Social inequalities in low birth weight in England and Wales: trends and implications for future population health

Socio-economic differences among low-birthweight infants in Hungary. Results of the Cohort '18 -Growing Up in Hungary birth cohort study

BACKGROUND

As Hungary had the fifth-highest rate of low-birthweight (LBW) in the EU27 in 2020, LBW still remains a public health problem for the country.

OBJECTIVE

Our goal is to examine whether LBW in Hungary is determined by the mothers' educational attainment, adjusted for other maternal characteristics (SES, health behaviour and psychological status during pregnancy) among mothers who gave birth in 2018-2019 in Hungary.

METHODS

Source of data is the first and second wave of the Cohort '18 -Growing Up in Hungary longitudinal birth cohort study (n = 8185). It is based on a nationwide representative sample of pregnant women who gave birth between March 2018 and April 2019. All data were self-reported by mothers. We examined the association between maternal educational attainment and the risk of giving birth to an LBW-child (<2500g) by using logistic regression analysis. The highest educational attainment of the mother is measured by a five-value categorical variable (ISCED 97: 0-1; 2; 3C; 3-4; 5-6).

RESULTS

5.9% of women had LBW children. This rate is 18.0% among the lowest educated women with ISCED 97: 0-1; and it is 3.6% among the highest educated women with ISCED 97: 5-6. The adjusted predicted probabilities of LBW for these two groups of women are 13.5%, and 3.4% respectively, adjusted for household income quantiles, Roma ethnic background, residence place, smoking, alcohol consumption, and depression during pregnancy; controlled for mother's height, age at birth, parity and child's sex. Compared to women with the lowest level of education, the risk of giving birth to an LBW child decreases by 34.6% for those with the second level of education, by 60.1% for those with the third level of education, by 72.5% for those with the fourth level of education and by 77.2% for those with the highest level of education. Smoking during pregnancy significantly increases the risk of giving birth to an LBW by 54.9%. Being depressed at 7th month of pregnancy decreased the risk of giving birth to an LBW child in our sample by 13.2%, however the relationship is not significant.

CONCLUSION

Our analysis confirmed that maternal educational attainment has a significant impact on the risk of LBW net of by other maternal SES and health behaviour factors. Nevertheless, even after adjusting for these covariates, inequality in LBW by maternal educational attainment persists.

Socioeconomic risk factors for low birth weight newborns: A population-based study

Low birth weight (LBW) is an important indicator of maternal health and poverty. This study explored the socioeconomic factors associated with LBW.

METHODS

Data was collected from a 4-year maternal-newborn registry.

RESULTS

There were 5,316 LBW and 54,029 normal birth weight (NBW). The prevalence of LBW was 9%. The Native women in the LBW group compared to non-native women were 10.4% (1784/5316) vs. 8.4% (3532/5316) with a P-value of 0.001. There were more illiterate mothers in the LBW compared to the NBW, respectively: 8.1% (1597/19497) vs. 7.5% (1763/23230) with a P-value of 0.001. Working mothers tend to have more LBW infants compared to mothers with NBW, 8.4% (1588/17217) vs. 7.9% (2532/31891) and P-value 0.001. Young mothers (<20 years old) with early childbearing had more LBW compared to older mothers, respectively 12.7% (180/1414) vs. 8.9% (5149/52919) P-value <0.001. Women with no antenatal care reported a high rate of LBW compared to women with regular antenatal care: 14.2% (516/3696) vs. 8.6% (4741/55691) P-value <0.001. LBW babies were born more from assisted conception pregnancies (38% compared to 8.4% of normal pregnancies) P-value <0.001. Smoking mothers scored higher with LBW at 13.6% vs. 8.3% and a P-value of 0.001. There were no differences between the two groups regarding religion, consanguinity, marital status, or family income.

CONCLUSION

Risk factors for low birth weight can be improved by providing antenatal care, smoking cessation, optimizing high-risk pregnancy care, and governing assisted reproduction regulations.

Exploring the socioeconomic disparities of maternal body mass index: a national study in France

BACKGROUND

The prevalence of overweight and obesity has increased in various countries. Normal weight before pregnancy is important to protect maternal and newborn health. This study aimed to describe the evolution of body mass index (BMI) before pregnancy in France and explore its association with two measures of socioeconomic status (SES), education and household income.

METHODS

Data were from four national perinatal surveys in France in 1998, 2003, 2010 and 2016 to describe the time evolution of maternal BMI. We explored the links between BMI and women's characteristics in the most recent period (2010-2016 surveys) since income information was not available before. Risk ratios (RRs) of underweight, overweight and obesity for each measure of SES were computed by using multivariable Poisson regression models.

RESULTS

Overweight and obesity prevalence increased between 1998 and 2016, from 6% to 12% for obesity. Both were inversely associated with SES (higher prevalence among least educated and poorest women), with strong variations for each social indicator, even in multivariable analyses including both. Combining education and income revealed a wide gradient; RR for obesity was 6.01 (95% confidence interval 4.89-7.38) with low education and income <2000 euros/month vs. high education and income ≥4000 euros/month.

CONCLUSIONS

Public policies must implement programs to limit the increase in overweight and its unequal distribution in the population, alongside other policies to address the societal determinants of the obesogenic environment. Health professionals need to advise women to improve their eating and physical activity to limit weight gain from childhood to early adulthood.

Pregnancy loss and Income in the Republic of Korea using National Health Insurance Service Data, 2008-2014

Background

Although unintentional pregnancy loss is common, national representative statistics are lacking in high-income East Asian countries undergoing rapid demographic changes. It is necessary to confirm the income inequality of pregnancy loss even in universal national health insurance.

Method

Using National Health Insurance Service data between 2008 and 2014, the annual prevalence of pregnancy loss was enumerated, and differences in pregnancy loss according to age and income levels were assessed by multivariable Poisson regression. Joint-point regression was used to examine the trend of pregnancy loss.

Result

On average, there was a 15.0% annual pregnancy loss among 3,941,020 pregnancy cases from 2008 to 2014. Pregnancy loss inequality increased stepwise with income levels except for the highest income group. After adjusting for income levels, the annual percent change of age-standardized prevalence significantly increased by 2.6% every year since 2011.

Conclusion

Even in high-income countries with universal national health insurance, income inequality in pregnancy loss is observed. Further appraisal is needed to explain the increasing trend of pregnancy loss between 2011 and 2014 even after adjusting income.

A Systematic Review and Meta-analysis on the Prevalence of Low Birth Weight Infants in Iran

Background

Low birth weight is a significant index for survival, intrauterine growth, and mortality in infants. Thus, this study is aimed at determining the prevalence of low birth weight in Iranian infants through a systematic review and meta-analysis.

Methods

This study was performed by meta-analysis from January 2000 to December 2019. The studies relevant to the topic have been obtained through search in databases of Scopus, ScienceDirect, SID, Magiran, Barakat Knowledge Network System, Medline (PubMed), and Google Scholar. Heterogeneity of the studies has been assessed by the I² index, and data analysis was done using Comprehensive Meta-Analysis software.

Results

By investigating 14 articles and 93924 infants, the total prevalence of low birth weight in infants in Iran was achieved at 8.5% (95% CI: 7.3-9.9%) according to the meta-analysis; the most prevalence of low birth weight was in infants in Hamedan at 19.1% (95% CI: 21.2-17.2%) in 2007, and the lowest prevalence of low birth weight was in infants in Tonekabon at 4.2% (95% CI: 3.4-5.2%) in 2005, and also, by increasing the sample size, the prevalence of low birth weight increases, by which the difference is statistically significant (P < 0.05).

Conclusion

Due to the high prevalence of low birth weight in infants in Iran, health policy-makers must take effective attempts in order to reduce it in infants.

Prevalence of self-reported mental disorders in pregnancy and associations with adverse neonatal outcomes: a population-based cross-sectional study

BACKGROUND

Mental disorders in pregnancy are common causes of morbidity and mortality with associated risks of adverse neonatal outcomes. Our aims were to evaluate the prevalence of self-reported mental disorders in women presenting to maternity services and to determine the association between history of self-reported maternal mental disorder and adverse neonatal outcomes.

METHODS

Data on all singleton pregnancies known to maternity services in Northern Ireland over the period 2010 to 2015 were extracted from the Northern Ireland Maternity System (NIMATS), including frequency data for number of pregnancies where the mother reported a history of mental disorder. Odds ratios were derived from logistic regression analyses to determine the associations between self-reported maternal mental disorder and preterm birth, low infant birth weight and APGAR scores.

