Decrement In Birth Weight Research Articles

Prenatal exposure to air pollutant mixtures and birthweight in the upstate KIDS cohort

BackgroundSingle-pollutant models have linked prenatal PM2.5 exposure to lower birthweight. However, analyzing air pollutant mixtures better captures pollutant interactions and total effects. Unfortunately, strong correlations between pollutants restrict traditional methods. ObjectivesWe explored the association between exposure to a mixture of air pollutants during different gestational age windows of pregnancy and birthweight. MethodsWe included 4,635 mother-infant dyads from a New York State birth cohort born 2008–2010. Air pollution data were sourced from the EPA’s Community Multiscale Air Quality model and matched to the census tract centroid of each maternal home address. Birthweight and gestational age were extracted from vital records. We applied linear regression to study the association between prenatal exposure to PM2.5, PM10, NOX, SO2, and CO and birthweight during six sensitive windows. We then utilized Bayesian kernel machine regression to examine the non-linear effects and interactions within this five-pollutant mixture. Final models adjusted for maternal socio-demographics, infant characteristics, and seasonality. ResultsSingle-pollutant linear regression models indicated that most pollutants were associated with a decrement in birthweight, specifically during the two-week window before birth. An interquartile range increase in PM2.5 exposure (IQR: 3.3 µg/m3) from the median during this window correlated with a 34 g decrement in birthweight (95 % CI: −54, −14), followed by SO2 (IQR: 2.0 ppb; β: −31), PM10 (IQR: 4.6 µg/m3; β: −29), CO (IQR: 60.8 ppb; β: −27), and NOX (IQR: 7.9 ppb; β: −26). Multi-pollutant BKMR models revealed that PM2.5, NOX, and CO exposure were negatively and non-linearly linked with birthweight. As the five-pollutant mixture increased, birthweight decreased until the median level of exposure. DiscussionPrenatal exposure to air pollutants, notably PM2.5, during the final two weeks of pregnancy may negatively impact birthweight. The non-linear relationships between air pollution and birthweight highlight the importance of studying pollutant mixtures and their interactions.

Weekly prenatal PM2.5 and NO2 exposures in preterm, early term, and full term infants: Decrements in birth weight and critical windows of susceptibility

BackgroundPrevious studies have observed associations between birth weight and prenatal air pollution exposure, but there is not consensus on timing of critical windows of susceptibility. ObjectiveWe estimated the difference in birth weight among preterm, early term and full term births associated with weekly exposure to PM2.5 and NO2 throughout gestation. MethodsWe included all singleton live births in the Lower Peninsula of Michigan (United States) between 2007 and 2012 occurring at or after 32 weeks gestational age (n = 497,897). Weekly ambient PM2.5 and NO2 concentrations were estimated at maternal residences using 1-km gridded data from ensemble-based models. We utilized a distributed lag nonlinear model to estimate the difference in birth weight associated with weekly exposures from the last menstrual period (week 0) through 31 weeks gestation for preterm births; through 36 weeks gestation for early term births; and through 38 weeks gestation for full term births. ResultsIn single-pollutant models, a 5 μg/m3 increase in PM2.5 exposure was associated with a reduction in birth weight among preterm births (−37.1 g [95% confidence interval [CI]: 60.8 g, −13.5 g]); early term births (−13.5 g [95% CI: 26.2 g, −0.67 g]); and full term births (−8.23 g [95% CI: 15.8 g, −0.68 g])]. In single-pollutant models, a 10 ppb increase in NO2 exposure was associated with a −11.7 g (95% CI: 14.46 g, −8.92 g) decrement in birth weight among full term births only. In models co-adjusted for PM2.5 and NO2, PM2.5 exposure was associated with reduced birth weight among preterm births (−36.9 g [95% CI: 61.9 g, −11.8 g]) and NO2 exposure was associated with reduced birth weight among full term births (−11.8 g [95% CI: 14.7 g, −8.94 g]). The largest decrements in birth weight were associated with PM2.5 exposure between approximately 10 and 26 weeks of pregnancy; for NO2 exposure, the largest decrements in birth weight in full term births were associated with exposure between weeks 6–18. ConclusionWe observed the largest and most persistent adverse associations between PM2.5 exposure and birth weight in preterm infants, and between NO2 exposure and birth weight in full term infants. Exposure during the first half of pregnancy had a greater impact on birthweight.

