Polydrug Use During Pregnancy and Preterm Birth in a Low-Income, Multiethnic Birth Cohort, Boston, 1998-2018.

OBJECTIVE: The opioid epidemic in the United States increasingly affects women of reproductive age and has resulted in a rise in concurrent polydrug use. The objective of this study was to investigate the effect of this polydrug use on preterm birth in a multiethnic birth cohort. METHODS: We analyzed data from 8261 mothers enrolled in the Boston Birth Cohort from 1998 to 2018 in Boston, Massachusetts. We grouped substances used during pregnancy based on their primary effects (stimulant or depressant) and assessed independent and combined associations with smoking on preterm birth. RESULTS: Of 8261 mothers, 131 used stimulant drugs and 193 used depressant drugs during pregnancy. The preterm birth rate was 27.5% (2271 of 8261) in the sample. Mothers who smoked had 35% increased odds of preterm birth across adjusted models. Mothers who used stimulant drugs without smoking were not at increased risk of preterm delivery compared with mothers who used neither (odds ratio [OR] = 0.69; 95% confidence interval [CI], 0.19-1.98), whereas mothers who used depressant drugs without smoking had more than twice the odds of having preterm delivery (OR = 2.31; 95% CI, 1.19-4.44), and infants were at risk of a 1-week reduction in gestational age (OR = -1.05; 95% CI, -2.07 to -0.03). Concurrently smoking and using depressant drugs was associated with increased odds of preterm birth (OR = 1.83; 95% CI, 1.28-2.61), as was concurrently smoking and using stimulant drugs (OR = 1.73; 95% CI, 1.14-2.59). CONCLUSIONS: Using stimulant drugs and depressant drugs during pregnancy is a risk factor for preterm birth. The individual and combined effects of using these drugs with smoking must be considered together to reduce the risk of preterm birth in the United States.

Research and policy priorities for addressing prenatal exposure to opioids in Alaska.

The current opioid crisis in Alaska and the USA will negatively affect the health and wellbeing of future generations. The increasing number of infants born with neonatal opioid withdrawal syndrome (NOWS) has had a profound impact on families, health care providers and the child welfare system. This manuscript summarises the main themes of a Symposium held in Anchorage, Alaska with health care providers, researchers, elders and public health officials that focused on identifying emerging challenges, trends and potential solutions to address the increasing number of infants and children affected by maternal opioid use. Five areas of importance for research and policy development that would direct improvement in the care of infants with NOWS in Alaska are outlined with the goal of supporting a research agenda on opioid misuse and child health across the circumpolar north. Abbreviations: NOWS - neonatal opioid withdrawal syndrome; NAS - neonatal abstinence syndrome; MAT - medication-assisted treatment; NICU - neonatal intensive care unit; OATs - opioid agonist treatments; OCS - office of children's services; ANTHC - Alaska Native Tribal Health Consortium; OUD - opioid use disorder; SBIRT - screening, brief intervention and referral to treatment; ISPCTN - IDeA States Pediatric Clinical Trials Network; NIH - National Institutes of Health; ANMC - Alaska Native Medical Center; DHSS - Department of Health and Social Services; AAPP - All Alaska Pediatric Partnership.

Morphometric analysis in ethnic neonates from multiple substance exposure.

In the United States, approximately 10% of newborn infants are exposed prenatally to alcohol and/or illicit substances. However, no studies have evaluated the compounding effects of multiple illicit substances exposure in utero as potential teratogen (s). The potential teratogenic effects of nicotine and illicit substances (e.g. cocaine, marijuana and heroin) have previously been studied but there has been no documentation of facial landmark dislocation (s). Our goal is to investigate whether morphometric analysis could differentiate facial landmark dislocations in neonates of African descent, when exposed to alcohol, nicotine and illicit substances, either singly or in combination. Craniofacial features from a cohort of 493 African-American neonates less than 48 hours of age were analyzed by Multivariate Hotelling's T2 analysis of 99 relevant facial landmark triangles. Morphometric analysis discriminated unique asymmetries in groups of certain illicit exposure(s). Neonates with multiple prenatal exposures had fewer facial landmark dislocation(s) compared to single exposures. Deviation from normal facial features has the potential to be used as a screening tool for prenatal exposure to some illicit substances.

As Long as the Breath Lasts: In Utero Exposure to Ramadan and the Occurrence of Wheezing in Adulthood.