RESULTS

In total, 140,569 singleton pregnancies were registered using NIMATS over this period. In 18.9% of these pregnancies, the mother reported a history of at least one mental disorder. After adjustment for potential confounding factors, significant associations were demonstrated between self-reported maternal mental disorder and preterm birth (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.25-1.37), low infant birth weight (OR 1.29, 95% CI 1.21-1.38) and APGAR score < 7 at 1 min (OR 1.14, 95% CI 1.10-1.19) and 5 min (OR 1.23, 95% CI 1.12 to 1.34).

CONCLUSIONS

These findings emphasise the critical importance of routine enquiry regarding psychiatric history when women present to maternity services and the impact of maternal mental illnesses upon outcomes for their infants.

Low Birth Weight and Its Associated Factors among Newborns Delivered at Wolaita Sodo University Teaching and Referral Hospital, Southern Ethiopia, 2018

BACKGROUND

Birth weight has a vital role in determining newborns survival in vulnerable conditions. Low birth weight is associated with fetal and neonatal morbidity and mortality, impairment of growth and development and also chronic disease later in life. This study was aimed to assess the magnitude of low birth weight and its determinants in Wolaita Sodo University teaching and referral hospital, southern Ethiopia.

METHODS

Institution based cross-sectional study was conducted from November to December 2018. Systematic random sampling technique was used to select study participants. Data was collected by interviewing mothers through structured questionnaire and reviewing neonates' medical records using a checklist. Multivariable binary logistic regression analyses were employed to identify factors associated with neonatal jaundice.

RESULTS

The proportion of low birth weight in the study area was found to be 15.8% (95% CI 11.7-19.9). Being primiparity [AOR=5.798; 95% (1.572-21.377)], anemia during pregnancy [AOR=3.808; 95% (1.513-9.586)], pregnancy induced hypertension [AOR= 6.955; 95% (2.386- 20.275)], intake herbal medication during pregnancy [AOR=35.762; 95% (4.571-279.764)], drinking alcohol during pregnancy [AOR=8.111; 95% (2.359-27. 895)] were predictors of low birth weight.

CONCLUSION

The proportion of low birth weight among newborns delivered at Wolaita Sodo University teaching and referral hospital was comparable with the global prevalence of low birth weight. Parity, anemia, alcohol, herbal medication, and pregnancy-induced hypertension were significantly associated with low birth weight.

Birth weight trends in England and Wales (1986-2012): babies are getting heavier

INTRODUCTION

Birth weight is a strong predictor of infant mortality, morbidity and later disease risk. Previous work from the 1980s indicated a shift in the UK towards heavier births; this descriptive analysis looks at more recent trends.

METHODS

Office for National Statistics (ONS) registration data on 17.2 million live, single births from 1986 to 2012 were investigated for temporal trends in mean birth weight, potential years of birth weight change and changes in the proportions of very low (<1500 g), low (<2500 g) and high (≥4000 g) birth weight. Analysis used multiple linear and logistic regression adjusted for maternal age, marital status, area-level deprivation and ethnicity. Additional analyses used the ONS NHS Numbers for Babies data set for 2006-2012, which has information on individual ethnicity and gestational age.

RESULTS

Over 27 years there was an increase in birth weight of 43 g (95% CI 42 to 44) in females and 44 g (95% CI 43 to 45) in males, driven by birth weight increases between 1986-1990 and 2007-2012. There was a concurrent decreased risk of having low birth weight but an 8% increased risk in males and 10% increased risk in females of having high birth weight. For 2006-2012 the birth weight increase was greater in preterm as compared with term births.

CONCLUSIONS

Since 1986 the birth weight distribution of live, single births in England and Wales has shifted towards heavier births, partly explained by increases in maternal age and non-white ethnicity, as well as changes in deprivation levels. Other potential influences include increases in maternal obesity and reductions in smoking prevalence particularly following the introduction of legislation restricting smoking in public places in 2007.

Socioeconomic disadvantage, fetal environment and child development: linked Scottish administrative records based study

Background

Cognitive development in childhood is negatively affected by socioeconomic disadvantage. This study examined whether differences in fetal environment might mediate the association between family socioeconomic position and child development.

Methods

Data were linked from the Scottish Longitudinal Study, maternity inpatient records and the Child Health Surveillance Programme – Pre School for 32,238 children. The outcome variables were based on health visitor assessment of gross motor, hearing and language, vision and fine motor, and social development. Socioeconomic position was measured using parental social class and highest qualification attained. Random-effects logistic regression models were estimated to account for multiple reviews and familial clustering. Mediation analysis was conducted using the Karlson-Holm-Breen method.

Results

Hearing and language, vision and fine motor, and social development were associated with lower parental social class and lower parental educational qualifications after adjustment for fetal environment. Fetal environment partially mediated the estimated effect of having parents without educational qualifications for hearing and language (β = 0·15; 95% confidence interval (CI) = 0·07, 0·23), vision and fine motor (β = 0·19; CI = 0·10, 0·28) and social development (β = 0·14; CI = 0·03 to 0·25).

Conclusions

Socioeconomic position predicted hearing and language, vision and fine motor, and social development but not gross motor development. For children of parents without educational qualifications, fetal environment appears to contribute to a part of the socioeconomic gradient in child development abnormalities but post-natal environment appears to still explain the majority of the gradient and for other children most of it.

Electronic supplementary material

The online version of this article (10.1186/s12939-017-0698-4) contains supplementary material, which is available to authorized users.

Is there evidence that the yearly numbers of children newly certified with sight impairment in England and Wales has increased between 1999/2000 and 2014/2015? A cross-sectional study

OBJECTIVES

To use routine data capture from hospitals in England and Wales to identify whether there has been an increase in the annual numbers of children newly certified sight impaired in England and Wales between 1999/2000 and 2014/2015 and to examine causes of certifiable sight impairment in children certified in 2014/2015.

DESIGN

A cross-sectional study including an analysis of all certificates of vision impairment completed in hospitals in England and Wales each year between 2007/2008 and 2014/2015 and all certificates completed in hospitals in England and Wales in 1999/2000.

PARTICIPANTS

Certificates for all individuals aged 16 years or less at the time of certification in England and Wales for each financial year between 1 April 2007 and the 31 March 2015 and for individuals aged 15 years or less for the year ending 31 March 2000. We obtained information on the main cause of certifiable sight loss for all children certified in 2014/2015. We estimated crude and sex specific incidence estimates with 95% confidence intervals computed by Byars method.

RESULTS

In 1999/2000, the estimated incidence (95 % CI) of certification was 8.2 (7.7 to 8.8) per 1 00 000. In 2007/2008, the estimated incidence was statistically significantly higher at 10.1 (9.5 to 10.7). Since then a trend of increasing incidence with time has been observed until 2014/2015 when an estimated incidence of 13.3 (12.6 to 14.0) was observed. Hereditary retinal dystrophies, cerebral visual impairment and nystagmus were the most common single causes of certifiable sight impairment in children in 2014/2015.

CONCLUSION

Our findings show that in England and Wales there has been an increase in the number of children newly certified sight impaired by consultant ophthalmologists since 1999/2000. This mirrors our previous findings based on data originating within social service departments.

Pregnancy-specific stress, fetoplacental haemodynamics, and neonatal outcomes in women with small for gestational age pregnancies: a secondary analysis of the multicentre Prospective Observational Trial to Optimise Paediatric Health in Intrauterine Growth Restriction

OBJECTIVES

To examine associations between maternal pregnancy-specific stress and umbilical (UA PI) and middle cerebral artery pulsatility indices (MCA PI), cerebroplacental ratio, absent end diastolic flow (AEDF), birthweight, prematurity, neonatal intensive care unit admission and adverse obstetric outcomes in women with small for gestational age pregnancies. It was hypothesised that maternal pregnancy-specific stress would be associated with fetoplacental haemodynamics and neonatal outcomes.

DESIGN

This is a secondary analysis of data collected for a large-scale prospective observational study.

SETTING

This study was conducted in the seven major obstetric hospitals in Ireland and Northern Ireland.

