[Epidemiology and risk factors for preterm births in north-western Algeria]

Introduction

preterm births continue to be the main cause of infant and child mortality as well as sensory-motor disabilities and neurodevelopmental difficulties worldwide. The rate of preterm births has been rising, in particular in Algeria. The purpose of this study is to determine the frequency of preterm births in the Oran Wilaya and to identify risk factors.

Methods

we used data from a multicentre cross-sectional study carried out in all Public Maternity Hospitals in the Oran Wilaya (13). The study included parturient women who had given birth to a live and/or stillborn child (with birthweights ≥500 g), whose gestational age was greater than or equal to 24-36 weeks of amenorrhoea. Mothers´ demographic, medical and socio-behavioural factors were recorded. Logistic regression was used to study predictors of prematurity.

Results

preterm birth rate was 9.9% (45/452). The average age of patients was 30.4±6 years; multiple pregnancies accounted for 2.2% of births. Factors related to prematurity were the risk of premature labour (aOR=4.68; 95% CI: 2.27-9.64), the lack of clinical monitoring of pregnancy (OR=2.83; CI 95%: 1.83-6.05) and gestational hypertension (aOR = 3.69, 95% CI: 1.83-8.8).

Conclusion

the rate of preterm births is in line with the rate observed in neighbouring countries. The study identified predictive factors, some of which are already targeted by the national perinatal program. However, it is essential to continue to lead efforts to improve the monitoring and management of pregnancies and premature births at all levels of care.

Occupational Exposure during Pregnancy and Effects on Newborns: A Nested Case-Control Study

BACKGROUND

The protection of pregnant workers should be based on evidence regarding the risks to reproductive health from exposure to specific work environments and conditions. The objective of this study was to identify the effects on mothers and newborns resulting from environmental exposure to various occupational risks.

METHODS

The study cohort was composed of 399 women admitted to the Obstetrics/Postpartum ward at Hospital La Fe in Valencia, Spain. Face-to-face interviews were conducted to establish associations between workplace exposure during pregnancy and its effects on maternal and newborn health. Sex, anthropometric characteristics, and blood gas analysis in arterial and venous umbilical cord blood at delivery were collected.

RESULTS

A total of 138 women were exposed to biological and/or chemical risks, 122 to physical risks, and 139 at no risk of exposure. In the group with chemical and/or biological risks, the frequency of women who resorted to in vitro fertilization to achieve the studied pregnancy is less than half of the group exposed to physical risks, with statistically significant differences (p = 0.047). The mean values for the arterial analysis in both exposure groups were within average values, with similar pH values between them, but the mean values of PCO2 and PO2 were lower in the group of neonates of mothers exposed to physical risks, with a significant difference for arterial PO2 (p = 0.027).

CONCLUSION

Our analysis contributes evidence for planning and prioritizing preventive actions to protect women's reproductive health. The results suggest the continuation of a future project that would consider more factors and potentially increase the sample size.

Maternal occupational exposure to organic solvents and intrauterine growth in the ELFE cohort

BACKGROUND

In developed countries, about 15% of women are occupationally exposed to solvents. Associations between this maternal occupational exposure and intrauterine fetal growth are inconsistent, but almost no existing study has investigated this relation by solvent family (oxygenated, petroleum, and chlorinated), although they may affect fetal growth differently.

OBJECTIVES

To investigate the relations between maternal occupational solvent exposure, by solvent family, and the risk of neonates born small for gestational age (SGA), or with low birthweight, or with small head circumference (HC).

METHODS

Among the 18,040 women enrolled in the Elfe rather than included in the Elfe birth cohort, we included 13,026 women who worked during pregnancy (72% of the cohort). Information about maternal occupations and industrial activities during pregnancy was collected by questionnaire at the maternity ward, and completed at 2-month when necessary. Using Matgéné job-exposure matrices, we assessed maternal occupational exposure to solvents. Logistic and multiple linear regressions were used to assess the association between maternal occupational solvent exposure and SGA status, birth weight, and HC. Analyses were conducted for exposure during pregnancy and also stratified by the trimester that pregnancy leave began.

RESULTS

We observed a higher risk of SGA newborns among mothers occupationally exposed during pregnancy to petroleum solvents (OR_adjusted = 1.26; 95%CI: 1.01 to 1.57). Among women working until the third trimester of pregnancy, we observed a higher risk of SGA newborns to those occupationally exposed to oxygenated solvents (OR_adjusted = 1.75; 95%CI: 1.11 to 2.75), a significantly lower birthweight for infants of mothers exposed to petroleum solvents (β_adjusted = -47.37 g; -89.33 to -5.42), and a lower HC among newborns of those occupationally exposed to oxygenated solvents (β_adjusted = -0.28; -0.49 to -0.07) and to chlorinated solvents (β_adjusted = -0.29; -0.53 to -0.05).

DISCUSSION

Our results suggest that maternal occupational solvent exposure may influence fetal growth, especially exposure into the third trimester of pregnancy.

Maternal environmental, occupational, and urinary metabolite levels of benzene compounds and their association with congenital heart diseases in offspring: a case‒control study in China

The conclusions about the association of maternal pregnancy environment, occupation, and benzene compounds with fetal CHD are not entirely consistent. Eight hundred seven CHD cases and 1008 controls were included in this study. All occupations were classified and coded against the Occupational Classification Dictionary of the People's Republic of China (2015 version). Logistic regressions were used to explore the correlation among environmental factors, occupation types, and CHDs in offspring. We found that living near public facilities and having exposure to chemical reagents and hazardous substances were significant risk factors for CHDs in offspring. We found that offspring of mothers who worked in agriculture and similar work during pregnancy suffered from CHD. The risk of all CHDs in the offspring of pregnant women working in production manufacturing and related work was significantly higher than that in unemployed pregnant women, the risk was also observed in 4 subtypes of CHDs. We compared the concentrations of the five metabolite (MA, mHA, HA, PGA, and SPMA) levels of benzene compounds in the urine of mothers in case and control groups and found no significant differences. Our study suggests that maternal exposure during pregnancy and certain environmental and occupational conditions are risk factors for CHD in offspring, but did not support an association between concentrations of metabolites of benzene compounds in the urine of pregnant women and CHDs in their offspring.

Women's occupational status during pregnancy and preventive behaviour and health outcomes between 1998 and 2016 in France

BACKGROUND

Despite an improvement in preventive care and perinatal health in previous decades, social inequalities persist, particularly to the disadvantage of isolated or unemployed women. The objective was to analyse the evolution between 1998 and 2016 of the association between women's occupational status and perinatal outcomes.