While prenatal exposure to Ramadan has been shown to be negatively associated with general physical and mental health, studies on specific organs remain scarce. In this study, we explored whether Ramadan exposure during pregnancy affects the occurrence of wheezing, a main symptom of obstructive airway disease. Using data from the Indonesian Family Life Survey collected between 1997 and 2008 (waves 2-4), we compared wheezing occurrence among adult Muslims who had been in utero during Ramadan with that in adult Muslims who had not been in utero during Ramadan. Wheezing prevalence was higher among adult Muslims who had been in utero during Ramadan, independent of the pregnancy phase in which the exposure to Ramadan occurred. Moreover, this association tended to increase with age, being strongest among those aged about 45 years or older. This is in line with fetal programming theory, suggesting that impacts of in utero exposures often manifest only after reproductive age. Particularly strong associations were detected for smokers. The respiratory system of prenatally exposed Muslims thus seems to perform worse in mitigating later ex utero harmful influences such as smoking. This study suggests that exposure to Ramadan during pregnancy may have lasting consequences for adult lung functionality.

Associations Between Maternal Obesity and Pregnancy Hyperglycemia and Timing of Puberty Onset in Adolescent Girls: A Population-Based Study.

Early puberty is associated with adverse health outcomes. We investigated whether in utero exposure to maternal obesity is associated with daughters' pubertal timing using 15,267 racially/ethnically diverse Kaiser Permanente Northern California members aged 6-11 years with pediatrician-assessed Tanner staging (2003-2017). We calculated maternal body mass index (BMI; weight (kg)/height (m)2) during pregnancy from the electronic health record data. Using a proportional hazards model with interval censoring, we examined the associations between maternal obesity and girls' pubertal timing, as well as effect modification by race/ethnicity and mediation by prepubertal BMI. Maternal obesity (BMI ≥30) and overweight (BMI 25-29.9) were associated with earlier onset of breast development in girls (hazard ratio (HR) = 1.39 (95% confidence interval (CI): 1.30, 1.49) and HR = 1.21 (95% CI: 1.13, 1.29), respectively), after adjustment for girl's race/ethnicity, maternal age, education, parity, and smoking during pregnancy. There was interaction by race/ethnicity for associations between maternal obesity and girls' pubic hair onset: Associations were strongest among Asian and non-Hispanic white girls (HR = 1.53 (95% CI: 1.24, 1.90) and HR = 1.34 (95% CI: 1.18, 1.52), respectively) and absent for African-American girls. Adjustment for girl's prepubertal BMI only slightly attenuated associations. Our results suggest the importance of maternal metabolic factors during pregnancy in the timing of girls' puberty and potential differences in the associations by race/ethnicity.

Combined effects of prenatal exposure to polycyclic aromatic hydrocarbons and material hardship on child ADHD behavior problems.

IMPORTANCE: Polycyclic aromatic hydrocarbons (PAH) are carcinogenic and neurotoxic combustion by-products commonly found in urban air. Exposure to PAH is disproportionately high in low income communities of color who also experience chronic economic stress. OBJECTIVE: In a prospective cohort study in New York City (NYC) we previously found a significant association between prenatal PAH exposure and Attention Deficit Hyperactivity Disorder (ADHD) behavior problems at age 9. Here, we have evaluated the joint effects of prenatal exposure to PAH and prenatal/childhood material hardship on ADHD behavior problems. MATERIALS AND METHODS: We enrolled nonsmoking African-American and Dominican pregnant women in New York City between 1998 and 2006 and followed their children through 9 years of age. As a biomarker of prenatal PAH exposure, PAH-DNA adducts were measured in maternal blood at delivery and were dichotomized at the limit of detection (to indicate high vs. low exposure). Maternal material hardship (lack of adequate food, housing, utilities, and clothing) was self-reported prenatally and at multiple time points through child age 9. Latent variable analysis identified four distinct patterns of hardship. ADHD behavior problems were assessed using the Conners Parent Rating Scale- Revised. Analyses adjusted for relevant covariates. RESULTS: Among 351 children in our sample, across all hardship groups, children with high prenatal PAH exposure (high adducts) generally had more symptoms of ADHD (higher scores) compared to those with low PAH exposure. The greatest difference was seen among the children with hardship persisting from pregnancy through childhood. Although the interactions between high PAH exposure and hardship experienced at either period ("persistent" hardship or "any" hardship) were not significant, we observed significant differences in the number of ADHD symptoms between children with high prenatal PAH exposure and either persistent hardship or any hardship compared to the others. These differences were most significant for combined high PAH and persistent hardship: ADHD Index (p < 0.008), DSM-IV Inattentive (p = 0.006), DSM-IV Hyperactive Impulsive problems (p = 0.033), and DSM-IV Index Total (p = 0.009). CONCLUSION: The present findings add to existing evidence that co-exposure to socioeconomic disadvantage and air pollution in early life significantly increases the risk of adverse neurodevelopmental outcomes. They suggest the need for multifaceted interventions to protect pregnant mothers and their children.