Maternal nicotine metabolism moderates the impact of maternal cigarette smoking on infant birth weight: A Collaborative Perinatal Project investigation

BackgroundMaternal cigarette smoking is an important modifiable risk factor for low birth weight in the US. We investigated the maternal nicotine metabolite ratio (NMR; trans-3’-hydroxycotinine/cotinine) – a genetically-informed biomarker of nicotine clearance – as a moderator of links between prenatal cigarette use and birth weight. We also explored the role of race in these associations. MethodsParticipants were 454 pregnant women (Mage = 25 years; 11% Black) who smoked cigarettes and their 537 infants from the Collaborative Perinatal Project. Cigarettes smoked per day were assessed at each prenatal visit; maternal NMR was assayed from third trimester serum. Birth weight was obtained from medical records. Generalized estimating equations were used to evaluate associations between cigarette smoking, NMR, race, and birth weight. ResultsNMR moderated continuous associations between cigarettes per day over pregnancy and infant birth weight (p = .025). Among women who smoked at moderate levels (<15 cigarettes per day), those with slower NMR showed ~50–100 g decrements in birth weight versus those with faster NMR., while there were no significant associations between NMR and birth weight among women who smoked 15+ cigarettes per day. Although effects of NMR on birthweight were similar for Black and white women, Black women showed significantly slower NMR (p < .001). ConclusionsThis is the first demonstration that the maternal nicotine metabolism phenotype moderates associations between maternal smoking during pregnancy and birth weight. Infants of women with slower nicotine metabolism – including disproportionate representation of Black women – may be at heightened risk for morbidity from maternal smoking.

Critical Time Windows for Air Pollution Exposure and Birth Weight in a Multicity Canadian Pregnancy Cohort.

Maternal prenatal exposure to air pollution has been associated with adverse birth outcomes. However, previous studies focused on a priori time intervals such as trimesters reported inconsistent associations. We investigated time-varying vulnerability of birth weight to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) using flexible time intervals. We analyzed 1,300 live, full-term births from Maternal-Infant Research on Environmental Chemicals, a Canadian prospective pregnancy cohort spanning 10 cities (2008-2011). Daily PM2.5 and NO2 concentrations were estimated from ground-level monitoring, satellite models, and land-use regression, and assigned to participants from pre-pregnancy through delivery. We developed a flexible two-stage modeling method-using a Bayesian Metropolis-Hastings algorithm and empirical density threshold-to identify time-dependent vulnerability to air pollution without specifying exposure periods a priori. This approach identified critical windows with varying lengths (2-363 days) and critical windows that fell within, or straddled, predetermined time periods (i.e., trimesters). We adjusted the models for detailed infant and maternal covariates. Critical windows associated with reduced birth weight were identified during mid- to late-pregnancy for both PM2.5 and NO2: -6 g (95% credible interval: -11, -1 g) and -5 g (-10, -0.1 g) per µg/m3 PM2.5 during gestational days 91-139 and 249-272, respectively; and -3 g (-5, -1 g) per ppb NO2 during days 55-145. We used a novel, flexible selection method to identify critical windows when maternal exposures to air pollution were associated with decrements in birth weight. Our results suggest that air pollution impacts on fetal development may not be adequately captured by trimester-based analyses.

66Adverse birth outcomes associated with ambient air pollution at levels below air quality guidelines