METHODS

Data came from four national surveys performed in 1998, 2003, 2010 and 2016. Occupational status was defined by maternal employment status and type of occupation during pregnancy. Preventive behaviours (initiation of antenatal care, antenatal classes, breast feeding) and health outcomes (hospitalization, preterm birth, birth weight below the 10th percentile) were analysed by occupational status adjusted for other maternal characteristics, for each study year.

RESULTS

The studied sample included 12,497 women in 1998, 13,290 in 2003, 13,209 in 2010 and 11,179 in 2016. The proportion of employed women increased from 66% to 75% between 1998 and 2016, and that of housewives decreased from 22% to 12%. The proportion of preterm births globally increased between 1998 and 2016, especially for housewives. The proportion of low birthweight for gestational age (LBWGA) remained similar over the years. From 1998 to 2016, the differences between occupational groups persisted for preterm births and LBWGA.

CONCLUSIONS

Occupational groups exhibited strong social differences in preventive care over the entire study period and persisted in the recent data. As a major social indicator, women's occupational status during pregnancy has to be considered as a risk factor of poor preventive behaviour and unfavourable perinatal outcomes.

Emission of Industrial Air Pollution and Mortality Due to Respiratory Diseases: A Birth Cohort Study in Poland

BACKGROUND

Air pollution is a major risk factor for public health worldwide, but evidence linking this environmental problem with the mortality of children in Central Europe is limited.

OBJECTIVE

To investigate the relationship between air pollution due to the emission of industry-related particulate matter and mortality due to respiratory diseases under one year of age.

METHODS

A retrospective birth cohort analysis of the dataset including 2,277,585 children from all Polish counties was conducted, and the dataset was matched with 248 deaths from respiratory diseases under one year of age. Time to death during the first 365 days of life was used as a dependent variable. Harmful emission was described as total particle pollution (TPP) from industries. The survival analysis was performed using the Cox proportional hazards model for the emission of TPP at the place of residence of the mother and child, adjusted individual characteristics, demographic factors, and socioeconomic status related to the contextual level.

RESULTS

Infants born in areas with extremely high emission of TPP had a significantly higher risk of mortality due to respiratory diseases: hazard ratio (HR) = 1.781 [95% confidence interval (CI): 1.175, 2.697], p = 0.006, compared with those born in areas with the lowest emission levels. This effect was persistent when significant factors were adjusted at individual and contextual levels (HR = 1.959 [95% CI: 1.058, 3.628], p = 0.032). The increased risk of mortality was marked between the 50th and 150th days of life, coinciding with the highest exposure to TPP.

CONCLUSIONS

The emission of TPP from industries is associated with mortality due to respiratory diseases under one year of age. A considerable proportion of children's deaths could be prevented in Poland, especially in urban areas, if air pollution due to the emission of particle pollution is reduced.

Maternal risk factors associated with term low birth weight in India: A review

Low birth weight is one of the leading factors for infant morbidity and mortality. To a large extent affect, various maternal risk factors are associated with pregnancy outcomes by increasing odds of delivering an infant with low birth weight. Despite this association, understanding the maternal risk factors affecting term low birth weight has been a challenging task. To date, limited studies have been conducted in India that exert independent magnitude of these effects on term low birth weight. The aim of this review is to examine the current knowledge of maternal risk factors that contribute to term low birth weight in the Indian population. In order to identify the potentially relevant articles, an extensive literature search was conducted using PubMed, Goggle Scholar and IndMed databases (1993 – Dec 2020). Our results indi­cate that maternal age, educational status, socio-economic status, ethnicity, parity, pre-pregnancy weight, maternal stature, maternal body mass index, obstetric history, maternal anaemia, gestational weight gain, short pregnancy outcome, hypertension during pregnancy, infection, antepartum haemorrhage, tobacco consumption, maternal occupation, maternal psychological stress, alcohol consumption, antenatal care and mid-upper arm circumference have all independent effects on term low birth weight in the Indian pop­ulation. Further, we argue that exploration for various other dimensions of maternal factors and underlying pathways can be useful for a better understanding of how it exerts independent association on term low birth weight in the Indian sub-continent.

Risk of adverse pregnancy outcomes by maternal occupational status: A national population-based study in South Korea

OBJECTIVE

This study examined the association between maternal occupational status and adverse pregnancy outcomes in the general South Korean population.

METHODS

We analyzed 1 825 845 employed and non-employed women with a diagnostic code for pregnancy in the National Health Insurance Service (NHIS) database (2010-2019) of South Korea. Based on their employment status and type of occupation, we calculated risk ratios for three adverse outcomes: early abortive outcomes (miscarriage, ectopic pregnancy, and molar pregnancy), stillbirth, and no live birth (diagnosis of pregnancy with no record of live birth thereafter, which include early abortive outcomes and stillbirth) with adjusting for covariates.

RESULTS

Overall, 18.0%, 0.7%, and 39.8% ended in early abortive outcomes, stillbirths, and no live births, respectively. The risk of early abortive outcomes and stillbirths was higher in non-employed women than in employed women, while no live births were more frequent in employed women. Those in the health and social work industry showed the highest risk of no live births. Manufacturing jobs (1.030, 95% CI: 1.013, 1.047) and health/social work (1.029, 95% CI: 1.012, 1.046) were associated with an increased risk of early abortive outcomes compared with financial and insurance jobs. Consistently higher risks of no live births were observed in the manufacturing, wholesale/retail trade, education, health/social work, and public/social/personal service occupation.

CONCLUSION

Employment during pregnancy and several occupation types were associated with a higher risk of pregnancy loss. Additional research using detailed job activity data is needed to determine specific occupational causes of adverse pregnancy outcomes.

Evaluation of a pilot consultation for maternity protection at work in Switzerland

STUDY AIMS

Switzerland's Labour Law and its Ordonnance on Maternity Protection aim to protect the health of pregnant employees and their unborn children while enabling them to continue to pursue their professional activities. Some companies encounter difficulties implementing the law's provisions. The Department of Occupational and Environmental Health, part of the Center for Primary Care and Public Health (Unisanté), has provided specialist occupational medicine consultations for pregnant employees since 2015. This study aimed to evaluate how well Swiss' maternity protection legislation is implemented by examining a list of relevant indicators measured during the occupational health consultation. The study also sought to investigate the consultation support provided to the relevant stakeholders and the adjustments made to pregnant employees' working conditions.

METHODS

Descriptive variables and indicators relative to the application of the Swiss maternity protection legislation for 83 pregnant employees were collected during the consultation's pilot phase (between 2015 and 2016). Descriptive statistics and cross-analyses of these indicators were made.

