and methods

We performed a cohort study of women with singleton pregnancies. Uterine artery resistance was routinely measured at the 18‐22 weeks anomaly scan. Pregnancies complicated by congenital anomalies or intrauterine fetal death were excluded. We analyzed if the waveform of the uterine artery (no notch, unilateral notch or bilateral notch) was predictive for spontaneous and iatrogenic preterm birth, defined as delivery before 37 weeks of gestation. Furthermore, we assessed whether the uterine artery pulsatility index was associated with the risk of preterm birth.

Results

Between January 2009 and December 2016 we collected uterine Doppler indices and relevant outcome data in 4521 women. Mean gestational age at measurement was 19⁺⁶ weeks. There were 137 (3.0%) women with a bilateral and 213 (4.7%) with a unilateral notch. Mean gestational age at birth was 38⁺⁶ weeks. Spontaneous and iatrogenic preterm birth rates were 5.7% and 4.9%, respectively. Mean uterine artery resistance was 1.12 in the spontaneous preterm birth group compared with 1.04 in the term group (P = 0.004) The risk of preterm birth was increased with high uterine artery resistance (OR 2.9 per unit; 95% CI 2.4‐3.9). Prevalence of spontaneous preterm birth increased from 5.5% in women without a notch in the uterine arteries to 8.0% in women with a unilateral notch and 8.0% in women with a bilateral notch. For iatrogenic preterm birth, these rates were 3.9%, 13.6% and 23.4%, respectively. Likelihood ratios for the prediction of spontaneous preterm birth were 1.6 (95% CI 1.0‐2.6) and 1.9 (95% CI 1.0‐3.5) for unilateral and bilateral notches, respectively, and for iatrogenic preterm birth they were 3.6 (95% CI 2.5‐5.2) and 6.8 (95% CI 4.7‐9.9) for unilateral and bilateral notches, respectively. Of all women with bilateral notching, 31.4% delivered preterm.

Conclusions

Mid‐trimester uterine artery resistance measured at 18‐22 weeks of gestation is a weak predictor of spontaneous preterm birth.

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

BACKGROUND

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

OBJECTIVE

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

CONCLUSIONS

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

PROSPERO

CDR42017082190.

Impact of cervical length on preterm birth in northern China: a prospective cohort study

Aim: To evaluate the association between cervical length (CL) and certain subtypes of preterm birth (PTB).Materials and methods: Data were derived from a prospective cohort study conducted in China to explore the risk factors of PTB between 2012 and 2014. Gestational age was based on transvaginal ultrasound examination during pregnancy. PTB was categorized into two subtypes according to its clinical symptoms. Logistic regression was used to evaluate the relation between short CL and certain subtypes of PTB, adjusted for potential confounders.Results: Of the 3688 women included in the analysis, 425 (11.5%) women had a CL less than 30 mm (short CL). The incidence of PTB was significantly higher in the short CL group than the normal CL group (10.6 versus 6.0%; adjusted risk ratio (RR) 1.91, 95% CI 1.35, 2.69). The association between short CL and overall PTB was both significant in primipara (adjusted RR 2.00, 95% CI 1.09, 3.68) and multipara (adjusted RR 1.89, 95% CI 1.24, 2.87). The association between short CL and noniatrogenic PTB related to parity (primipara adjusted RR 2.13, 95% CI 1.11, 4.10; multipara adjusted RR 1.90, 95% CI 1.21, 3.00).Conclusion: Short CL could increase the risk of overall PTB and noniatrogenic PTB. The association between CL and noniatrogenic PTB was dependent on parity.

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

Background

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

Methods

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

Results

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

Conclusions

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

Electronic supplementary material

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

[A single-center study on the incidence and mortality of preterm infants from 2006 to 2016]

OBJECTIVE

To investigate the incidence and mortality rates of preterm infants and the main causes of death.

METHODS

The basic information of preterm infants was collected from their medical records and admission/discharge records to analyze the incidence and mortality rates of preterm infants and the causes of their death.

RESULTS

There were 76 812 neonates born in the Xuzhou Maternal and Child Health Hospital from January 2006 to December 2016, among whom 5 585 (7.27%) were preterm infants. The incidence rate of preterm infants tended to increase over these years (P&lt;0.001). The overall mortality rate was 5.01% (280/5 585), and the mortality rate tended to decrease over these years (P&lt;0.001). The mortality rate increased with the reductions in birth weight and gestational age (P&lt;0.001). The top four causes of death in preterm infants were respiratory distress syndrome (44.3%), severe asphyxia (12.9%), neonatal malformation (4.3%), and pulmonary hemorrhage (2.9%) respectively. With the increase in birth weight, there were significant reductions in the constituent ratios of death due to respiratory distress syndrome and severe asphyxia (P&lt;0.001).