PARTICIPANTS

Participants included 331 women who participated in the Prospective Observational Trial to Optimise Paediatric Health in Intrauterine Growth Restriction. Women with singleton pregnancies between 24 and 36 weeks gestation, estimated fetal weight <10th percentile and no major structural or chromosomal abnormalities were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Serial Doppler ultrasound examinations of the umbilical and middle cerebral arteries between 20 and 42 weeks gestation, Pregnancy Distress Questionnaire (PDQ) scores between 23 and 40 weeks gestation and neonatal outcomes.

RESULTS

Concerns about physical symptoms and body image at 35-40 weeks were associated with lower odds of abnormal UAPI (OR 0.826, 95% CI 0.696 to 0.979, p=0.028). PDQ score (OR 1.073, 95% CI 1.012 to 1.137, p=0.017), concerns about birth and the baby (OR 1.143, 95% CI 1.037 to 1.260, p=0.007) and concerns about physical symptoms and body image (OR 1.283, 95% CI 1.070 to 1.538, p=0.007) at 29-34 weeks were associated with higher odds of abnormal MCA PI. Concerns about birth and the baby at 29-34 weeks (OR 1.202, 95% CI 1.018 to 1.421, p=0.030) were associated with higher odds of AEDF. Concerns about physical symptoms and body image at 35-40 weeks were associated with decreased odds of neonatal intensive care unit admission (OR 0.635, 95% CI 0.435 to 0.927, p=0.019).

CONCLUSIONS

These findings suggest that fetoplacental haemodynamics may be a mechanistic link between maternal prenatal stress and fetal and neonatal well-being, but additional research is required.

Prenatal stress and hemodynamics in pregnancy: a systematic review

Maternal prenatal stress is associated with preterm birth, intrauterine growth restriction, and developmental delay. However, the impact of prenatal stress on hemodynamics during pregnancy remains unclear. This systematic review was conducted in order to assess the quality of the evidence available to date regarding the relationship between prenatal stress and maternal-fetal hemodynamics. The PubMed/Medline, EMBASE, PsycINFO, Maternity and Infant Care, Trip, Cochrane Library, and CINAHL databases were searched using the search terms pregnancy; stress; fetus; blood; Doppler; ultrasound. Studies were eligible for inclusion if prenatal stress was assessed with standardized measures, hemodynamics was measured with Doppler ultrasound, and methods were adequately described. A specifically designed data extraction form was used. The methodological quality of included studies was assessed using well-accepted quality appraisal guidelines. Of 2532 studies reviewed, 12 met the criteria for inclusion. Six reported that prenatal stress significantly affects maternal or fetal hemodynamics; six found no significant association between maternal stress and circulation. Significant relationships between prenatal stress and uterine artery resistance (RI) and pulsatility (PI) indices, umbilical artery RI, PI, and systolic/diastolic ratio, fetal middle cerebral artery PI, cerebroplacental ratio, and umbilical vein volume blood flow were found. To date, there is limited evidence that prenatal stress is associated with changes in circulation. More carefully designed studies with larger sample sizes, repeated assessments across gestation, tighter control for confounding factors, and measures of pregnancy-specific stress will clarify this relationship.

Routinely collected English birth data sets: comparisons and recommendations for reproductive epidemiology

BACKGROUND

In England there are four national routinely collected data sets on births: Office for National Statistics (ONS) births based on birth registrations; Hospital Episode Statistics (HES) deliveries (mothers' information); HES births (babies' information); and NHS Numbers for Babies (NN4B) based on ONS births plus gestational age and ethnicity information. This study describes and compares these data, with the aim of recommending the most appropriate data set(s) for use in epidemiological research and surveillance.

METHODS

We assessed the completeness and quality of the data sets in relation to use in epidemiological research and surveillance and produced detailed descriptive statistics on common reproductive outcomes for each data set including temporal and spatial trends.

RESULTS

ONS births is a high quality complete data set but lacks interpretive and clinical information. HES deliveries showed good agreement with ONS births but HES births showed larger amounts of missing or unavailable data. Both HES data sets had improved quality from 2003 onwards, but showed some local spatial variability. NN4B showed excellent agreement with ONS and HES deliveries for the years available (2006-2010). Annual number of births increased by 17.6% comparing 2002 with 2010 (ONS births). Approximately 6% of births were of low birth weight (2.6% term low birth weight) and 0.5% were stillbirths.

CONCLUSIONS

Routinely collected data on births provide a valuable resource for researchers. ONS and NN4B offer the most complete and accurate record of births. Where more detailed clinical information is required, HES deliveries offers a high quality data set that captures the majority of English births.

Birthweight Related Factors in Northwestern Iran: Using Quantile Regression Method

INTRODUCTION

Birthweight is one of the most important predicting indicators of the health status in adulthood. Having a balanced birthweight is one of the priorities of the health system in most of the industrial and developed countries. This indicator is used to assess the growth and health status of the infants. The aim of this study was to assess the birthweight of the neonates by using quantile regression in Zanjan province.

METHODS

This analytical descriptive study was carried out using pre-registered (March 2010 - March 2012) data of neonates in urban/rural health centers of Zanjan province using multiple-stage cluster sampling. Data were analyzed using multiple linear regressions andquantile regression method and SAS 9.2 statistical software.

RESULTS

From 8456 newborn baby, 4146 (49%) were female. The mean age of the mothers was 27.1±5.4 years. The mean birthweight of the neonates was 3104 ± 431 grams. Five hundred and seventy-three patients (6.8%) of the neonates were less than 2500 grams. In all quantiles, gestational age of neonates (p<0.05), weight and educational level of the mothers (p<0.05) showed a linear significant relationship with the i of the neonates. However, sex and birth rank of the neonates, mothers age, place of residence (urban/rural) and career were not significant in all quantiles (p>0.05).

CONCLUSION

This study revealed the results of multiple linear regression and quantile regression were not identical. We strictly recommend the use of quantile regression when an asymmetric response variable or data with outliers is available.

Childbirth expense support and small-for-gestational-age infants in Japan

BACKGROUND

Poor nutritional status during the fetal period could cause perinatal and lifelong health disadvantages in neonates. The aim of this study was to investigate the background of pregnant women receiving childbirth expense support (CES), pregnancy outcome, and neonatal anthropometric data.

METHODS

A retrospective cohort study was conducted using 823 antenatal and delivery records in a perinatal center located in one of the poorest areas in Japan. Neonates who were small for gestational age (SGA) were compared between the CES and the non-CES groups.

RESULTS

The incidences of low birthweight (LBW) and SGA were significantly higher in the group receiving CES (14.6% and 14.6%, respectively). The adjusted OR of CES was 2.78 (95%CI: 1.32-5.87) and the adjusted OR of maternal smoking was 5.03 (95%CI: 2.74-9.21), indicating that CES and maternal smoking were directly associated with SGA.

CONCLUSIONS

CES recipients had a higher prevalence of SGA infants. CES was independently associated with SGA. Previous studies have shown that smoking is a major risk factor for SGA. Further studies are needed to identify risk factors of SGA specific to CES recipients.

Place of work and residential exposure to ambient air pollution and birth outcomes in Scotland, using geographically fine pollution climate mapping estimates

OBJECTIVES

A relationship between ambient air pollution and adverse birth outcomes has been found in a large number of studies that have mainly used a nearest monitor methodology. Recent research has suggested that the effect size may have been underestimated in these studies. This paper examines associations between birth outcomes and ambient levels of residential and workplace sulphur dioxide, particulates and Nitrogen Dioxide estimated using an alternative method - pollution climate mapping.

METHODS

Risk of low birthweight and mean birthweight (for n=21,843 term births) and risk of preterm birth (for n=23,086 births) were modelled against small area annual mean ambient air pollution concentrations at work and residence location adjusting for potential confounding factors for singleton live births (1994-2008) across Scotland.

RESULTS

Odds ratios of low birthweight of 1.02 (95% CI, 1.01-1.03) and 1.07 (95% CI, 1.01-1.12) with concentration increases of 1 µg/m(3) for NO2 and PM10 respectively. Raised but insignificant risks of very preterm birth were found with PM10 (relative risk ratio=1.08; 95% CI, 1.00 to 1.17 per 1 µg/m(3)) and NO2 (relative risk ratio=1.01; 95% CI, 1.00 to 1.03 per 1 µg/m(3)). An inverse association between mean birthweight and mean annual NO2(-1.24 g; 95% CI, -2.02 to -0.46 per 1 µg/m(3)) and PM10 (-5.67 g; 95% CI, -9.47 to -1.87 per 1 µg/m(3)). SO2 showed no significant associations.