RESULTS

Most pregnant employees faced multiple exposures to occupational risks. Preventive risk analyses were rare. Few adjustments to workstations were proposed. We found a tendency for employees to leave their workstations early on in their pregnancies due to sick leave certificate prescriptions. Specialist consultation and collaboration with occupational health physicians to recommend interventions for pregnant employees can provide significant benefits and help some pregnant women to continue at their workstations with appropriate adjustments.

DISCUSSION

A specialised occupational health consultation is a useful instrument for identifying occupational hazards for both the pregnant woman and her unborn child. It is also an opportunity to explain employers' legal responsibilities and obligations to safeguard the health of their pregnant employees and to give specific advice for their company's situation. This consultation also enables employers to maintain their employees' valuable professional competencies in the workplace for as long as possible. Finally, occupational health consultation helps and supports healthcare providers who must, according to the law, make decisions about whether pregnant employees can continue working safely or not.

Maternal occupational exposures and fetal growth in a Spanish birth cohort

While the epidemiologic literature suggests certain maternal occupational exposures may be associated with reduced measures of size at birth, the occupational literature employing fetal biometry data to assess fetal growth is sparse. The present study examines associations between maternal occupational exposures and ultrasound-measured fetal growth. We included 1,739 singleton pregnancies from the INfancia y Medio Ambiente (INMA) project (2003-2008). At 32 weeks of pregnancy, interviewers ascertained mothers' employment status and assessed job-related physical loads, work schedules, and job strain during pregnancy. Job titles were linked to a job-exposure matrix to estimate exposure to 10 endocrine disrupting chemical (EDC) groups. We calculated z-scores from longitudinal growth curves representing trajectories from 0-12, 12-20 and 20-34 gestational weeks for abdominal circumference (AC), biparietal diameter (BPD), femur length (FL), and estimated fetal weight (EFW). Linear mixed models clustered by IMNA region (i.e., Gipuzkoa, Sabadell, Valencia) were used to examine associations between occupational exposures and fetal growth. Effect estimates are presented as percentage change in fetal growth. There was limited evidence of associations between work-related non-chemical stressors and fetal growth. We observed associations of similar magnitude between multiple EDC groups and decreased EFW trajectories during 20-34 gestational weeks (phthalates: -1.4% [-3.5, 0.6%]; alkylphenolic compounds (APCs): -1.1% [-2.3, 0.1%]; miscellaneous chemicals: -1.5% [-3.7, 0.8%]), while miscellaneous chemicals were associated with increased BPD from 12-20 weeks (2.1% [0.8, 3.5%]). Notably, 67% of women exposed to phthalates were hairdressers; 68% of women exposed to APCs worked as domestic cleaners. In conclusion, we found limited evidence that maternal occupational exposures impact fetal growth. Further research should consider the combined impact of multiple workplace exposures.

Midwives and protection of pregnant workers in Western Switzerland: Practices, difficulties and contributions

BACKGROUND

Switzerland's maternity protection legislation aims to protect the health of pregnant employees and their unborn children by regulating their potential occupational exposure to hazards and strenuous activities. This legislation provides a role for obstetricians, but not for midwives.

AIMS

Identify the practices of Switzerland's French-speaking midwives that favour the implementation of maternity protection legislation and reflect on the profession's role in supporting pregnant employees.

METHODS

356 midwives answered an online questionnaire. The analysis focuses on the 205 midwives who perform pregnancy consultations in their practice. Data were analysed in two stages using STATA software: 1) simple descriptive and correlational statistics and 2) hierarchical cluster analysis to identify typologies of practices by grouping similar responses.

FINDINGS

Despite having no officially defined role in Switzerland's maternity protection legislation, its midwives actively participate in protecting pregnant employees , especially those with more knowledge of the legislation, those with more years of experience and those practicing independently. The barriers that midwives face when trying to provide greater support for pregnant employees are linked significantly to their lack of knowledge about the legislation, a lack of recognition for their role in the current legislation and a lack of continuing education about the occupational health risks associated with pregnancy at work.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Their profession and specific practices give midwives privileged access to pregnant employees. Midwives' knowledge of the legislation, their awareness of the occupational risks and hazards facing pregnant employees and the conviction that their profession has the potential to make a difference could all be improved. The role of midwives should be-and deserves to be-formally and legally recognised and integrated into Switzerland's maternity protection legislation.

The Health Care Provider's Role in Securing Work Accommodations for Pregnant and Postpartum Patients

Most women today are the primary, sole, or cobreadwinners for their families; their continued ability to work during and after pregnancy is crucial for their families' well-being. Midwives and other health care providers are regularly asked to provide work notes for patients who need adjustments to how, when, or where their job is done to continue working while maintaining a healthy pregnancy or breastfeeding. Whereas an improperly written work note can result in the patient being forced out on leave or losing their job, an effectively written work note from a health care provider can ensure the patient will receive the adjustments they need to stay safe and healthy on the job. Health care providers can also play an important role by incorporating discussions about workplace issues into care conversations. This article provides an overview of pregnancy-related employment rights, guidelines for writing effective work notes, and a discussion of common workplace issues patients face and how health care providers can respond.

Disparities in the usage of maternity leave according to occupation, race/ethnicity, and education

BACKGROUND

Unlike almost all other countries, the United States does not mandate paid maternity leave for mothers. Lack of access to maternity leave may be a risk factor for adverse maternal and child health outcomes. This study sought to assess disparities in the usage of maternity leave according to maternal occupation, race/ethnicity, and education, and to explore the relationships between these factors.

METHODS

We used data from the Pregnancy Risk Assessment Monitoring System from the years 2016 and 2017. We calculated the prevalence of usage of maternity leave and paid maternity leave according to the mother's age, race/ethnicity, education, state, and occupation. We constructed regression models to explore the bivariate and mutually adjusted associations between these factors and usage of maternal leave.

RESULTS

Usage of maternity leave and paid maternity leave were estimated at 89.3% and 49.0%, respectively. Usage of paid maternity leave was lower in younger mothers, in Black and Hispanic mothers, and in mothers with fewer years of education. Workers in several occupations, including building and grounds cleaning and maintenance, personal care, and food preparation and serving, used maternity leave at rates significantly lower than the average of all workers. Adjustment for education and occupation reduced, but did not obviate, racial/ethnic differentials in usage of paid maternity leave.

CONCLUSIONS

There are substantial differentials in usage of maternity leave. Further research could examine whether these differences contribute to disparities in maternal and child health outcomes.

Quantile regression analysis of the socioeconomic inequalities in air pollution and birth weight

BACKGROUND

An association between maternal exposure to air pollution and the birth weight distribution has been reported, but the extent to which this relationship varies according to socioeconomic status (SES) is unknown. This study examined the relationship using the data from a Korean birth cohort.