CONCLUSIONS

The incidence rate of preterm infants tended to increase and their mortality rate tended to decrease from 2006 to 2016. The mortality rate of preterm infants is associated with gestational age and birth weight. Respiratory distress syndrome and severe asphyxia are the main causes of death in preterm infants.

Investigating the Prevalence of Preterm Birth in Iranian Population: A Systematic Review and Meta-Analysis

Introduction: Despite medical advances, preterm delivery remains a global problem in developed and developing countries. The present study was aimed at conducting a systematic review and meta-analysis of studies on the prevalence of preterm delivery in Iran.

Methods: This study was carried out on studies conducted in Iran by searching databases of SID, Magiran, Irandoc, MEDLIB, Iranmedex, PubMed, Web of science, Google Scholar and Scopus. The search was conducted using advanced search and keywords of preterm delivery and equivalents of it in Mesh and their Farsi’s Synonymous in all articles from 2000-2016.After extracting the data, the data were combined using a random model. Heterogeneity of the studies was assessed using Q test I2 index and the data were analyzed using STATA Ver.11 software.

Results: The total number of samples in this study was 41773. In 19 reviewed articles, the overall prevalence of preterm delivery, based on the random effects model, was estimated to be a total of 10% (95% CI, 9-12). The lowest prevalence of preterm labor was 5.4% in Bam and the highest prevalence was 19.85% in Tehran. There was no significant difference between the prevalence of preterm delivery compared to year of study and sample size.

Conclusion: This study reviewed the findings of previous studies and showed that preterm delivery is a relatively prevalent problem in Iran. Therefore, adopting appropriate interventions in many cases including life skills training, self-care and increasing pregnancy care to reduce these consequences and their following complications in high risk patients seem necessary.

Should delivery timing for repeat cesarean be reconsidered based on dating criteria?

PURPOSE

We sought to examine if the method of pregnancy dating at five increasing term gestational ages is associated with increasing neonatal morbidity.

MATERIALS AND METHODS

A cohort of women who underwent elective repeat cesarean delivery at ≥37 weeks' gestation were identified from the NICHD MFMU Network registry. We excluded women who were in labor, those carrying a fetus with a congenital anomaly, those with a non-reassuring fetal heart tracing, and those with preeclampsia, preexisting chronic hypertension or diabetes. Composite neonatal morbidity was defined for our study as any of the following: NICU admission, hypotonia, meconium aspiration, seizures, need for ventilator support, NEC, RDS, TTN, hypoglycemia, or neonatal death. We compared composite neonatal morbidity rates among infants born at five different gestational age cutoffs according to their method of pregnancy dating.

RESULTS

At 39 and 40 weeks' gestation, the lowest rate of neonatal complications was seen in pregnancies dated by first trimester ultrasound (5.8% and 5.5%, respectively), while those with the highest neonatal morbidity rates were seen when dated by a second or third trimester ultrasound (8.1% and 6.0%, respectively); p < .001. Additionally within each pregnancy dating category, the neonatal morbidity rates declined from 37 to 40 weeks' gestation and then significantly increased at 41 + 0 weeks' gestation.

CONCLUSION

Even with suboptimal dating methods, amongst women undergoing elective repeat cesarean delivery, neonatal morbidity was lowest when delivery occurred between 40 and 40 + 6 weeks gestation.