Abstract Background Gaps exist concerning the relationship between maternal exposure to air pollution and birth outcomes, including the importance of low-level exposure. We aimed to explore the association between maternal exposure to ambient nitrogen dioxide (NO2) and fine particulate matter (PM2.5) and selected birth outcomes in Victoria, Australia. Methods We included all births occurring in Victoria, Australia from 1st March 2012 to 31st December 2015 using routinely collected government data. Outcomes included birthweight, small for gestational age (SGA), term low birth weight (tLBW), large for gestational age, and spontaneous preterm birth. Annual ambient NO2 and PM2.5 was assigned to maternal residence at birth. Maternal, meteorological and temporal variables were included in final log-binomial models. Results There were 285,594 births. Average annual ambient NO2 exposure was 6.0 parts per billion (ppb, IQR 3.9 ppb) and PM2.5 was 6.9 µg/m3 (IQR 1.3). IQR increases in ambient NO2 and PM2.5 were associated with fetal growth restriction, including decrements in birth weight, increased risk of SGA and tLBW. Women with gestational diabetes and hypertensive disorders of pregnancy had greater decrements in birth weight associated with exposure. Conclusions Maternal exposure to low-level ambient air pollution at levels below national and international air quality guidelines was associated with fetal growth restriction. Key messages Exposure to low-level ambient air pollution was associated with fetal growth restriction and women with obstetric complications were more susceptible. These findings may inform iterative revisions of air quality guidelines.

Chronic neighborhood stressors can modify the effect of nitrogen dioxide on term birthweight in New York City

Urban air pollution exposures are associated with decreased newborn birthweight and developmental impairments, potentially with stronger impacts in communities of lower socioeconomic position (SEP). Here, we examined 28 community stressors - which vary with neighborhood SEP - as potential modifiers of the nitrogen dioxide (NO2)-birthweight association in New York City (NYC). We examined birth records data on 245,345 live births from 2007 to 2010 and administrative data on 28 social stressors aggregated to United Hospital Fund (UHF) areas (n = 34), categorized into quartiles. Residence-specific NO2 exposure concentrations, averaged over each pregnancy, were created using NYC Community Air Survey (NYCCAS) and daily EPA regulatory data. We applied linear mixed-effects modeling using UHF as a clustering variable and tested interactions between social factors and NO2. We observed an averaged 12.6-g (SE = 2.72) decrease in newborn birthweight per IQR increase in NO2 (IQR= 6.24 ppb). We also observed significant decrements in birthweight with higher stressor exposures (main effects), including significant decreases across quartiles for assault rates (p=.02 for trend across quartiles), child abuse (p=.02), murder (p=.007), robbery (p=.03), and perceived lack of safety (p=.02). Interaction analyses revealed weaker NO2-birthweight associations in areas with higher community stressors - including higher assault rates (p=.03), murder (p=.03), robbery (p=.04), or perceived lack of safety (p=.02). We found that birthweights in higher-pollution/higher-violence communities were substantially lower, on average, than in lower-pollution/lower-violence communities. These differences were driven, however, by strong direct associations between violence and birthweight; with very high violence exposures, impacts of pollution were dampened. Non-violent social stressors generally did not confer lower birthweights, nor did they substantially alter NO2 effects. Our results suggest complex interactions among stressors and pollutants, including potential saturation effects at the high end of violence exposures. Research in larger datasets and more flexible methods are needed to characterize non-linear interactions.

Adverse birth outcomes in Victoria, Australia in association with maternal exposure to low levels of ambient air pollution

BackgroundThe relationship between maternal exposure to air pollution and birth outcomes is not well characterised where ambient air pollution is relatively low. ObjectivesWe aimed to explore the association between maternal exposure to ambient nitrogen dioxide (NO2) and fine particulate matter (PM2.5) and a range of birth outcomes in Victoria, Australia. Secondary aims were to explore whether obstetric conditions, such as gestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy, were effect modifiers in observed relationships. MethodsWe included all singleton births occurring in Victoria, Australia from 1st March 2012 to 31st December 2015 using routinely collected government data. Outcomes included birth weight, small for gestational age (SGA), term low birth weight (tLBW), large for gestational age (LGA), and spontaneous preterm birth (sPTB). We estimated exposure to annual ambient NO2 and PM2.5 concentrations, assigned to maternal residence at time of birth. Confounders included maternal, meteorological and temporal variables. Multivariable linear regression and log-binomial regression were used for continuous and dichotomous outcomes, respectively. ResultsThere were 285,594 births during the study period. Average NO2 exposure was 6.0 parts per billion (ppb, median 5.6; interquartile range (IQR) 3.9) and PM2.5 was 6.9 μg/m3 (median 7.1, IQR 1.3). IQR increases in ambient NO2 and PM2.5 were associated with fetal growth restriction, including decrements in birth weight (NO2 β −22.8 g; 95%CI -26.0, −19.7; PM2.5 β −14.8 g; 95%CI -17.4, −12.2) and increased risk of SGA (NO2 RR 1.08; 95%CI 1.06, 1.10; PM2.5 RR 1.05; 95%CI 1.04, 1.07) and tLBW (NO2 RR 1.06; 95%CI 1.01, 1.10; PM2.5 RR 1.04; 95%CI 1.03, 1.08). Women with GDM and hypertensive disorders of pregnancy had greater decrements in birth weight in association with pollutant exposure. DiscussionIn this exploratory study using an annual metric of exposure, maternal exposure to low-level ambient air pollution was associated with fetal growth restriction, which carries substantial public health implications.