METHODS

Data for singleton births in Seoul from 2007 to 2017 (n = 1739) were analyzed. Maternal exposures to particulate matter with an aerodynamic diameter <10 µm (PM₁₀) and <2.5 µm (PM_2.5), as well as to nitrogen dioxide (NO₂) and ozone (O₃) for each trimester and the entire pregnancy were estimated using residential address, gestational age, and the birth date. The associations between the interquartile range (IQR) increases in pollutant concentrations and the changes in birth weight were examined using linear regression and quantile regression models. The socioeconomic disparities in the associations were investigated using a derived SES variable based on the composite of parental education and occupation. This SES variable was then interacted with the air pollutant.

RESULTS

In the gestational age-adjusted models, particulate air pollutants (PM₁₀ and PM_2.5) and O₃ were associated with birth weight decreases for the lower birth weight percentiles. For example, the decrease in mean birthweight per IQR increase in PM_2.5 during second trimester was -21.1 g (95% confidence interval (CI) = -41.8, -0.4), whereas the quantile-specific associations were: 10th percentile -27.0 g (95% CI = -46.6, -7.3); 50th percentile -22.2 g (95% CI = -39.6, -4.8); and 90th percentile -22.9 g (95% CI = -45.5, -0.2). Particulate air pollutants and O₃ showed a pattern of socioeconomic inequalities; the reduced birth weight was of greater magnitude for children from a low SES group.

CONCLUSIONS

Negative associations between particulate air pollutants and O₃ and birth weight were consistently greater at the lower quantiles of the birth weight distribution, especially in lower SES group.

Maternal Work and Spontaneous Preterm Birth: A Multicenter Observational Study in Brazil

Spontaneous preterm birth (sPTB) is a major pregnancy complication involving biological, social, behavioural and environmental mechanisms. Workload, shift and intensity may play a role in the occurrence of sPTB. This analysis is aimed addressing the effect of occupational activities on the risk for sPTB and the related outcomes. We conducted a secondary analysis of the EMIP study, a Brazilian multicentre cross-sectional study. For this analysis, we included 1,280 singleton sPTB and 1,136 singleton term birth cases. Independent variables included sociodemographic characteristics, clinical complications, work characteristics, and physical effort devoted to household chores. A backward multiple logistic regression analysis was applied for a model using work characteristics, controlled by cluster sampling design. On bivariate analysis, discontinuing work during pregnancy and working until the 7^th month of pregnancy were risks for premature birth while working during the 8^th - 9^th month of pregnancy, prolonged standing during work and doing household chores appeared to be protective against sPTB during pregnancy. Previous preterm birth, polyhydramnios, vaginal bleeding, stopping work during pregnancy, or working until the 7^th month of pregnancy were risk factors in the multivariate analysis. The protective effect of variables compatible with exertion during paid work may represent a reverse causality. Nevertheless, a reduced risk associated with household duties, and working until the 8^th-9^th month of pregnancy support the hypothesis that some sort of physical exertion may provide actual protection against sPTB.

Implementation of maternity protection legislation: Gynecologists' perceptions and practices in French-speaking Switzerland

Background

In several countries, maternity protection legislations (MPL) confer an essential role to gynecologist-obstetricians (OBGYNs) for the protection of pregnant workers and their future children from occupational exposures. This study explores OBGYNs’ practices and difficulties in implementing MPL in the French-speaking part of Switzerland.

Methods

An online survey was sent to 333 OBGYNs. Data analysis included: 1) descriptive and correlational statistics and 2) hierarchical cluster analysis to identify patterns of practices.

Results

OBGYNs evoked several problems in MPL implementation: absence of risk analysis in the companies, difficult collaboration with employers, lack of competencies in the field of occupational health. Preventive leave was underused, with sick leave being prescribed instead. Training had a positive effect on OBGYNs’ knowledge and implementation of MPL. Hierarchical cluster analysis highlighted three main types of practices: 1) practice in line with legislation; 2) practice on a case-by-case basis; 3) limited practice. OBGYNs with good knowledge of MPL more consistently applied its provisions.

Conclusion

The implementation of MPL appears challenging for OBGYNs. Collaboration with occupational physicians and training might help OBGYNs to better take on their role in maternity protection. MPL in itself could be improved.

Retrospective cohort study of the association between maternal employment precarity and infant low birth weight in women in the USA

OBJECTIVES

To investigate the association between maternal employment precarity and infant low birth weight (LBW), and to assess if this association differs by race/ethnicity.

METHODS

Data were collected from 2871 women enrolled in the National Longitudinal Survey of Youth 1979 and the National Longitudinal Survey of Youth 1979 Children and Young Adult Cohort. Employment precarity was evaluated using a summary variable that combined several employment attributes: availability of employer-sponsored insurance, income, long shifts, non-daytime shifts, availability of employer sponsored training or educational benefits and membership in a union or collective bargaining unit. Employment precarity scores (a sum of the number of negative employment attributes) were categorised into low (0-2), medium (3) and high (4-6). LBW was defined as weight less than 2500 g at birth. Modified Poisson models were fit to calculate risk ratios and 95% CIs and adjusted for maternal age, race/ethnicity, educational attainment, nativity, prepregnancy body mass index, alcohol consumption, smoking during pregnancy and infant year of birth. We assessed effect modification by maternal race/ethnicity using a composite exposure-race variable.

RESULTS

Women with high employment precarity had higher risk of a LBW delivery compared with women with low employment precarity (RR: 1.48, 95% CI: 1.11 to 1.98). Compared to non-Hispanic/non-black women with low employment precarity, non-Hispanic black women (RR: 2.68; 95% CI: 1.72 to 4.15), Hispanic women (RR: 2.53; 95% CI: 1.54 to 4.16) and non-Hispanic/non-black women (RR: 1.46; 95% CI: 0.98 to 2.16) with high employment precarity had higher risk of LBW.

CONCLUSIONS

We observed higher risk of LBW in pregnancies of women with high employment precarity; this association was stronger among black and Hispanic mothers compared to non-Hispanic/non-black women. Findings of this study can be used to inform antenatal care and identify workplace policies to better support women who work during pregnancy.

Maternal cumulative exposure to extremely low frequency electromagnetic fields, prematurity and small for gestational age: a pooled analysis of two birth cohorts

Background

Data on the effects of extremely low frequency electromagnetic fields (ELF-EMF) on pregnancy outcomes are inconclusive.

Objective

To study the relation between maternal cumulative exposure to ELF-EMF during pregnancy and the risk of prematurity or small for gestational age (SGA) in a pooled analysis of two French birth cohorts.