Research standardization tools: pregnancy measures in the PhenX Toolkit

Only through concerted and well-executed research endeavors can we gain the requisite knowledge to advance pregnancy care and have a positive impact on maternal and newborn health. Yet the heterogeneity inherent in individual studies limits our ability to compare and synthesize study results, thus impeding the capacity to draw meaningful conclusions that can be trusted to inform clinical care. The PhenX Toolkit (http://www.phenxtoolkit.org), supported since 2007 by the National Institutes of Health, is a web-based catalog of standardized protocols for measuring phenotypes and exposures relevant for clinical research. In 2016, a working group of pregnancy experts recommended 15 measures for the PhenX Toolkit that are highly relevant to pregnancy research. The working group followed the established PhenX consensus process to recommend protocols that are broadly validated, well established, nonproprietary, and have a relatively low burden for investigators and participants. The working group considered input from the pregnancy experts and the broader research community and included measures addressing the mode of conception, gestational age, fetal growth assessment, prenatal care, the mode of delivery, gestational diabetes, behavioral and mental health, and environmental exposure biomarkers. These pregnancy measures complement the existing measures for other established domains in the PhenX Toolkit, including reproductive health, anthropometrics, demographic characteristics, and alcohol, tobacco, and other substances. The preceding domains influence a woman's health during pregnancy. For each measure, the PhenX Toolkit includes data dictionaries and data collection worksheets that facilitate incorporation of the protocol into new or existing studies. The measures within the pregnancy domain offer a valuable resource to investigators and clinicians and are well poised to facilitate collaborative pregnancy research with the goal to improve patient care. To achieve this aim, investigators whose work includes the perinatal population are encouraged to utilize the PhenX Toolkit in the design and implementation of their studies, thus potentially reducing heterogeneity in data measures across studies. Such an effort will enhance the overall impact of individual studies, increasing the ability to draw more meaningful conclusions that can then be translated into clinical practice.

The effect of maternal age on fetal and neonatal mortality

OBJECTIVE

Determine the gestational age at which the risk of fetal or neonatal death associated with delaying delivery by 1 week exceeds the risk of neonatal death associated with immediate delivery, stratified by maternal age intervals.

STUDY DESIGN

We conducted a retrospective cohort study of live births, stillbirths and neonatal deaths that occurred in the United States between 2010 and 2013 using birth data. Women were classified into six age categories. Singleton, non-anomalous pregnancies without hypertensive disease or diabetes were included. Relative risks were obtained using a generalized linear model comparing the rate of death associated with immediate delivery to those of expectant management.

RESULTS

For all age groups with the exception of women 44 years and older, immediate delivery was associated with lower relative risk of death by 39 weeks. For <25, 25 to 29, 30 to 34, 35 to 39, 40 to 44, odds ratios (OR) and confidence intervals (CI) were 1.0 (0.32 to 3.10), 0.67 (0.19 to 2.37), 0.80 (0.21 to 2.98), 0.67 (0.19 to 2.36) and 0.45 (0.16 to 1.31), respectively. In women 44 years and older, immediate delivery was associated with a lower relative risk of death by 38 weeks (OR: 0.35, CI: 0.14 to 0.90).

CONCLUSION

Women greater than 44 years old may benefit from delivery by 38 weeks gestational age to reduce the risk of stillbirth.

Adverse Infant Outcomes Associated with Discordant Gestational Age Estimates

BACKGROUND

Gestational age estimation by last menstrual period (LMP) vs. ultrasound (or best obstetric estimate in the US) may result in discrepant classification of preterm vs. term birth. We investigated whether such discrepancies are associated with adverse infant outcomes.

METHODS

We studied singleton livebirths in the Medical Birth Registries of Norway, Sweden and Finland and US live birth certificates from 1999 to the most recent year available. Risk ratios (RR) with 95% confidence intervals (CI) by discordant and concordant gestational age estimation for infant, neonatal and post-neonatal mortality, Apgar score <4 and <7 at 5 min, and neonatal intensive care unit (NICU) admission were estimated using generalised linear models, adjusting for maternal age, education, parity, year of birth, and infant sex. Results were presented stratified by country.

RESULTS

Compared to infants born at term by both methods, infants born preterm by ultrasound/best obstetric estimate but term by LMP had higher infant mortality risks (range of adjusted RRs 3.9 to 7.2) and modestly higher risks were obtained among infants born preterm by LMP but term by ultrasound/best obstetric estimate (range of adjusted RRs 1.6 to 1.9). Risk estimates for the other outcomes showed the same pattern. These findings were consistent across all four countries.

CONCLUSIONS

Infants classified as preterm by ultrasound/best estimate, but term by LMP have consistently higher risks of adverse outcomes than those classified as preterm by LMP but term by ultrasound/best estimate. Compared with ultrasound/best estimate, use of LMP overestimates the proportion of births that are preterm.

Variations in very preterm birth rates in 30 high-income countries: are valid international comparisons possible using routine data?

OBJECTIVE

Concerns about differences in registration practices across countries have limited the use of routine data for international very preterm birth (VPT) rate comparisons.

DESIGN

Population-based study.

SETTING

Twenty-seven European countries, the United States, Canada and Japan in 2010.

POPULATION

A total of 9 376 252 singleton births.

METHOD

We requested aggregated gestational age data on live births, stillbirths and terminations of pregnancy (TOP) before 32 weeks of gestation, and information on registration practices for these births. We compared VPT rates and assessed the impact of births at 22-23 weeks of gestation, and different criteria for inclusion of stillbirths and TOP on country rates and rankings.