The Effects of Parity on the Birth Weight in Fengtai District, Beijing from 2015 to 2017

Abstract Objectives The aim of the current study was to explore the effects of parity on the birth weight in Fengtai district, Beijing, around the two-child policy complete implementation in China. Methods This is a retrospective study, with 57,987 live, singleton birth selected from Fengtai district, Beijing from 2015 to 2017. Data were divided into primiparous (n = 39,737) and secundiparous (n = 18,250), both maternal factors and neonatal outcomes were analyzed. ANOVA and Chi-square analysis were used to compare the difference within and between groups, and multiple linear regression models were used to assess the effects of parity on the birth weight, adjusting for potential confounders. Results Comparing 2017 to 2015, the number of primiparous and secundiparous was increased by 43.4% and 155.3%, respectively. The average birth weight was heavier in secundiparous than primiparous (3391.95 ± 463.67 g vs 3344.66 ± 463.09 g, P &amp;lt; 0.001). Significant decrements in birth weight were observed in primiparous groups (18.40 ± 6.27 g, P &amp;lt; 0.05) and secundiparous (29.75 ± 9.79 g, P &amp;lt; 0.05) during the three years. No difference was found for the low birth weight ratio in primiparous (Chi-square = 1.549, P = 0.461) but was observed of a 0.7% increment in secundiparous (2.3% vs 3.0%, Chi-square = 7.741, P = 0.021) from 2015–2017. After multiple linear regression, significant positive correlations were observed between parity and birth weight and the β value was decreased in the three years (β2015 = 38.213; 95% CI: 22.518 to 53.908, P &amp;lt; 0.001; β2016 = 34.843; 95% CI:24.758 to 44.928, P &amp;lt; 0.001; β2017 = 25.137; 95% CI: 15.287 to 34.988, P &amp;lt; 0.001), adjusted by gender, birth length, maternal age, gestational week, number of abortion, mode of delivery, maternal education and maternal domicile. Conclusions The birth weight is higher among the secundiparous than the primiparous in Fengtai district Beijing during 2015–2017, and parity is an important factor affecting the birth weight. Funding Sources Nutrition Research Fund of Chinese Nutrition Society-Feihe Research Fund for Physical Nutrition and Health.

The relationship between birth weight and congenital heart disease at Ahmed Gasim Cardiac Centre, Bahri, Sudan

Low birth weight is a known comorbidity of congenital heart disease (CHD). This study examines the relationship between CHD and birth weight of singletons, while attempting to remove factors that influence birth weight, and assesses the impact of CHD on growth in later life. The main objective is to study the relationship between birthweight and CHD. This is a cross-sectional study of 141 samples, covering all patients who were referred to the Paediatric Echocardiography Lab at Ahmed Gasim Cardiac Centre between September and October 2016. Infants with genetic syndromes or other major extracardiac abnormalities were excluded. The findings of this study clearly demonstrate that infants with CHD are more likely to be of low birth weight than the general Sudanese population, by a factor of 2.6. Of the sample, 31.9% were born with low or very low birthweight. The mean birth weight of the cases was 2.59 kg, which is 17.3% and 542.4 g less than the national average. CHD that cause a decrement in birth weight in a descending order of severity were atrial septal defect (-721 g/23%), patent ductus arteriosus (-669 g/21%), ventricular septal defect (-610 g/19%), pulmonary stenosis (-548 g/13%) and tetralogy of Fallot (248 g/8%). Pre/postnatal growth impairment is a common feature among children with CHD. No statistically significant relationship was found between the degree of birth weight/weight to age decrement and the specific type of hemodynamic disturbance. Our results are comparable to other studies that have been undertaken. However, Sudanese patients display larger birthweight deficits than other populations.