Methods

Elfe and Epipage2 are both population-based birth cohorts initiated in 2011 and included 18 329 and 8400 births, respectively. Health data and household, mother and child characteristics were obtained from medical records and questionnaires at maternity and during follow-up. A job exposure matrix was used to assess cumulative exposure to ELF-EMF during three periods: (1) until 15 weeks of gestation, (2) until 28 weeks of gestation and (3) until 32 weeks of gestation. Analyses were restricted to single live births in mainland France and to mothers with documented jobs (N=19 894). Adjusted logistic regression models were used.

Results

According to the period studied, 3.2%–4% of mothers were classified as highly exposed. Results were heterogeneous. Increased risks of prematurity were found among low exposed mothers for the three periods, and no association was observed among the most exposed (OR1=0.92 (95% CI 0.74 to 1.15); OR2=0.98 (95% CI 0.80 to 1.21); OR3=1.14 (95% CI 0.92 to 1.41)). For SGA, no association was observed with the exception of increased risk among the low exposed mothers in period 2 and the most exposed in period 3 (OR=1.25 (95% CI 1.02 to 1.53)).

Conclusion

Some heterogeneous associations between ELF-EMF exposure and prematurity and SGA were observed. However, due to heterogeneity (ie, their independence regarding the level of exposure), associations cannot be definitely explained by ELF-EMF exposure.

ACOG Committee Opinion No. 733: Employment Considerations During Pregnancy and the Postpartum Period

In the United States, it is common for women, including mothers and pregnant women, to work outside the home. Working during pregnancy is generally safe. For those in high-risk occupations or with medically complicated pregnancies, work accommodations often can allow for continued safe employment. The major employment issues concerning pregnant women include pregnancy-related discrimination, work accommodations that allow continued employment, job-protected leave, and wage replacement while on leave. Workplace discrimination related to being pregnant and pregnancy-related harassment, including discrimination in the hiring process, is prohibited by federal and state law. There is no federal law guaranteeing comprehensive accommodations for pregnant and postpartum workers. Current federal and state laws provide protection for some pregnant women, but not others, because of eligibility requirements and state-by-state differences. By writing appropriate notes to employers, obstetrician-gynecologists and other obstetric care providers can be instrumental in obtaining accommodations for their patients who are able to continue working. Accommodations that allow a woman to keep working are the most reliable way to guarantee pay, benefits, and job protection. Obstetrician-gynecologists and other obstetric care providers also can assist pregnant women and their partners by providing them with information and resources that might help them better understand their employment rights. However, in cases for which potential job discrimination has occurred, accommodations are denied, extended medical leave is necessary, or when other complex employment questions arise, legal assistance should be obtained.

Demographic surveillance over 12 years helps elicit determinants of low birth weights in India

BACKGROUND

Low birth weight is an important predictor of maternal and child health. Birth weight is likely to be affected by maternal health, socioeconomic status and quality of health care facilities.

OBJECTIVE

To assess trends in the birth weight, the proportion of low birth weight, maternal factors and health care facilities for delivery in villages of Western Maharashtra from the year 2004 to 2016 and to analyze factors associated with low birth weight for total birth data of 2004-2016.

METHODS

Data collected for 19244 births from 22 villages in Vadu Health and Demographic Surveillance System (HDSS), Pune, Maharashtra, India from the year 2004 to 2016 were used for this analysis.

RESULTS

There was an overall increase in the annual mean birth weight from 2640.12 gram [95% CI 2602.21-2686.84] in the year 2004 to 2781.19 gram [95% CI 2749.49-2797.95] in the year 2016. There was no secular trend to show increase or decrease in the proportion of low weight at birth. Increasing maternal age (>18 years) compounded with better education, reduced parity and increasing number of institutional deliveries were significant trends observed during the past decade. Low birth weight was found to be associated with female gender, first birth order, poor maternal education and occupation as cultivation.

CONCLUSION

Changes in maternal age, education, occupation, and increased institutionalized deliveries contributed in to increasing birth weights in rural Maharashtra. Female gender, first birth order, poor maternal education and occupation of cultivation are associated with increased risk of low birth weight.

Socioeconomic position during pregnancy and DNA methylation signatures at three stages across early life: epigenome-wide association studies in the ALSPAC birth cohort

BACKGROUND

Socioeconomic experiences are recognized determinants of health, and recent work has shown that social disadvantages in early life may induce sustained biological changes at molecular level that are detectable later in life. However, the dynamics and persistence of biological embedding of socioeconomic position (SEP) remains vastly unexplored.

METHODS

Using the data from the ALSPAC birth cohort, we performed epigenome-wide association studies of DNA methylation changes at three life stages (birth, n = 914; childhood at mean age 7.5 years, n = 973; and adolescence at mean age 15.5 years, n = 974), measured using the Illumina HumanMethylation450 Beadchip, in relation to pregnancy SEP indicators (maternal and paternal education and occupation).

RESULTS

Across the four early life SEP metrics investigated, only maternal education was associated with methylation levels at birth, and four CpGs mapped to SULF1, GLB1L2 and RPUSD1 genes were identified [false discovery rate (FDR)-corrected P-value <0.05]. No epigenetic signature was found associated with maternal education in child samples, but methylation levels at 20 CpG loci were found significantly associated with maternal education in adolescence. Although no overlap was found between the differentially methylated CpG sites at different ages, we identified two CpG sites at birth and during adolescence which are 219 bp apart in the SULF1 gene that encodes an heparan sulphatase involved in modulation of signalling pathways. Using data from an independent birth cohort, the ENVIRONAGE cohort, we were not able to replicate these findings.

CONCLUSIONS

Taken together, our results suggest that parental SEP, and particularly maternal education, may influence the offspring's methylome at birth and adolescence.

Maternal occupational exposures to nanoscale particles and small for gestational age outcome in the French Longitudinal Study of Children

OBJECTIVES

To investigate the association between maternal occupational exposures to nanoscale particles (NPs) during pregnancy and small for gestational age (SGA).

METHODS

This study included 11,224 mothers and singleton birth pairs from the French Longitudinal Study of Children (ELFE cohort), which included infants born after 33 weeks of gestation or more in continental France in 2011. Mothers who did not work during pregnancy were excluded from the analyses. Maternal occupational exposures to NPs was estimated using a job-exposure matrix for the probability (>50%: occupationally exposed group, n = 569; 0%: occupationally non-exposed group, n = 9113; between these two thresholds: uncertain group, n = 1542) and frequency of exposure. Associations were estimated from multivariate logistic regression models for occupationally exposed vs occupationally unexposed groups in a first analysis, and with the frequency-weighted duration of work for the occupationally exposed group only in a second analysis.