CONCLUSIONS

This study highlights the association between air pollution exposure and reduced newborn size at birth. Together with other recent work it also suggests that exposure estimation based on the nearest monitor method may have led to an under-estimation of the effect size of pollutants on birth outcomes.

Perfluoroalkyl and polyfluoroalkyl substances and human fetal growth: a systematic review

BACKGROUND

Exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is ubiquitous in most regions of the world. The most commonly studied PFASs are perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). Animal studies indicate that maternal PFAS exposure is associated with reduced fetal growth. However, the results of human studies are inconsistent.

OBJECTIVES

To summarize the evidence of an association between exposure to PFASs, particularly PFOS and PFOA, and human fetal growth.

METHODS

Systematic literature searches were performed in MEDLINE and EMBASE. We included original studies on pregnant women with measurements of PFOA or PFOS in maternal blood during pregnancy or the umbilical cord and associations with birth weight or related outcomes according to the PFAS level. Citations and references from the included articles were investigated to locate more relevant articles. Study characteristics and results were extracted to structured tables. The completeness of reporting as well as the risk of bias and confounding were assessed.

RESULTS

Fourteen studies were eligible. In utero PFOA exposure was associated with decreased measures of continuous birth weight in all studies, even though the magnitude of the association differed and many results were statistically insignificant. PFOS exposure and birth weight were associated in some studies, while others found no association.

CONCLUSIONS

Higher PFOS and PFOA concentrations were associated with decreased average birth weight in most studies, but only some results were statistically significant. The impact on public health is unclear, but the global exposure to PFASs warrants further investigation.

TESTING THE EFFECT OF THE EPIDEMIOLOGIC PARADOX: BIRTH WEIGHT OF NEWBORNS OF IMMIGRANT AND NON-IMMIGRANT MOTHERS IN THE REGION OF VALENCIA, SPAIN

The epidemiological paradox and ‘healthy migrant effect’ refer to the favourable health outcomes in unprivileged groups under unfavourable socioeconomic conditions. Weight at birth is associated with the epidemiological paradox. However, differences in fertility structure (mainly mother's age and first maternity) might be the cause of the difference in weight at birth between children of immigrant and non-immigrant mothers. This paper aims to analyse the impact of the epidemiologic paradox by distinguishing between the factors related to fertility structure, in addition to other socio-cultural factors. The importance of fertility structure as the cause of weight-at-birth differences of the newborns of immigrant and non-immigrant women, and between those of subgroups of immigrant mothers, is tested. Based on data from birth registries for the period 1998–2009, a variance analysis was performed for Spanish mothers and for those of five major immigrant subgroups living in the region of Valencia, Spain, which experienced significant migrant inflows within a short period of time. A Scheffé test between pairs of nationalities was carried out. Finally, linear regression models were built. The results suggest that the most relevant factors are those related to fertility structure, and that consequently the epidemiological paradox does not apply for immigrant mothers as a whole, although Bolivian immigrant offspring may be an exception. This unexpected result requires further research to test to what extent this is due to the special adaptation of multigenerational high-altitude populations in pregnancy. The factors associated with fertility structure must be controlled when trying to relate birth weight differences between ethnic groups to socioeconomic factors.

The relationship between biological cognitive and psychosocial characteristics of parents and the weight of infant at the time of birth in Isfahan

INTRODUCTION

The present study was connected in order to evaluate the relationship between biological, cognitive and psychosocial characteristics of mothers and the weight of infant at the time of birth.

MATERIALS AND METHODS

In order to conduct this research a sample of 910 women among recently delivered mothers of Isfahan province in 2009 were selected. From stratified sampling and cluster sampling according to the percentage of population in each of the cities of Isfahan Province was used. The data was gathered with a questionnaire prepared by the researcher in order to evaluate the biological cognitive and psychosocial characteristics of mothers, in addition to the Enrich marital satisfaction test. After collecting data, the analysis of the data was done with SPSS software in two categories of descriptive and inferential statistics by using logistic regression model.

RESULTS

The results showed that the prevalence of low weight infants was 9.5 percent and 38.7 percent of pregnancies was unwanted. Twenty-nine percent of mothers had marital dissatisfaction. 15/6 percent of pregnancies were below 20 years old and 22 percent was above of 35 years old. 38.9 percent of mothers were exposed to cigarette smoke. The average of weight gain during pregnancies was 9 kilograms. Thirty three percent of mothers had high blood pressure during pregnancy, 26.7 percent had history of abortion and 31.9 percent had history of bleeding. 23/1percent of women was employed during pregnancy, 19.8 percent gave twin birth and 21/1 percent of parents were relative of each other, 29.7 percent of deliveries were done in cesarean way.

CONCLUSION

The results of this study showed that severe marital dissatisfaction, abnormal blood pressure during pregnancy, being employed during pregnancy, weight gain less than 5 Kg during pregnancy, pregnancy below the age of 20 can meaning fully increase the possibility of low birth weight in infant (α=0.05). The results were consisting with the previous findings and indicated that some of the applicable benefits of this research can be recording of information about each delivery in the whole country with holding training workshops of before and during pregnancy skills by welfare organization.

The social determinants of infant mortality and birth outcomes in Western developed nations: a cross-country systematic review

Infant mortality (IM) and birth outcomes, key population health indicators, have lifelong implications for individuals, and are unequally distributed globally. Even among western industrialized nations, striking cross-country and within-country patterns are evident. We sought to better understand these variations across and within the United States of America (USA) and Western Europe (WE), by conceptualizing a social determinants of IM/birth outcomes framework, and systematically reviewing the empirical literature on hypothesized social determinants (e.g., social policies, neighbourhood deprivation, individual socioeconomic status (SES)) and intermediary determinants (e.g., health behaviours). To date, the evidence suggests that income inequality and social policies (e.g., maternal leave policies) may help to explain cross-country variations in IM/birth outcomes. Within countries, the evidence also supports neighbourhood SES (USA, WE) and income inequality (USA) as social determinants. By contrast, within-country social cohesion/social capital has been underexplored. At the individual level, mixed associations have been found between individual SES, race/ethnicity, and selected intermediary factors (e.g., psychosocial factors) with IM/birth outcomes. Meanwhile, this review identifies several methodological gaps, including the underuse of prospective designs and the presence of residual confounding in a number of studies. Ultimately, addressing such gaps including through novel approaches to strengthen causal inference and implementing both health and non-health policies may reduce inequities in IM/birth outcomes across the western developed world.

The effect of the season of birth and of selected maternal factors on linear enamel thickness in modern human deciduous incisors

OBJECTIVE

Development of human tooth enamel is a part of a foetus's development; its correctness is the outcome of genetic and maternal factors shaping its prenatal environment. Many authors reported that individuals born in different seasons experience different early developmental conditions during pregnancy. In this study, we investigated the effects of season of birth and selected maternal factors on enamel thickness of deciduous incisors.

DESIGN

Dental sample comprises 60 deciduous incisors. The parents who handed over their children's teeth for research fill in questionnaires containing questions about the course of pregnancy. All teeth were sectioned in the labio-linqual plane using diamond blade (Buechler IsoMet 1000). The final specimens were observed by way of scanning electron microscopy at magnifications 80× and 320×. The thickness of total enamel (TE), prenatally (PE) and postnatally (PSE) formed enamel was measured.

RESULTS

Children born in summer and in spring (whose first and second foetal life fall on autumn and winter) have the thinnest enamel. Season of birth, number of children in family, diseases and spasmolytic medicines using by mother during pregnancy explained almost 13% of the variability of TE. Regression analysis proved a significant influence of the season of birth and selected maternal factors on the PE thickness - these factors explained over 17% of its variability. Neither of analysed variables had influenced PSE.

CONCLUSIONS

Our findings suggests that the thickness of enamel of deciduous incisors depends on the season of birth and some maternal factors. The differences were observed only in the prenatally formed enamel.