Glyburide in Women With Mild Gestational Diabetes: A Randomized Controlled Trial.

To evaluate whether the addition of glyburide to diet therapy modifies pregnancy outcomes in women with mild gestational diabetes. Women with at least two abnormal values on a 3-hour, 100-g oral glucose tolerance test according to National Diabetes Data Group criteria and fasting values less than 105 mg/dL between 24 and 30 weeks of gestation were randomized to blinded glyburide or placebo study drug. All women were placed on a 35-kcal/kg diet and recorded four times daily capillary glucose measurements. The study drug was titrated based on weekly maternal capillary glucose values with targets of less than 95 mg/dL (5.3 mmol/L) and 120 mg/dL (6.7 mmol/L) for fasting and 2-hour postprandial glucose measurements, respectively. The primary study outcome was a 200-g birth weight decrement in neonates of women treated with glyburide. The sample size estimate for this outcome was 334 total randomized women with a one-to-one allocation. A total of 395 women were enrolled at a single center between September 2008 and October 2012. Women treated with glyburide had a significantly greater decline in fasting glucose values over the course of therapy. However, there was no difference in the primary study outcome. Specifically, the mean birth weight was 33 g lower in the group treated with glyburide (P=.52). Although not powered to examine all outcomes associated with gestational diabetes, treatment with glyburide did not affect need for operative delivery, shoulder dystocia, clavicular fracture, Erb's palsy, or neonatal hypoglycemia. Four women in each group required insulin. The addition of glyburide to diet therapy significantly improved maternal glycemic control over time when compared with placebo. However, adding glyburide to diet did not decrease birth weight or improve maternal or neonatal outcomes in women with mild gestational diabetes. ClinicalTrials.gov, www.clinicaltrials.gov, NCT00744965. I.

Relationship of birth weight with congenital cardiovascular malformations in a population-based study.

A known comorbidity of congenital cardiovascular malformations is low birth weight, but the reasons for this association remain obscure. This retrospective study examines the relationship between congenital cardiovascular malformations and the birth weight of singletons, taking into account differences in gestational age and other factors. Using data from the retrospective, population-based Baltimore-Washington Infant Study, six types of congenital cardiovascular malformations were investigated in comparison with controls (n=3519) through linear regression: d-transposition of the great arteries (n=187), other conotruncal heart defects (n=361), endocardial cushion defects (n=281), left heart obstructive lesions (n=507), atrial septal defects (n=281), and membranous ventricular septal defects (n=622). Infants with conotruncal heart defects (-218 g), endocardial cushion defects with Down syndrome (-265 g), endocardial cushion defects without Down syndrome (-194 g), left heart obstructive lesions (-143 g), atrial septal defects (-150 g), and membranous ventricular septal defects (-127 g) showed significant birth weight deficits, adjusting for gestational age, and other covariates. Infants with d-transposition of the great arteries (-67 g) did not show significant birth weight deficits compared with the control group. The degree of birth weight decrement appears to be highly related to the specific type of congenital cardiovascular malformation. As a whole, these infants do not exhibit low birth weights solely because of being premature, and thus other mechanisms must underlie these associations.

Prevalence and determinants of low birth weight and prematurity among rural, urban, and indigenous tribal communities in India.