MAIN OUTCOME MEASURES

Singleton very preterm birth rate, defined as singleton stillbirths and live births before 32 completed weeks of gestation per 1000 total births, excluding TOP if identifiable in the data source.

RESULTS

Rates varied from 5.7 to 15.7 per 1000 total births and 4.0 to 11.9 per 1000 live births. Country registration practices were related to percentage of births at 22-23 weeks of gestation (between 1% and 23% of very preterm births) and stillbirths (between 6% and 40% of very preterm births). After excluding births at 22-23 weeks, rate variations remained high and with a few exceptions, country rankings were unchanged.

CONCLUSIONS

International comparisons of very preterm birth rates using routine data should exclude births at 22-23 weeks of gestation and terminations of pregnancy. The persistent large rate variations after these exclusions warrant continued surveillance of VPT rates at 24 weeks and over in high-income countries.

TWEETABLE ABSTRACT

International comparisons of VPT rates should exclude births at 22-23 weeks of gestation and terminations of pregnancy.

Influence of Birthweight on the Prospective Stillbirth Risk in the Third Trimester: A Cross-Sectional Cohort Study

OBJECTIVE

The objective of this study was to determine the effect of birthweight on prospective stillbirth risk.

METHODS

Cross-sectional study of singleton births in the United States from 2010 to 2012 from 32 through 42 weeks was conducted. Stillbirth risk was stratified by birthweight and gestational age adjusted for time from death to delivery. The primary outcome was the prospective stillbirth risk for each birthweight category. Student t-test was used for continuous data, chi-square to compare categorical data. Binomial proportions were used to derive prospective and cumulative risks. Cox proportional hazards regression with log-rank test comparison for heterogeneity was used to compare birthweight categories and derive hazard ratios.

RESULTS

There was an increase in the risk for stillbirth as birthweight diverged from the reference group. At 40 weeks adjusted gestational age, stillbirth rate per 10,000 births for the bottom (6.17, 95% CI: 7.47-4.87) and top (2.37, 95%CI: 3.1-1.65) 5th centiles of birthweight conveyed the highest risk. Hazard ratios (HR) after adjusting for covariates were: 1.55 (1.73-1.4) <5th centile and 2.2 (2.43-1.99) > 95th centile (p < 0.001).

CONCLUSION

Stillbirth risk increases as birthweight departs from the mean. Birthweight below the 5th and above the 95th centile conveyed a significantly increased risk for stillbirth which was most noticeable after 37 weeks.

Cervical Length and Androgens in Pregnant Women With Polycystic Ovary Syndrome: Has Metformin Any Effect?

CONTEXT

Women with polycystic ovary syndrome (PCOS) have increased risk of preterm delivery. Shortening of the cervix is a sign of preterm delivery.

OBJECTIVE

This study aimed to investigate potential effect of metformin on cervical length and whether androgen levels correlate with cervical length in PCOS pregnancies.

DESIGN AND SETTING

This was a sub-study of a randomized, placebo-controlled, multicenter study (The PregMet study) performed at 11 secondary or tertiary centers from 2005 to 2009.

PARTICIPANTS

Two-hundred sixty-one pregnancies of 245 women with PCOS, age 18-42 years participated.

INTERVENTIONS

Participants were randomly assigned to metformin or placebo from first trimester to delivery.

OUTCOME MEASUREMENTS

We compared cervical length and androgen levels in metformin and placebo groups at gestational weeks 19 and 32. We also explored whether cervical length correlated with androgen levels.

RESULTS

We found no difference in cervical length between the metformin and the placebo groups at gestational week 19 and 32. Dehydroepiandrosterone (DHEAS) tended to be higher in the metformin group. There were no correlations between androgens and cervical length at week 19. At gestational week 32, androstenedione (P = .02) and DHEAS (P = .03) showed a trend toward negative correlation to cervical length. High androstenedione level correlated with shortening of cervical length from week 19 to 32 when adjusted for confounders (P = .003). T (P = .03), DHEAS (P = .02), and free testosterone index (P = .03) showed a similar trend.

CONCLUSION

Metformin in pregnancy did not affect cervical length in women with PCOS. High maternal androgen levels correlated with cervical shortening from the second to the third trimester of pregnancy, as a sign of cervical ripening.