RESULTS

Among working mothers, 5.1% were occupationally exposed to NPs. Maternal occupational exposures to NPs was associated with SGA (ORa = 1.63, 95% CI: 1.22, 2.18). The frequency-weighted duration of work for the occupationally exposed group (n = 569) was not associated with SGA (ORa = 1.02, 95% CI: 0.97, 1.08) in adjusted analyses.

CONCLUSIONS

These results, showing a significant association between occupational exposures to NPs and SGA, should encourage further studies to examine the adverse effect of NPs exposure on fetal development.

Influence of paid maternity leave on return to work after childbirth

BACKGROUND

Paid maternity leave (ML) has been associated with better health outcomes in mothers and newborns. However, its protective role in mothers' employment after childbirth remains unclear.

OBJECTIVE

To assess the association between paid ML and being employed 1-year after childbirth.

METHODS

As part of the INfancia y Medio Ambiente (INMA) cohort study, 507 Spanish women employed at 12th week of pregnancy, were asked about their employment status and job characteristics at 32nd week of pregnancy. One year after childbirth, they were re-interviewed about their employment status and if they had taken paid ML. Incidence of maternal employment 1-year after childbirth was estimated. Crude and adjusted associations with paid ML were assessed by logistic regression, and characterized by odds ratios (ORs) with associated 95% CIs.

RESULTS

Information was obtained from 398 women. Of those, 290 (72.9%) were employed 1-year after childbirth. Incidence of maternal employment was lower for those who: i) didn't take paid ML, ii) were younger than 27 years; iii) had temporary contract, iv) had part-time jobs, v) reported less-favoured familiar social class, and vi) left the job before 32 weeks of pregnancy. Being employed 1-year after childbirth was more common in those who took paid ML (OR 2.7, 95%CI 1.6-4.5), also after adjusting for staying at work until advanced stages of pregnancy (OR 1.8, 95%CI 1.0-3.1).

CONCLUSIONS

Taking paid ML seems to be associated with higher maternal employment rates 1-year after childbirth. Therefore, our findings suggest that protection of maternity might positively influence women's labour market participation after childbirth.

Paid Family Leave to Enhance the Health Outcomes of Preterm Infants

Prematurity is the largest contributor to perinatal morbidity and mortality. Preterm infants and their families are a significant vulnerable population burdened with limited resources, numerous health risks, and poor health outcomes. The social determinants of health greatly shape the economic and psychosocial resources that families possess to promote optimal outcomes for their preterm infants. The purposes of this article are to analyze the resource availability, relative risks, and health outcomes of preterm infants and their families and to discuss why universal paid family leave could be one potential public policy that would promote optimal outcomes for this infant population. First, we discuss the history of family leave in the United States and draw comparisons with other countries around the world. We use the vulnerable populations conceptual model as a framework to discuss why universal paid family leave is needed and to review how disparities in resource availability are driving the health status of preterm infants. We conclude with implications for research, nursing practice, and public policy. Although health care providers, policy makers, and other key stakeholders have paid considerable attention to and allocated resources for preventing and treating prematurity, this attention is geared toward individual-based health strategies for promoting preconception health, preventing a preterm birth, and improving individual infant outcomes. Our view is that public policies addressing the social determinants of health (e.g., universal paid family leave) would have a much greater impact on the health outcomes of preterm infants and their families than current strategies.

Personal Oral Infection Control, Low Birthweight, and Preterm Births in Appalachia West Virginia: A Cross-Sectional Study

INTRODUCTION

Appalachia West Virginia has a higher prevalence of preterm and low birthweight babies than the US national prevalence. Many factors have been studied which are known to influence preterm births and low birthweight babies. There are limited interventions that are available to decrease the likelihood of preterm and low birthweight babies; however oral health and personal oral infection control may be helpful. The purpose of this study was to evaluate the association of limited personal oral infection control among pregnant West Virginia Appalachian women and poor birth outcomes (preterm and low birthweight babies).

METHODS

A secondary data analysis of data from the West Virginia Healthy Start Helping Appalachian Parents and Infants (HAPI) Project from 2005 to 2016 was conducted. The researchers determined the odds ratio of personal oral infection control with a powered toothbrush (use of the brush fewer than 13 times per week versus use of the brush 13 or more times per week) on poor birth outcomes.

RESULTS

There were 845 women who completed the oral health program within the HAPI project. In unadjusted logistic regression, women who used the powered toothbrush and brushed less frequently had greater odds of poor birth outcomes than women who brushed more frequently (odds ratio of 2.07 [1.18, 3.62] P = 0.011 for low birthweight babies; and an odds ratio of 1.78 [1.04, 3.02] P = 0.034 for preterm birth). The results remained positive but were no longer significant in adjusted analysis.

CONCLUSION

There is a need to identify interventions that will benefit pregnant women so that their pregnancies result in healthy pregnancy outcomes.

Associations between birth outcomes and maternal PM2.5 exposure in Shanghai: A comparison of three exposure assessment approaches

BACKGROUND

Few studies have estimated effects of maternal PM_2.5 exposure on birth outcomes in China due to the lack of historical air pollution data.

OBJECTIVES

We estimated the associations between maternal PM_2.5 exposure and birth outcomes using gap-filled satellite estimates in Shanghai, China.

METHODS

We obtained birth registration records of 132,783 singleton live births during 2011-2014 in Shanghai. PM_2.5 exposures were assessed from satellite-derived estimates or central-site measurements. Linear and logistic regressions were used to estimate associations with term birth weight and term low birth weight (LBW), respectively. Logistic and discrete-time survival models were used to estimate associations with preterm birth. Effect modification by maternal age and parental education levels was investigated.

RESULTS

A 10 μg/m³ increase in gap-filled satellite-based whole-pregnancy PM_2.5 exposure was associated with a -12.85 g (95% CI: -18.44, -7.27) change in term birth weight, increased risk of preterm birth (OR 1.27, 95% CI: 1.20, 1.36), and increased risk of term LBW (OR 1.22, 95% CI: 1.06, 1.41). Sensitivity analyses during 2013-2014, when ground PM_2.5 measurements were available, showed that the health associations using gap-filled satellite PM_2.5 concentrations were higher than those obtained using satellite PM_2.5 concentrations without accounting for missingness. The health associations using gap-filled satellite PM_2.5 had similar magnitudes to those using central-site measurements, but with narrower confidence intervals.

CONCLUSIONS

The magnitude of associations between maternal PM_2.5 exposure and adverse birth outcomes in Shanghai was higher than previous findings. One reason could be reduced exposure error of the gap-filled high-resolution satellite PM_2.5 estimates.