Background: Birth weight and gestational age are important determinants of child survival and development. Developing countries like India have been recording very high prevalence (30-40%) of low birth weight (LBW) and a relatively low prevalence of prematurity (~10%). Aim: Examine the role of multiple environmental factors on neonatal outcomes in India. Methods: Utilizing a population-based, 6884 mother-baby cohort spread across rural, tribal, and urban areas of Odisha, we have recently launched the IMMENSE (Impact of Maternal Environmental and Socio Economic - status on child health and development) study where data are being collected on maternal variables and on type of household cooking fuel, direct smoke and ETS, drinking water, alcohol use, and exposure to occupational/industrial/ and mining and pesticides and fertilizers, New births are also being added to this cohort. Results: Average gestational age in this population was 32 weeks and birth weight was 2.53 kg. A total of 28% babies were premature; 13.3% ? 35 weeks, and an additional 14.8% between 36-40 weeks of gestation. The decrements in birth weight were attenuated using multivariate analyses after adjusting the maternal and socioeconomic factors. The environmental factors significantly associated with LBW were biomass fuel/household air pollution (OR-2.51), drinking water (OR-2.34), proximity to industry/highway (OR-1.98), domestic/agricultural pesticide use (OR-1.91), smoking/ETS (OR-1.85), and alcohol use (OR-1.39). Although small in number, newborns in households using liquid petroleum gas did not seem to have better outcomes. Conclusions: This study demonstrates an unexpected shift from low birth weight preponderance to an increase in prematurity in India (similar to the western countries). While improved maternal health over the decades might have contributed to reduction in LBW, new and significant environmental pollution may be contributing to preterm births. The IMMENSE study was funded by a grant from the University of Nebraska Foundation.

Influence of spatial heterogeneity in socioeconomic deprivation on birth outcomes and air pollution epidemiology in New York City, USA

Background: Numerous studies have linked area-level socioeconomic deprivation with adverse birth outcomes. Deprivation is often operationalized as a composite index, which efficiently combines diverse components of socioeconomic position (SEP), but also may obscure spatial heterogeneity in variable distributions, potentially biasing epidemiological models. Aims: We aimed to build (and test) a deprivation index reflecting spatial heterogeneity in New York City (NYC), to include with fine-scale air pollution in birth outcomes models. Methods: We explored intra-urban spatial variability across contextual SEP factors previously associated with birth outcomes (n=20). We applied spatially-stratified Principle Components Analysis (borough-level) to reflect spatially-varying prevalence and combinations of SEP factors in a composite deprivation score. For comparison, we calculated a crude citywide index following the same data reduction process. Results: The spatial deprivation index retained seven area-based SEP variables (college degree, unemployment, management/professional occupation, residential crowding, poverty, households receiving public assistance, non-white racial composition), explaining 55% of overall variance in SEP factors. The crude index included fewer and somewhat different SEP variables, explaining 41% of overall variance, and correlated with the spatial index at r=0.70. Residential outdoor PM2.5 exposure was differentially correlated with the spatial (r=-0.11) and crude (r=0.02) indices. After adjusting for individual covariates and exposure to PM2.5, spatial and crude deprivation indices were associated with 5.32g and 6.56g decrements in birth weight per IQR change in SEP index – small changes, yet within the range of concern for air pollution effects on birth outcomes. Conclusions: Spatially-informed data reduction techniques can improve estimation of area-level deprivation, and elucidate potential confounding and bias in epidemiological analyses.

Associations of Prenatal Exposure to Organophosphate Pesticide Metabolites with Gestational Age and Birth Weight

Background: Prenatal exposure to organophosphate (OP) insecticides, a widely used class of pesticides, may be associated with decreased gestational age and lower birth weight. Single nucleotide polymorphisms in paroxanase (PON1) enzyme genotypes may modify the relationships between OP exposure and perinatal outcomes.Objective: We examined the relationship of prenatal OP insecticide exposure, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, with gestational age and birth weight.Methods: We measured the concentrations of six nonspecific DAP metabolites of OP insecticides in two maternal spot urine samples collected in a prospective birth cohort. We performed multivariable regression to examine associations between the sum of six DAP concentrations (ΣDAP) with gestational age and birth weight. We also examined whether these associations differed according to infant PON1192 and PON1–108 genotypes.Results: Among 306 mother–infant dyads, a 10-fold increase in ΣDAP concentrations was associated with a decrease in covariate-adjusted gestational age [–0.5 weeks; 95% confidence interval (CI): –0.8, –0.1] and birth weight (–151 g; CI: –287, –16); the decrements in birth weight were attenuated after adjusting for gestational age. The relationship between ΣDAP concentrations and gestational age was stronger for white (–0.7 weeks; CI: –1.1, –0.3) than for black (–0.1 weeks; 95% CI: –0.9, 0.6) newborns. In contrast, there was a greater decrease in birth weight with increasing urinary ΣDAP concentrations for black (–188 g; CI: –395, 19) than for white (–118 g; CI: –296, 60) newborns. Decrements in birth weight and gestational age associated with ΣDAP concentrations were greatest among infants with PON1192QR and PON–108CT genotypes.Conclusions: Prenatal urinary ΣDAP concentrations were associated with shortened gestation and reduced birth weight in this cohort, but the effects differed by race/ethnicity and PON1192/108 genotypes.