Pregnancy: occupational aspects of management: concise guidance

Most pregnant women are exposed to some physical activity at work. This Concise Guidance is aimed at doctors advising healthy women with uncomplicated singleton pregnancies about the risks arising from five common workplace exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload). The adverse outcomes considered are: miscarriage, preterm delivery, small for gestational age, low birth weight, pre-eclampsia and gestational hypertension. Systematic review of the literature indicates that these exposures are unlikely to carry much of an increased risk for any of the outcomes, since small apparent effects might be explicable in terms of chance, bias, or confounding, while larger and better studies yield lower estimated risks compared with smaller and weaker studies. In general, patients can be reassured that such work is associated with little, if any, adverse effect on pregnancy. Moreover, moderate physical exercise is thought to be healthy in pregnancy and most pregnant women undertake some physical work at home. The guidelines provide risk estimates and advice on counselling.

Mediating role of education and lifestyles in the relationship between early-life conditions and health: evidence from the 1958 British cohort

The paper focuses on the long-term effects of early-life conditions with comparison to lifestyles and educational attainment on health status in a cohort of British people born in 1958. Using the longitudinal follow-up data at age 23, 33, 42 and 46, we build a dynamic model to investigate the influence of each determinant on health and the mediating role of education and lifestyles in the relationship between early-life conditions and later health. Direct and indirect effects of early-life conditions on adult health are explored using auxiliary linear regressions of education and lifestyles and panel Probit specifications of self-assessed health with random effects addressing individual unexplained heterogeneity. Our study shows that early-life conditions are important parameters for adult health accounting for almost 20% of explained health inequality when mediating effects are identified. The contribution of lifestyles reduces from 32% down to 25% when indirect effects of early-life conditions and education are distinguished. Noticeably, the absence of father at the time of birth and experience of financial hardships represent the lead factors for direct effects on health. The absence of obesity at 16 influences health both directly and indirectly working through lifestyles.

Prenatal Health, Educational Attainment, and Intergenerational Inequality: The Northern Finland Birth Cohort 1966 Study

In this article, we study the effects of prenatal health on educational attainment and on the reproduction of family background inequalities in education. Using Finnish birth cohort data, we analyze several maternal and fetal health variables, many of which have not been featured in the literature on long-term socioeconomic effects of health despite the effects of these variables on birth and short-term health outcomes. We find strong negative effects of mother’s prenatal smoking on educational attainment, which are stronger if the mother smoked heavily but are not significant if she quit during the first trimester. Anemia during pregnancy is also associated with lower levels of attained education. Other indicators of prenatal health (pre-pregnancy obesity, mother’s antenatal depressed mood, hypertension and preeclampsia, early prenatal care visits, premature birth, and small size for gestational age) do not predict educational attainment. Our measures explain little of the educational inequalities by parents’ class or education. However, smoking explains 12%—and all health variables together, 19%—of the lower educational attainment of children born to unmarried mothers. Our findings point to the usefulness of proximate health measures in addition to general ones. They also point to the potentially important role played by early health in intergenerational processes.

Risk factors for low birth weight in Botucatu city, SP state, Brazil: a study conducted in the public health system from 2004 to 2008

BACKGROUND

Low birth weight (LBW), defined as birth weight less than 2500 g, has a complex etiology and may be a result of premature interruption of pregnancy or intrauterine growth restriction. The objective of this study was to provide information on determinants of LBW and contribute to the understanding of the problem in Brazil.

METHODS

A case-control study was conducted in Botucatu city, SP state, Brazil. The study population consisted of 2 groups with 860 newborns in each group as follows: low weight newborns (LWNB) and a control group (weight ≥ 2500 g). Secondary data from 2004 to 2008 were collected using the Live Birth Certificate (LBC) and records from medical charts of pregnant women in Basic Health Units (BHU) and in the Public University Hospital (UH). Variables were as follows: maternal socio-demographic characteristics, pregnancy and birth conditions including quality of prenatal care according to 3 criteria. They were based on parameters established by the Ministry of Health (MH), one of them, the modified Kessner Index. The multivariable analysis by logistic regression was used to evaluate the association between variables and LBW.

RESULTS

According to the analysis, the factors associated with LBW were as follows: prematurity (OR = 56.98, 95% CI 29.52-109.95), twin pregnancy (OR = 20.00, 95% CI 6.25-100.00), maternal smoking (OR = 2.12, 95% CI 1.33-3.45), maternal malnourishment (OR = 2.30, 95% CI 1.08-5.00), maternal obesity (OR = 2.30, 95% IC 1.18-4.48), weight gain during pregnancy less than 5 kg (OR = 2.63, 95% CI 1.35-5.00) and weight gain during pregnancy more than 15 kg (OR = 2.26, 95% CI 1.16-4.41). Adequacy of prenatal care visits adjusted to gestational age was less frequent in the LBW group than in the control group (68.7% vs. 80.5%, x2 p < 0.001). According to the modified Kessner Index, 64.4% of prenatal visits in the LWNB group were adequate.

CONCLUSION

LWNB are a quite heterogeneous group of infants concerning their determinants and prevention actions against LBW and the follow-up of these infants have also been very complex. Therefore, improvement in the quality of care provided should be given priority through concrete actions for prevention of LBW.

Intergenerational correlations in size at birth and the contribution of environmental factors: The Uppsala Birth Cohort Multigenerational Study, Sweden, 1915-2002

Sizes at birth of parents and their children are known to be correlated, reflecting in part the influence of fetal and maternal genes. Sociodemographic factors, regarded as aspects of the shared environment across generations, would also be expected to contribute, but evidence is limited. In the present study, the authors aimed to quantify the role of the shared environment in explaining intergenerational correlations in birth weight and length by using data across 3 consecutive generations from the Uppsala Birth Cohort Multigenerational Study in Uppsala, Sweden. That study included birth and sociodemographic data on 7,657 singletons born in Uppsala in 1915-1929 (generation 1) and their grandchildren (generation 3). Standard regression and biometric models were used to study the correlations in size at birth of generation 1-generation 3 pairs. The data showed stronger correlations in maternal pairs than in paternal pairs for birth weight (0.125 vs. 0.096, P = 0.02) but not for birth length (0.097 vs. 0.093, P = 0.77). These correlations were not reduced by adjustment for sociodemographic factors in regression models. In contrast, significant shared-environment contributions to the intergenerational correlations were identified in biometric models, averaging 14% for both birth measures. These models assumed a common latent factor for the sociodemographic variables. The present results show that the shared environment moderately but significantly contributes to intergenerational correlations.

Stressful life events, social health issues and low birthweight in an Australian population-based birth cohort: challenges and opportunities in antenatal care

BACKGROUND

Investment in strategies to promote 'a healthy start to life' has been identified as having the greatest potential to reduce health inequalities across the life course. The aim of this study was to examine social determinants of low birthweight in an Australian population-based birth cohort and consider implications for health policy and health care systems.

METHODS

Population-based survey distributed by hospitals and home birth practitioners to >8000 women six months after childbirth in two states of Australia. Participants were women who gave birth to a liveborn infant in Victoria and South Australia in September/October 2007. Main outcome measures included stressful life events and social health issues, perceived discrimination in health care settings, infant birthweight.

RESULTS

4,366/8468 (52%) of eligible women returned completed surveys. Two-thirds (2912/4352) reported one or more stressful life events or social health issues during pregnancy. Women reporting three or more social health issues (18%, 768/4352) were significantly more likely to have a low birthweight infant (< 2500 grams) after controlling for smoking and other socio-demographic covariates (Adj OR = 1.77, 95% CI 1.1-2.8). Mothers born overseas in non-English speaking countries also had a higher risk of having a low birthweight infant (Adj OR = 1.85, 95% CI 1.2-2.9). Women reporting three or more stressful life events/social health issues were more likely to attend antenatal care later in pregnancy (OR = 2.06, 95% CI 1.3-3.1), to have fewer antenatal visits (OR = 2.17, 95% CI 1.4-3.4) and to experience discrimination in health care settings (OR = 2.69, 95% CI 2.2-3.3).

CONCLUSIONS

There is a window of opportunity in antenatal care to implement targeted preventive interventions addressing potentially modifiable risk factors for poor maternal and infant outcomes. Developing the evidence base and infrastructure necessary in order for antenatal services to respond effectively to the social circumstances of women's lives is long overdue.

Socio-economic and medical determinants of low birth weight in Iran: 20 years after establishment of a primary healthcare network

OBJECTIVE

Establishment of a primary healthcare network in Iran has provided free and universal access to primary health care. Although the health status of Iranians has improved since this network was established, the low-birthweight rate has not decreased. The objective of the present study was to describe socio-economic and medical factors related to low birth weight in the context of free and universal access to primary health care.