Gestational dating by metabolic profile at birth: a California cohort study

BACKGROUND

Accurate gestational dating is a critical component of obstetric and newborn care. In the absence of early ultrasound, many clinicians rely on less accurate measures, such as last menstrual period or symphysis-fundal height during pregnancy, or Dubowitz scoring or the Ballard (or New Ballard) method at birth. These measures often underestimate or overestimate gestational age and can lead to misclassification of babies as born preterm, which has both short- and long-term clinical care and public health implications.

OBJECTIVE

We sought to evaluate whether metabolic markers in newborns measured as part of routine screening for treatable inborn errors of metabolism can be used to develop a population-level metabolic gestational dating algorithm that is robust despite intrauterine growth restriction and can be used when fetal ultrasound dating is not available. We focused specifically on the ability of these markers to differentiate preterm births (PTBs) (<37 weeks) from term births and to assign a specific gestational age in the PTB group.

STUDY DESIGN

We evaluated a cohort of 729,503 singleton newborns with a California birth in 2005 through 2011 who had routine newborn metabolic screening and fetal ultrasound dating at 11-20 weeks' gestation. Using training and testing subsets (divided in a ratio of 3:1) we evaluated the association among PTB, target newborn characteristics, acylcarnitines, amino acids, thyroid-stimulating hormone, 17-hydroxyprogesterone, and galactose-1-phosphate-uridyl-transferase. We used multivariate backward stepwise regression to test for associations and linear discriminate analyses to create a linear function for PTB and to assign a specific week of gestation. We used sensitivity, specificity, and positive predictive value to evaluate the performance of linear functions.

RESULTS

Along with birthweight and infant age at test, we included 35 of the 51 metabolic markers measured in the final multivariate model comparing PTBs and term births. Using a linear discriminate analyses-derived linear function, we were able to sort PTBs and term births accurately with sensitivities and specificities of ≥95% in both the training and testing subsets. Assignment of a specific week of gestation in those identified as PTBs resulted in the correct assignment of week ±2 weeks in 89.8% of all newborns in the training and 91.7% of those in the testing subset. When PTB rates were modeled using the metabolic dating algorithm compared to fetal ultrasound, PTB rates were 7.15% vs 6.11% in the training subset and 7.31% vs 6.25% in the testing subset.

CONCLUSION

When considered in combination with birthweight and hours of age at test, metabolic profile evaluated within 8 days of birth appears to be a useful measure of PTB and, among those born preterm, of specific week of gestation ±2 weeks. Dating by metabolic profile may be useful in instances where there is no fetal ultrasound due to lack of availability or late entry into care.

Porphyromonas gingivalis within Placental Villous Mesenchyme and Umbilical Cord Stroma Is Associated with Adverse Pregnancy Outcome

Intrauterine presence of Porphyromonas gingivalis (Pg), a common oral pathobiont, is implicated in preterm birth. Our aim was to determine if the location of Pg within placental and/or umbilical cord sections was associated with a specific delivery diagnosis at preterm delivery (histologic chorioamnionitis, chorioamnionitis with funisitis, preeclampsia, and preeclampsia with HELLP-syndrome, small for gestational age). The prevalence and location of Pg within archived placental and umbilical cord specimens from preterm (25 to 32 weeks gestation) and term control cohorts were evaluated by immunofluorescent histology. Detection of Pg was performed blinded to pregnancy characteristics. Multivariate analyses were performed to evaluate independent effects of gestational age, being small for gestational age, specific preterm delivery diagnosis, antenatal steroids, and delivery mode, on the odds of having Pg in the preterm tissue. Within the preterm cohort, 49 of 97 (51%) placentas and 40 of 97 (41%) umbilical cord specimens were positive for Pg. Pg within the placenta was significantly associated with shorter gestation lengths (OR 0.63 (95%CI: 0.48–0.85; p = 0.002) per week) and delivery via caesarean section (OR 4.02 (95%CI: 1.15–14.04; p = 0.03), but not with histological chorioamnionitis or preeclampsia. However, the presence of Pg in the umbilical cord was significantly associated with preeclampsia: OR 6.73 (95%CI: 1.31–36.67; p = 0.02). In the term cohort, 2 of 35 (6%) placentas and no umbilical cord term specimens were positive for Pg. The location of Pg within the placenta was different between preterm and term groups in that Pg within the villous mesenchyme was only detected in the preterm cohort, whereas Pg associated with syncytiotrophoblasts was found in both preterm and term placentas. Taken together, our results suggest that the presence of Pg within the villous stroma or umbilical cord may be an important determinant in Pg-associated adverse pregnancy outcomes.