Environmental health surveillance in a future European health information system

BACKGROUND

To date Health information (HI) in the European Union does not comprise indicators or other information related to impacts of hazardous chemicals in consumer products, food, drinking water or air on the health status of the population. Therefore, we inventorised and evaluated the potential of environmental health surveillance and research data sources in the European population to provide HBM-based indicators of internal human exposure and health impact of relevant chemicals.

METHODS

We established an up-dated inventory of European cross-sectional Human Biomonitoring (HBM) surveys and of birth cohorts, and compared chemicals and chemical groups addressed by HBM with indicators and health end points collected via European Core Health Indicators (ECHI), in birth registries, as well as in environmental and food data bases and health registries to see on how data collection could be aligned. Finally, we investigated study designs of HBM survey and health examination surveys for potential synergies.

RESULTS

The inventory covers a total of 11 European cross-sectional national programmes and a large number of birth cohorts and includes information on study population, age groups, covered substances, sampled matrices, and frequency. The comparison of data collections shows that there are many overlaps between environmental chemicals with environmental and health reporting. HBM data could be linked with ECHI indicators for work-related risks, body mass index (BMI), and low birth weight, with perinatal disease, neurologic disorders, and some chronic diseases, or with data bases for e.g. indoor air, food, or consumer products. Existing initiatives to link data collections at European Environment Agency (EEA) and Joint Research Center (JRC) or at World Health Organization (WHO) are good options to further develop linkage of HBM with exposures sources and health end points.

CONCLUSIONS

There is potential to use HBM based information in a number of public health policies, and this would help to align reporting to international commitments. Environmental health surveillance based on HBM and HBM-based indicators, is an excellent tool to inform public health policies about risks from environmental chemicals, and the EU health information system would benefit from additional HBM-based indicators for monitoring exposure burden from environmental chemicals. Considerable efforts are needed to align and establish routine data collections and to develop a surveillance system and indicators which may inform public health policies.

[Occupational risk during pregnancy and sick leave in a cohort of workers from Parc de Salut Mar (Barcelona, Spain)]

OBJECTIVE

To study the use of the Pregnancy occupational risk benefit (PORB) and non-work related sickness absence (NWSA) in a cohort of pregnant workers of Parc de Salut Mar, Barcelona (Spain).

METHOD

Retrospective cohort study of 428 pregnant workers between 2010 and 2014, who were followed-up until delivery. Absences from work, both PORB and NWSA were recorded until the beginning of their maternity leave. The sequence analysis identifies four trajectories, which are described according to workers demographic and job characteristics.

RESULTS

Of the total cohort, 56 (13.1%) accessed only the PORB, representing 6.126 days of absence; 68 (15.9%) also accessed PORB, with 7.127 days of absence, but had previously accumulated 102 episodes of NWSA with 1.820 days of absence. The majority of pregnant workers in the sample (69.9%) took only one or several episodes of NWSA without using PORB, with 545 episodes and 26,337 days of absence. Most were active during the first quarter and it is from the second quarter that episodes of long-term NWSA appeared. During the last month of pregnancy more than 80% of the workers were absent from work.

CONCLUSIONS

Pregnant workers remained at work for two thirds of their pregnancy. Absences were mainly due to episodes of NWSA. PORB represented one third of them. As in other similar countries, our results suggest a change in the management of social protection benefits for pregnant workers.

Protection of pregnant women at work in Switzerland: practices, obstacles and resources. A mixed-methods study protocol

INTRODUCTION

Like most industrialised countries, Switzerland has introduced legislation to protect the health of pregnant workers and their unborn children from workplace exposure. This legislation provides for a risk assessment, adaptations to workplaces and, if the danger is not eliminated, preventive leave (prescribed by a gynaecologist). This study's first objective is to analyse the degree to which companies, gynaecologists and midwives implement the law. Its second objective is to understand the obstacles and resources of this implementation, with a focus on how relevant stakeholders perceive protective measures and their involvement with them.

METHODS AND ANALYSIS

Data will be collected using mixed methods: (1) online questionnaires for gynaecologists and midwives; telephone questionnaires with company human resources (HR) managers in the healthcare and food production sectors; (2a) case studies of 6-8 companies in each sector, including interviews with stakeholders such as women workers, HR managers and occupational health physicians; (2b) two focus groups, one involving occupational physicians and hygienists, one involving labour inspectors.Quantitative data will be analysed statistically using STATA software V.15. Qualitative data will be transcribed and thematically analysed using MaxQDA software.

ETHICS AND DISSEMINATION

The Human Research Ethics Committee of the Canton Vaud (CER-VD) has certified that this research study protocol falls outside of the field of application of the Swiss Federal Act on Research Involving Humans.The publications and recommendations resulting from this study will form the starting point for future improvements to the protection of pregnant women at work and their unborn children.This study started in February 2017 and will continue until January 2020.

Maternal cumulative exposure to extremely low frequency electromagnetic fields and pregnancy outcomes in the Elfe cohort

OBJECTIVES

To study the relations between maternal cumulative exposure to extremely low frequency electromagnetic fields (ELF EMF) and the risk of moderate prematurity and small for gestational age within the Elfe cohort.

METHODS

The Elfe study included 18,329 infants born at 33weeks of gestation or more in France in 2011 and was designed to follow the children until 20years of age. Gestational age and anthropometric data at birth were collected in medical records and small for gestational age was defined according to a French customized growth standard. During interviews, mothers were asked to report their job status during pregnancy. If employed, their occupation was coded according to the International Standard Classification of Occupations 1988 and the date on which they stopped their work was recorded. Cumulative exposure to ELF EMF during pregnancy was assessed, for both mothers who worked and those who did not during pregnancy, using a recently-updated job-exposure matrix (JEM). Cumulative exposure was considered as a categorical variable (<17.5, 17.5-23.8, 23.8-36.2, 36.2-61.6 or ≥61.6μT-days), a binary variable (<44.1 and ≥44.1μT-days) and a continuous variable. Associations were analyzed by logistic regression, adjusting for the mother's lifestyle factors, sociodemographic characteristics and some mother's medical history during and before pregnancy. Analyses were restricted to single births and to complete values for the pregnancy outcomes (n=16,733).

RESULTS

Cumulative exposure was obtained for 96.0% of the mothers. Among them, 37.5% were classified in the 23.8-36.2μT-days category, but high exposures were rare: 1.3% in the ≥61.6μT-days category and 5.5% in the ≥44.1μT-days category. No significant association was observed between maternal cumulative exposure and moderate prematurity and small for gestational age in this exposure range.

CONCLUSION

This large population-based study does not suggest that maternal exposure to ELF EMF during pregnancy is highly associated with risks of moderate prematurity or small for gestational age.