DESIGN

Descriptive, hospital-based prospective study.

METHODS

Data about socio-economic, reproductive and prenatal condition of 4510 live singleton births from June to October 2004 were gathered using a standard questionnaire by interview and record review. The effect of these conditions on birth weight was investigated using a logistic regression model.

RESULTS

Of 4510 newborns, 305 (6.8%) were low birth weight. Among these low-birthweight newborns, there were 159 preterm and 146 term newborns. Mothers with a primary and secondary education [odds ratio (OR) 6.83, 95% confidence interval (CI) 2.35-7.34 and OR 4.81, 95%CI 1.95-6.37, respectively], who lived with farmer and unskilled worker husbands (OR 2.52, 95%CI 1.12-4.66 and OR 2.91, 95%CI 1.35-2.52, respectively), with a birth interval of 1 year or less (OR 3.54, 95%CI 1.80-5.95) and height less than 155cm (OR 1.82, 95%CI 1.12-3.31) were more likely to have low-birthweight infants.

CONCLUSION

In the context of free and universal access to health care, it is recommended that policy makers should place more emphasis on education as it imparts knowledge and thus influences dietary habits and birth-spacing behaviour. This will lead to a better nutritional status, particularly in dealing with pregnancy, resulting in lower rates of low birth weight.

Occupational physical activities, working hours and outcome of pregnancy: findings from the Southampton Women's Survey

OBJECTIVES

To investigate risks of physical activity at work by pregnancy trimester, including the effects on head and abdominal circumference.

METHOD

At 34 weeks of gestation we interviewed 1327 mothers from the prospective Southampton Women's Survey (SWS); we asked about their activities (working hours, standing/walking, kneeling/squatting, trunk bending, lifting and night shifts) in jobs held at each of 11, 19 and 34 weeks of gestation, and subsequently ascertained four birth outcomes (preterm delivery, small for gestational age (SGA) and reduced head or abdominal circumference) blinded to employment history.

RESULTS

Risk of preterm delivery was elevated nearly threefold in women whose work at 34 weeks entailed trunk bending for >1 h/day. Small head circumference was more common in babies born to women who worked for >40 h/week. However, no statistically significant associations were found with SGA or small abdominal circumference, and preterm delivery showed little association with long working hours, lifting, standing or shift work.

CONCLUSIONS

There is a need for more research on trunk bending late in pregnancy, and on the relationship of work to reduced head circumference. Our findings on several other occupational exposures common among pregnant workers are reassuring.

Diet and deprivation in pregnancy

Deprivation is associated with poor pregnancy outcome but the role of nutrition as a mediating factor is not well understood. We carried out a prospective cohort study of 1461 singleton pregnancies in Aberdeen, UK during 2000-6. We measured nutrient intake and supplement use, B vitamin and homocysteine status, birth weight, gestational age, neonatal treatment and socio-economic deprivation status. Women in the most deprived deciles were approximately 6 years younger and half as likely to take folic acid supplements periconceptually as the least deprived mothers. Deprivation was associated with low blood folate, high homocysteine and diets low in protein, fibre and many of the vitamins and minerals. The diets of the more deprived women were also characterised by low intakes of fruit, vegetables and oily fish and higher intakes of processed meat, fried potatoes, crisps and snacks. Deprivation was related to preterm birth (OR 1.14 (95 % CI 1.03, 1.25); P = 0.009) and whether the baby required neonatal treatment (OR 1.07 (95 % CI 1.01, 1.14); P = 0.028). Low birth weight was more common in women consuming diets low in vitamin C (OR 0.79 (95 % CI 0.64, 0.97); P = 0.028), riboflavin (OR 0.77 (95 % CI 0.63, 0.93); P = 0.008), pantothenic acid (OR 0.79 (95 % CI 0.65, 0.97); P = 0.023) and sugars (OR 0.78 (95 % CI 0.64, 0.96); P = 0.017) even after adjustment for deprivation index, smoking, marital status and parity. Deprivation in pregnancy is associated with diets poor in specific nutrients and poor diet appears to contribute to inequalities in pregnancy outcome. Improving the nutrient intake of disadvantaged women of childbearing age may potentially improve pregnancy outcome.

Explaining educational inequalities in birthweight: the Generation R Study

Although low socio-economic status has consistently been associated with lower birthweight, little is known about the factors whereby socio-economic disadvantage influences birthweight. We therefore examined explanatory mechanisms that may underlie the association between the educational level of pregnant women, as an indicator of socio-economic status, and birthweight. The study was embedded within a population-based cohort study in the Netherlands. Information on maternal education, offspring's birthweight and several determinants of birthweight was available for 3546 pregnant women of Dutch origin. Infants of the lowest educated women had a statistically significantly lower birthweight than infants of the highest educated women [difference adjusted for gender and gestational age: -123 g (95% CI -167, -79)]. Parity, age of the pregnant women, hypertension, parental height and parental birthweight, marital status, pregnancy planning, financial concerns, number of people in household, weight gain and smoking habits individually explained part of the differences in birthweight, while adjustment for working hours and body mass index resulted in increases in birthweight differences between the educational levels. After full adjustment, the difference in birthweight between lowest and highest education was reduced by 66%. Our study confirmed remarkable educational inequalities in birthweight, a large part of which was explained by pregnancy characteristics, anthropometrics, the psychosocial and material situation, and lifestyle-related factors. Altering smoking habits may be an option to reduce educational differences in birthweight, as many lower-educated women tend to continue smoking during pregnancy. In order to tackle inequalities in birthweight, it is important that interventions are accessible for pregnant women in lower socio-economic strata.

Infants admitted to neonatal units--interventions to improve breastfeeding outcomes: a systematic review 1990-2007

This review aimed to identify interventions to promote breastfeeding or breast milk feeding for infants admitted to the neonatal unit. The medical electronic databases were searched for papers listed between 1990 and June 2005 which had breastfeeding or breast milk as an outcome and which targeted infants who had been admitted to a neonatal unit, thus including the infant and/or their parents and/or neonatal unit staff. Only papers culturally relevant to the UK were included resulting in studies from the USA, Canada, Europe, Australia and New Zealand. This search was updated in December 2007 to include publications up to this date. We assessed 86 papers in full, of which 27 ultimately fulfilled the inclusion criteria. The studies employed a range of methods and targeted different aspects of breastfeeding in the neonatal unit. Variations in study type and outcomes meant that there was no clear message of what works best but skin-to-skin contact and additional postnatal support seemed to offer greater advantage for the infant in terms of breastfeeding outcome. Galactogogues for mothers who are unable to meet their infants' needs may also help to increase milk supply. Evidence of an effect from other practices, such as cup-feeding on breastfeeding was limited; mainly because of a lack of research but also because few studies followed up the population beyond discharge from the unit. Further research is required to explore the barriers to breastfeeding in this vulnerable population and to identify appropriate interventions to improve breastfeeding outcomes.

Socio-economic inequalities in low-birth weight, full-term babies from singleton pregnancies in Taiwan

OBJECTIVES

This study investigated the chronological trend of low-birth weight in full-term babies (TLBW) in Taiwan in the 1980s and 1990s when the nation experienced a rapid economic advancement, and assessed the association between TLBW and parental education and marital status.

DESIGN

Data from liveborn singletons from Taiwan's birth registry, born between 1978 and 1997, were used to calculate overall and socio-economic factor-specific rates of TLBW for every 2-year interval in this 20-year period.

METHODS

Logistic regression models were used to assess the trend of TLBW rates, and the interaction between secular time, selected demographic factors and other predictors.

RESULTS

Among 6,159,070 full-term, liveborn singletons, 208,729 were TLBW. The average annual rate of TLBW was 3.39% in the study period. The period-specific TLBW declined monotonically from 4.41% in 1978-1979 to 2.49% in 1996-1997, representing a 43% deduction. Multiple logistic regression demonstrated persistent declining trends irrespective of the educational level or marital status of the parents. However, the decline was slower for populations of lower socio-economic status, such as less-educated parents and unmarried mothers, which enhanced the inequalities of TLBW risk across populations. The TLBW risk ratios of the least-educated mothers to the most-educated mothers increased from 1.43 in 1978-1979 to 2.05 in 1996-1997. Unmarried status was an independent predictor of elevated risk of TLBW.