Neighborhood effects on birthweight: An exploration of psychosocial and behavioral pathways in Baltimore, 1995–1996

Neighborhood characteristics have been proposed to influence birth outcomes through psychosocial and behavioral pathways, yet empirical evidence is lacking. Using data from an urban, low-income sample, this study examined the impact of the neighborhood environment on birthweight and evaluated mediation by psychosocial and behavioral factors. The sample included 726 women who delivered a live birth at Johns Hopkins Hospital in Baltimore, Maryland, USA between 1995 and 1996. Census-tract data were used to create a principal component index of neighborhood risk based on racial and economic stratification (% Black, % poverty), social disorder (violent crime rate), and physical deterioration (% boarded-up housing) ( α = 0.82). Information on sociodemographic, psychosocial, and behavioral factors was gathered from a postpartum interview and medical records. Random intercept multilevel models were used to estimate neighborhood effects and assess potential mediation. Controlling for sociodemographic characteristics, a standard deviation increase in neighborhood risk conferred a 76 g birthweight decrement. This represents an approximate 300 g difference between the best and worst neighborhoods. Although stress (daily hassles), perceived locus-of-control, and social support were related to birthweight, their adjustment reduced the neighborhood coefficient by only 12%. In contrast, the neighborhood effect was reduced by an additional 30% and was no longer statistically significant after adjustment for the behavioral factors of smoking, drug use, and delayed prenatal care. These findings suggest that neighborhood factors may influence birthweight by shaping maternal behavioral risks. Thus, neighborhood level interventions should be considered to address multiple maternal and infant health risks. Future studies should examine more direct measures of neighborhood stress, such as perceived neighborhood disorder, and evaluate alternative mechanisms by which neighborhood factors influence behavior (e.g., social norms and access to goods and services).

Maternal oxygen delivery is not related to altitude‐ and ancestry‐associated differences in human fetal growth

Fetal growth is reduced at high altitude, but the decrease is less among long-resident populations. We hypothesized that greater maternal uteroplacental O(2) delivery would explain increased fetal growth in Andean natives versus European migrants to high altitude. O(2) delivery was measured with ultrasound, Doppler and haematological techniques. Participants (n=180) were pregnant women of self-professed European or Andean ancestry living at 3600 m or 400 m in Bolivia. Ancestry was quantified using ancestry-informative single nucleotide polymorphism. The altitude-associated decrement in birth weight was 418 g in European versus 236 g in Andean women (P<0.005). Altitude was associated with decreased uterine artery diameter, volumetric blood flow and O(2) delivery regardless of ancestry. But the hypothesis was rejected as O(2) delivery was similar between ancestry groups at their respective altitudes of residence. Instead, Andean neonates were larger and heavier per unit of O(2) delivery, regardless of altitude (P<0.001). European admixture among Andeans was negatively correlated with birth weight at both altitudes (P<0.01), but admixture was not related to any of the O(2) transport variables. Genetically mediated differences in maternal O(2) delivery are thus unlikely to explain the Andean advantage in fetal growth. Of the other independent variables, only placental weight and gestational age explained significant variation in birth weight. Thus greater placental efficiency in O(2) and nutrient transport, and/or greater fetal efficiency in substrate utilization may contribute to ancestry- and altitude-related differences in fetal growth. Uterine artery O(2) delivery in these pregnancies was 99 +/- 3 ml min(-1), approximately 5-fold greater than near-term fetal O(2) consumption. Deficits in maternal O(2) transport in third trimester normal pregnancy are unlikely to be causally associated with variation in fetal growth.