Social correlates of term small for gestational age babies in a Russian Arctic setting

BACKGROUND

Small for gestational age (SGA) births have been associated with both short- and long-term adverse health outcomes. Although social risk factors for SGA births have been studied earlier, such data are limited from Northern Russia.

OBJECTIVE

We assessed maternal social risk factors for term SGA births based on data from the population-based Murmansk County Birth Registry (MCBR).

DESIGN

Data on term live-born singleton infants born between 2006 and 2011 in Murmansk County were obtained from the MCBR. We applied the 10th percentile for only birth weight (SGAW) or for both birth weight and birth length (SGAWL). Binary logistic regression was used to estimate the effect of independent variables on SGA males and females with adjustment for known risk factors and potential confounders. Both crude and adjusted odds ratios with 95% confidence intervals for the studied risk factors were calculated.

RESULTS

The proportions of term SGAW and SGAWL births were 9.7 and 4.1%, respectively. After adjustment for potential confounders, the risk of term SGA births among less educated, unemployed, unmarried, smoking and underweight women was higher compared with women from the reference groups. Evidence of alcohol abuse was also associated with birth of SGAWL and SGAW boys. Maternal overweight and obesity decreased the risk of SGA.

CONCLUSIONS

Maternal low education, unemployment, unmarried status, smoking, evidence of alcohol abuse and underweight increased the risk of term SGA births in a Russian Arctic setting. This emphasizes the importance of both social and lifestyle factors for pregnancy outcomes. Public health efforts to reduce smoking, alcohol consumption and underweight of pregnant women may therefore promote a decrease in the prevalence of SGA births.

Occupational Exposure to Endocrine-Disrupting Chemicals and Birth Weight and Length of Gestation: A European Meta-Analysis

BACKGROUND

Women of reproductive age can be exposed to endocrine-disrupting chemicals (EDCs) at work, and exposure to EDCs in pregnancy may affect fetal growth.

OBJECTIVES

We assessed whether maternal occupational exposure to EDCs during pregnancy as classified by application of a job exposure matrix was associated with birth weight, term low birth weight (LBW), length of gestation, and preterm delivery.

METHODS

Using individual participant data from 133,957 mother-child pairs in 13 European cohorts spanning births from 1994 through 2011, we linked maternal job titles with exposure to 10 EDC groups as assessed through a job exposure matrix. For each group, we combined the two levels of exposure categories (possible and probable) and compared birth outcomes with the unexposed group (exposure unlikely). We performed meta-analyses of cohort-specific estimates.

RESULTS

Eleven percent of pregnant women were classified as exposed to EDCs at work during pregnancy, based on job title. Classification of exposure to one or more EDC group was associated with an increased risk of term LBW [odds ratio (OR) = 1.25; 95% CI: 1.04, 1.49], as were most specific EDC groups; this association was consistent across cohorts. Further, the risk increased with increasing number of EDC groups (OR = 2.11; 95% CI: 1.10, 4.06 for exposure to four or more EDC groups). There were few associations (p < 0.05) with the other outcomes; women holding job titles classified as exposed to bisphenol A or brominated flame retardants were at higher risk for longer length of gestation.

CONCLUSION

Results from our large population-based birth cohort design indicate that employment during pregnancy in occupations classified as possibly or probably exposed to EDCs was associated with an increased risk of term LBW. Citation: Birks L, Casas M, Garcia AM, Alexander J, Barros H, Bergström A, Bonde JP, Burdorf A, Costet N, Danileviciute A, Eggesbø M, Fernández MF, González-Galarzo MC, Gražulevičienė R, Hanke W, Jaddoe V, Kogevinas M, Kull I, Lertxundi A, Melaki V, Andersen AM, Olea N, Polanska K, Rusconi F, Santa-Marina L, Santos AC, Vrijkotte T, Zugna D, Nieuwenhuijsen M, Cordier S, Vrijheid M. 2016. Occupational exposure to endocrine-disrupting chemicals and birth weight and length of gestation: a European meta-analysis. Environ Health Perspect 124:1785-1793; http://dx.doi.org/10.1289/EHP208.

[Epidemiology and risk factors of preterm birth]

OBJECTIVE

To synthesize the available evidence regarding the incidence and several risk factors of preterm birth. To describe neonatal outcomes according to gestational age and to the context of delivery.

MATERIALS AND METHODS

Consultation of the Medline database.

RESULTS

In 2010, 11% of live births (15 million babies) occurred before 37 completed weeks of gestation worldwide. About 85% of these births were moderate to late preterm babies (32-36 weeks), 10% were very preterm babies (28-31 weeks) and 5% were extremely preterm babies (<28 weeks). In France, premature birth concerns 60,000 neonates every year, 12,000 of whom are born before 32 completed weeks of gestation. Half of them are delivered after spontaneous onset of labor or preterm premature rupture of the membranes, and the other half are provider-initiated preterm births. Several maternal factors are associated with preterm birth, including sociodemographic, obstetrical, psychological, and genetic factors; paternal and environmental factors are also involved. Gestational age is highly associated with neonatal mortality and with short- and long-term morbidities. Pregnancy complications and the context of delivery also have an impact on neonatal outcomes.

CONCLUSION

Preterm birth is one of the leading cause of the under-five mortality and of neurodevelopmental impairment worldwide; it remains a major public health issue.

Cohort profile: cerebral palsy in the Norwegian and Danish birth cohorts (MOBAND-CP)

PURPOSE

The purpose of MOthers and BAbies in Norway and Denmark cerebral palsy (MOBAND-CP) was to study CP aetiology in a prospective design.

PARTICIPANTS

MOBAND-CP is a cohort of more than 210 000 children, created as a collaboration between the world's two largest pregnancy cohorts-the Norwegian Mother and Child Cohort study (MoBa) and the Danish National Birth Cohort. MOBAND-CP includes maternal interview/questionnaire data collected during pregnancy and follow-up, plus linked information from national health registries.

FINDINGS TO DATE

Initial harmonisation of data from the 2 cohorts has created 140 variables for children and their mothers. In the MOBAND-CP cohort, 438 children with CP have been identified through record linkage with validated national registries, providing by far the largest such sample with prospectively collected detailed pregnancy data. Several studies investigating various hypotheses regarding CP aetiology are currently on-going.

FUTURE PLANS

Additional data can be harmonised as necessary to meet requirements of new projects. Biological specimens collected during pregnancy and at delivery are potentially available for assay, as are results from assays conducted on these specimens for other projects. The study size allows consideration of CP subtypes, which is rare in aetiological studies of CP. In addition, MOBAND-CP provides a platform within the context of a merged birth cohort of exceptional size that could, after appropriate permissions have been sought, be used for cohort and case-cohort studies of other relatively rare health conditions of infants and children.