CONCLUSIONS

The association between socio-economic inequality and the risk of TLBW infants was sustained over the 1980s and 1990s in Taiwan. Interventions are necessary to promote antenatal care and educational attainment, particularly for lower socio-economic and socially deprived populations in Taiwan.

Area deprivation, individual factors and low birth weight in England: is there evidence of an "area effect"?

OBJECTIVE

To explore the relationship between low and very low birth weights, mother's age, individual socioeconomic status and area deprivation.

DESIGN

Analysis of the incidence of low and very low birth weights by area deprivation, maternal age, social class of household and estimated income.

SETTING

England 1996-2000.

SUBJECTS

2 894 440 singleton live births and the 10% sample of these births for which parents' individual-level socioeconomic measures were coded.

RESULTS

Social class, estimated household income, lone-parenthood and mother's age were all associated with the risk of low and very low birth weight. Even when controlling for these individual level factors, area income deprivation was significantly associated with low and very low birth weight (p<0.00). For low birth weight there was a significant interaction between area income deprivation and mother's age. For very young mothers, the area effect was non-significant (p<0.37). For older mothers, particularly those aged 30-34 years, it was stronger (p<0.00). As a result, mothers aged <18 years, although at relatively high risk of low birth weight irrespective of area income deprivation, were actually at slightly lower risk than mothers aged >40 years in the most deprived areas.

CONCLUSIONS

For all but very young mothers, there seems to be a negative effect on birth weight from living in areas of income deprivation, whatever their individual circumstances.

Association of education and the occurrence of low birthweight in rural southern China during the early and late 1990s

OBJECTIVES

We examined whether education-related inequalities were associated with the occurrence of low birthweight in 6 counties in southern China in the early and late 1990s.

METHODS

The study population consisted of 111,181 women (65,669 in the early 1990s and 45,482 in the late 1990s) in a population-based Perinatal Health Care Surveillance System. We used the chi(2) test, logistic regression, and concentration index for our analyses.

RESULTS

From the early to late 1990s, the mean maternal education level increased significantly, and the percentage of low-birthweight births declined among all groups, for both male and female births, and at all levels of the mother's education. Relative to those with less than 9 years of formal education, there was a decreasing risk of low birthweight among those with 9 to 11 years of formal education (range in adjusted odds ratio=0.69-0.82) and with 12 or more years of formal education (range in adjusted odds ratio=0.51-0.74). Between the early and late 1990s, the concentration index changed from -0.0778 to -0.0656 for male births and from -0.0717 to -0.0813 for female births.

CONCLUSIONS

Education-related inequalities associated with low birthweight persisted from the early to the late 1990s in surveyed areas.

Social inequality and perinatal health: comparison of three Brazilian cohorts

The objective of the present study was to estimate and compare social inequality in terms of three indicators, i.e., low birth weight (LBW), preterm birth (PTB) and small for gestational age (SGA) birth, in three birth cohorts. Two cohorts were from the city of Ribeirão Preto, where data were collected for all 6748 live born singletons in 1978/79 and for one third of live born singletons (2846) in 1994. The third cohort consisted of 2443 singletons born in São Luís over a period of one year (1997/98). In Ribeirão Preto, LBW and PTB rates increased in all social strata from 1978/79 to 1994. Social inequalities regarding LBW and PTB disappeared since the increase in these rates was more accelerated in the groups with higher educational level. The percentage of SGA infants increased over the study period. Social inequality regarding SGA birth increased due to a more intense increase in SGA births in the strata with lower schooling. In São Luís, in 1997/98 there was no social inequality in LBW or PTB rates, whereas SGA birth rate was higher in mothers with less schooling. We speculate that the more accelerated increase in medical intervention, especially due to the increase in cesarean sections in the more privileged groups, could be the main factor explaining the unexpected increase in LBW and PTB rates in Ribeirão Preto and the decrease or disappearance of social inequality regarding these perinatal indicators in the two cities.

Influence of maternal and social factors as predictors of low birth weight in Italy

Background

The purpose of this study is to provide insight into the determinants of low birth weight (LBW) in Italy.

Methods

The study was carried out in a non-teaching hospital in Catanzaro (Italy). All LBW and very LBW newborns (200) were included in the study and a random sample of 400 newborns weighing ≥ 2500 g was selected. Data were collected from the delivery certificates during one year. Smoking activity of mother and familiar and/or social support during pregnancy was gathered through telephone interviews.

Results

Overall annual LBW rate was 11.8%. Among LBW newborn there were 125 preterm and 75 term. Younger mothers, those who smoked during pregnancy, and had fewer prenatal care visits were more likely to deliver a LBW child; moreover, preterm newborns, delivered by caesarean section, and twin or multiple birth were significantly more likely to have a LBW. The comparison of very LBW (<1500 g) to LBW newborns showed that a very LBW was significantly more likely in newborns delivered by less educated mothers, those who work outside the home, live in smaller towns, and had less echographies; moreover, as expected, very LBW newborns were more likely to be preterm.

Conclusion

Several modifiable factors affect the risk of LBW, even when universal access to health care is freely available, but socio-economic status appears to correlate only to very LBW.

Risk of prematurity, low birthweight and pre-eclampsia in relation to working hours and physical activities: a systematic review

BACKGROUND

Occupational activities are suspected of having an adverse impact on outcomes of pregnancy.

AIM

To assess the evidence relating three major adverse outcomes (preterm delivery, low birthweight (LBW) and pre-eclampsia/gestational hypertension) to five common occupational exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload).

METHODS

A systematic search of Medline and Embase (1966-December 2005) using combinations of keywords and medical subject heading terms was conducted. For each relevant paper, standard details were abstracted that were then used to summarise the design features of studies, to rate their methodological quality (completeness of reporting and potential for important bias or confounding) and to provide estimates of effect. For studies with similar definitions of exposure and outcome, pooled estimates of relative risk (RR) in meta-analysis were calculated.

RESULTS

53 reports were identified-35 on preterm delivery, 34 on birth weight and 9 on pre-eclampsia or gestational hypertension. These included 21 cohort investigations. For pre-term delivery, extensive evidence relating to each of the exposures of interest was found. Findings were generally consistent and tended to rule out a more than moderate effect size (RR >1.4). The larger and most complete studies were less positive, and pooled estimates of risk pointed to only modest or null effects. For small-for-gestational age, the position was similar, but the evidence base was more limited. For pre-eclampsia and gestational hypertension, it was too small to allow firm conclusions.

CONCLUSIONS

The balance of evidence is not sufficiently compelling to justify mandatory restrictions on any of the activities considered in this review. However, given some uncertainties in the evidence base and the apparent absence of important beneficial effects, it may be prudent to advise against long working hours, prolonged standing and heavy physical work, particularly late in pregnancy. Our review identifies several priorities for future investigation.

Validation of a food-frequency questionnaire for use in pregnancy

Objectives

As a part of an ongoing project to develop a nutritional screening tool, we evaluated the performance of a semi-quantitative food-frequency questionnaire (FFQ) in terms of validity in a Sheffield Caucasian pregnant population using two different statistical approaches – the correlation coefficient and the limits of agreement (LOA). The FFQ was designed specifically for pregnant women and previously used in a large-scale study.

Design

A validation study.

Setting

A community-based field study of a general population of pregnant women booked for their first antenatal appointment at the Jessop Wing, Royal Hallamshire Hospital, Sheffield, UK.

Subjects

One hundred and twenty-three women of different socio-economic status, aged between 17 and 43 years, provided complete dietary data.

Results

The validity of the FFQ was tested against a series of two 24-hour recalls. As expected, the intakes of all examined nutrients, except for iodine, carotene, vitamin E, biotin, vitamin C and alcohol, were higher when determined by the FFQ than when determined by 24-hour recall. Pearson's correlation coefficient between the two methods ranged from 0.19 (added sugar, zinc) to 0.47 (Englyst fibre). The LOA were broader for some of the nutrients, e.g. protein, Southgate fibre and alcohol, and an increasing lack of agreement between the two methods was identified with higher dietary intakes.

Conclusions

The FFQ gave useful estimates of the nutrient intakes of Caucasian pregnant women and appears to be a valid tool for categorising pregnant women according to dietary intake. The FFQ performed well for most nutrients and had acceptable agreement with the 24-hour recall.

Socioeconomic inequalities in very preterm birth rates

AIMS

To investigate the extent of socioeconomic inequalities in the incidence of very preterm birth over the past decade.