Prenatal Cocaine Exposure and Child Welfare Outcomes

This study examines the relationship between prenatal cocaine exposure and child welfare outcomes. Seventy-six infants positive for cocaine at birth were matched to 76 negative infants. With prenatal care and maternal use of alcohol and tobacco controlled, cocaine-exposed infants had significant decrements in birth weight, length, head circumference, and depressed 5-min Apgar scores. This confirmed the health risk of prenatal cocaine exposure for the sample. Three-year follow-up data were obtained from the State Central Register and foster care records. Adjusting for prior maternal involvement with child welfare services the study groups did not differ in incidents of child maltreatment or foster care placement. These findings suggest that prenatal cocaine exposure is not a marker for abusive parenting. However, from the perspective of a cumulative risk model, the identification of cocaine-exposed infants at birth can form the starting point for the development of appropriate diagnostic and follow-up services for mother and child.

Treatment of tobacco use in preconception care.

Treatment of tobacco use in preconception care.

Maternal use of cannabis and pregnancy outcome.

To document the prevalence of cannabis use in a large sample of British women studied during pregnancy, to determine the association between cannabis use and social and lifestyle factors and assess any independent effects on pregnancy outcome. Self-completed questionnaire on use of cannabis before and during pregnancy. Over 12,000 women expecting singletons at 18 to 20 weeks of gestation who were enrolled in the Avon Longitudinal Study of Pregnancy and Childhood. Any association with the use of cannabis before and during pregnancy with pregnancy outcome was examined, taking into account potentially confounding factors including maternal social background and other substance use during pregnancy. Late fetal and perinatal death, special care admission of the newborn infant, birthweight, birth length and head circumference. Five percent of mothers reported smoking cannabis before and/or during pregnancy; they were younger, of lower parity, better educated and more likely to use alcohol, cigarettes, coffee, tea and hard drugs. Cannabis use during pregnancy was unrelated to risk of perinatal death or need for special care, but, the babies of women who used cannabis at least once per week before and throughout pregnancy were 216 g lighter than those of non-users, had significantly shorter birth lengths and smaller head circumferences. After adjustment for confounding factors, the association between cannabis use and birthweight failed to be statistically significant (P = 0.056) and was clearly non-linear: the adjusted mean birthweights for babies of women using cannabis at least once per week before and throughout pregnancy were 90 g lighter than the offspring of other women. No significant adjusted effects were seen for birth length and head circumference. The results of this study suggest that the use of cannabis during pregnancy was not associated with increased risk of perinatal mortality or morbidity in this sample. However, frequent and regular use of cannabis throughout pregnancy may be associated with small but statistically detectable decrements in birthweight.

The effect of prenatal dietary protein intake on birth weight

From 1940 to 1980, protein deficiency was implicated in depressed fetal growth and impaired infant development. Consequently, increasing protein intake in pregnancy was recommended. In 1980, a randomized controlled trial found high protein supplements to be associated with depressed birth weight in low-income pregnant women. The objective of this study was to assess the role of dietary protein during pregnancy in women consuming a self-selected diet. The relation between dietary protein intake and pregnancy outcome was explored in an observational, longitudinal study of low income, mostly urban women. Protein intake was estimated using the average of two 24-hour dietary recalls, the first generally completed between months 4 to 6 and the second in month 8 of pregnancy. Hierarchical multiple regression analyses were conducted, adjusted for maternal, infant and socio-demographic characteristics and for duration of gestation and maternal energy intake. This study found that mean protein intake ≥85 g/day was associated with a 71 g decrement in birth weight ( n = 2163, p = 0.009) compared to intermediate (50–84.9 g/day) average protein intake. About 36% of the women studied reported mean intakes of ≥85 g protein daily during pregnancy, whereas only 12% had low protein intakes (<50 g/day). Thus, the negative effect of high protein intake on birth weight may have considerable public health significance and should not be encouraged.