METHODS

Ecological study of all 549 618 births in the former Trent health region, UK, from 1 January 1994 to 31 December 2003. All singleton births of 22(+0) to 32(+6) weeks gestation (7 185 births) were identified from population surveys of neonatal services and stillbirths. Poisson regression was used to calculate incidence of very preterm birth (22-32 weeks) and extremely preterm birth (22-28 weeks) by year of birth and decile of deprivation (child poverty section of the Index of Multiple Deprivation).

RESULTS

Incidence of very preterm singleton birth rose from 11.9 per 1000 births in 1994 to 13.7 per 1000 births in 2003. Those from the most deprived decile were at nearly twice the risk of very preterm birth compared with those from the least deprived decile, with 16.4 per 1000 births in the most deprived decile compared with 8.5 per 1000 births in the least deprived decile (incidence rate ratio 1.94; 95% CI (1.73 to 2.17)). This deprivation gap remained unchanged throughout the 10-year period. The magnitude of socio-economic inequalities was the same for extremely preterm births (22-28 weeks incidence rate ratio 1.94; 95% CI (1.62 to 2.32)).

CONCLUSIONS

This large, unique dataset of very preterm births shows wide socio-economic inequalities that persist over time. These findings are likely to have consequences on the burden of long-term morbidity. Our research can assist future healthcare planning, the monitoring of socio-economic inequalities and the targeting of interventions in order to reduce this persistent deprivation gap.

Determinants of birthweight inequalities: population-based study

BACKGROUND

The aim of this paper is to study the whole spectrum of birthweight in a population-based birth cohort in order to document the role played by social factors, which complement physiological and behavioural factors, in the development of birthweight inequalities at the population level.

METHODS

The analyses were performed with data from the 'Quebec Longitudinal Study of Child Development 1998-2002 (QLSCD)'. The study follows a representative sample (n = 2103) of the children born in 1998 in the Canadian province of Québec.

RESULTS

Multivariate analyses adjusted for gestational age and mother's age indicate that mean birthweight was higher for boys than girls; improved with birth rank, mother's body mass index (BMI), and family socioeconomic status; and was lower for children of smoking mothers. Compared with children born to non-smoking mothers of higher socioeconomic status, the odds of having a low birthweight were between 6 and 12 times higher for children born to smoking mothers of lower or middle socioeconomic status. When maternal smoking status and mother's BMI are combined, socioeconomic status could still be seen to have a positive effect on mean birthweight except for overweight or obese smoking mothers, among whom the relationship between socioeconomic status and mean birthweight was reversed. In families of lower socioeconomic status, maternal smoking was the most important factor in birthweight inequalities, and in families of higher socioeconomic status, mother's BMI was the most important factor in birthweight inequalities.

CONCLUSION

This research is not only important for children in developed nations, but also for those in developing countries, where high birthweight and obesity are becoming more prevalent.

Social class inequalities in perinatal outcomes: Scotland 1980-2000

OBJECTIVE

To examine social class inequalities in adverse perinatal events in Scotland between 1980 and 2000 and how these were influenced by other maternal risk factors.

DESIGN

Population based study using routine maternity discharge data.

SETTING

Scotland.

PARTICIPANTS

All women who gave birth to a live singleton baby in Scottish hospitals between 1980 and 2000 (n=1,282,172).

MAIN OUTCOME MEASURES

Low birth weight (LBW), preterm birth, and small for gestational age (SGA).

RESULTS

The distribution of social class changed over time, with the proportion of mothers with undetermined social class increasing from 3.9% in 1980-84 to 14.8% in 1995-2000. The relative index of inequality (RII) decreased during the 1980s for all outcomes. The RII then increased between the early and late 1990s (LBW from 2.09 (95%CI 1.97, 2.22) to 2.43 (2.29, 2.58), preterm from 1.52 (1.44, 1.61) to 1.75 (1.65, 1.86), and SGA from 2.28 (2.14, 2.42) to 2.49 (2.34, 2.66) respectively). Inequalities were greatest in married mothers, mothers aged over 35, mothers taller than 164 cm, and mothers with a parity of one or more. Inequalities were also greater by the end of the 1990s than at the start of the 1980s for women of parity one or more and for mothers who were not married.

CONCLUSION

Despite decreasing during the 1980s, inequalities in adverse perinatal outcomes increased during the 1990s in all strata defined by maternal characteristics.

The role of mediating factors in the association between social deprivation and low birth weight in Germany

This study examines whether the association between social inequalities and low birth weight (LBW) (occurring in both pre- and full-term births) in Germany can be explained by several potentially confounding factors. These include maternal age, occupational status, marital status, nationality, employment status, smoking, prenatal care, psychosocial stress, obesity, short stature, short inter-pregnancy interval, chronic conditions, and several obstetrical risk factors such as pregnancy induced hypertension. We also examined how the risk for LBW varies over time within each socioeconomic group. We analyzed routinely collected perinatal data on singletons born in the federal state of Lower Saxony, Germany, in 1990, 1995, and 1999 (n = 182,444). After adjustment for all potentially confounding factors in multivariate logistic regression models, working class women, unemployed women, single mothers, and women over 39 years of age were at increased risk for pre- and full-term LBW infants. Migrant status was not related to LBW. We examined variations in the risk for LBW over time within groups, using the 1990 birth cohort as the referent group for the 1995 and 1999 birth cohorts. Compared to 1990, in 1999 women aged 19-34 years, housewives, unemployed women, women of German nationality and women with partners had higher risks for pre- and full-term LBW infants; the eldest subgroup had lower risks for LBW after adjustment for confounding factors. The factors we examined partly explain the social inequalities in LBW occurring in pre- and full-term infants. The subgroups with higher rates of LBW in 1999 compared to 1990, included women experiencing childbirth in an optimal stage of life or in a privileged social context. Public health policies in Germany should target social inequalities contributing to the aetiology of LBW and to the factors that result in increased LBW rates.

A feeling of well-being accompanied by a period of prosperity and birthweight in Chile: a possible link?

The aims of the study were to describe the trend in birthweight from 1985 to 2000 in Chile and ascertain the possible factors that may explain the changes in birthweight during the period. We used time series of birthweight and length at birth of all live births (n > 4,000,000). Multivariable regression analyses were carried out to assess whether the gender of the newborn, maternal education, maternal age and marital status could explain the trend in the total time series and by period. Birthweight adjusted for gestational age was analysed in terms of grams and Z scores. There was an increase in birthweight of 100 g between 1989 and 1994 that coincided with the re-establishment of democracy and economic growth in Chile. The changes in birthweight were not explained by the available independent variables and trends of caesarean section, maternal obesity and post-mature deliveries over the period. The birthweight difference between mothers with university education and those with primary education was 0.2 Z scores (equivalent to 110 g) in 1985 and was greatly reduced by 2000 (equivalent to 40 g). A positive sense of social well-being and economic growth may have influenced an increase in birthweight between 1989 and 1994 as socio-economic growth preceded and continued after the period of increasing birthweight. Our study showed a remarkable decrease in the differences in birthweight by educational level not shown in other countries of similar wealth.

Changing patterns of inequality in birthweight and its determinants: a population-based study, Scotland 1980-2000

Birthweight is used as an indicator of individual and population health and is known to be strongly correlated with adult cardiovascular disease. This paper uses routinely collected maternity discharge data from Scotland between 1980 and 2000 to look at birthweight trends and the changes in the distribution of maternal risk factors for birthweight. We also examine the contributions of each of the risk factors to birthweight trends and investigate whether there has been a reduction in inequality in birthweight over time. Data from 1,282,172 singleton live births were used in the analysis. Both mean birthweight and low birthweight (LBW:<2500 g) were used as outcomes. The risk factors studied were maternal age, parity, maternal height, marital status and occupational social class of the father. The slope and relative indices of inequality were used to measure the change in inequalities over time. Mean birthweight increased from 3320 g in 1980 to 3410 g in 2000, while the percentage LBW decreased slightly from 5.7% in 1980 to 5.4% in 2000. The prevalence of many risk factors changed; there has been an increase in the proportion of older mothers, single mothers, taller mothers and mothers with undetermined social class. Although most risk factors had a significant change in effect over time, the inequalities in birthweight between groups did not appear to diminish over time. Both the slope and relative index of inequality had a quadratic relationship over time, with the inequalities in birthweight being greatest in the early 1980s and late 1990s.