The association between passive and active tobacco smoke exposure and child weight status among Spanish children.

OBJECTIVE: To assess the impact of passive and active tobacco smoke exposure, both pre- and postnatally, on child body mass index (BMI) and overweight. METHODS: Pregnant women were enrolled into the Spanish INMA prospective birth cohort during 1997 to 2008. Tobacco smoke exposure was assessed by questionnaire and corroborated by pre- and postnatal cotinine measurements. Children were followed up until 4 years in newer subcohorts (N = 1866) and until 14 years in one older subcohort (N = 427). Child age- and sex-specific BMI Z-scores were calculated, and generalized estimating equations were used to model their relationship with repeated measures of tobacco smoke exposure. RESULTS: Associations between prenatal passive exposure to tobacco smoke (adjusted ß = 0.15, 95% CI: 0.05-0.25) and active maternal smoking (adjusted ß = 0.20, 95% CI: 0.08-0.33) and child zBMI up to 4 years were observed. Stronger associations were observed in the older subcohort between both prenatal and child passive smoke exposure and zBMI up to 14 years. CONCLUSIONS: Evidence for an effect of both passive and maternal active smoking on child postnatal growth has been provided. Although residual confounding cannot be completely ruled out, associations were robust to adjustment for a range of lifestyle factors.

Geographic analysis of individual and environmental risk factors for hypospadias births.

BACKGROUND: Hypospadias is a relatively common birth defect affecting the male urinary tract. We explored the etiology of hypospadias by examining its spatial distribution in North Carolina and the spatial clustering of residuals from individual and environmental risk factors. METHODS: We used data collected by the North Carolina Birth Defects Monitoring Program from 2003 to 2005 to estimate local Moran's I statistics to identify geographic clustering of overall and severe hypospadias, using 995 overall cases and 16,013 controls. We conducted logistic regression and local Moran's I statistics on standardized residuals to consider the contribution of individual variables (maternal age, maternal race/ethnicity, maternal education, smoking, parity, and diabetes) and environmental variables (block group land cover) to this clustering. RESULTS: Local Moran's I statistics indicated significant clustering of overall and severe hypospadias in eastern central North Carolina. Spatial clustering of hypospadias persisted when controlling for individual factors, but diminished somewhat when controlling for environmental factors. In adjusted models, maternal residence in a block group with more than 5% crop cover was associated with overall hypospadias (odds ratio = 1.22; 95% confidence interval = 1.04-1.43); that is living in a block group with greater than 5% crop cover was associated with a 22% increase in the odds of having a baby with hypospadias. Land cover was not associated with severe hypospadias. CONCLUSION: This study illustrates the potential contribution of mapping in generating hypotheses about disease etiology. Results suggest that environmental factors including proximity to agriculture may play some role in the spatial distribution of hypospadias. Birth Defects Research (Part A) 100:887-894, 2014. © 2014 Wiley Periodicals, Inc.

Prenatal exposure to organophosphate pesticides and reciprocal social behavior in childhood.

Prenatal exposure to organophosphate pesticides (OPs) has been associated with adverse neurodevelopmental outcomes in childhood, including low IQ, pervasive developmental disorder (PDD), attention problems and ADHD. Many of these disorders involve impairments in social functioning. Thus, we investigated the relationship between biomarkers of prenatal OP exposure and impaired reciprocal social behavior in childhood, as measured by the Social Responsiveness Scale (SRS). Using a multi-ethnic urban prospective cohort of mother-infant pairs in New York City recruited between 1998 and 2002 (n=404) we examined the relation between third trimester maternal urinary levels of dialkylphosphate (ΣDAP) OP metabolites and SRS scores among 136 children who returned for the 7-9year visit. Overall, there was no association between OPs and SRS scores, although in multivariate adjusted models, associations were heterogeneous by race and by sex. Among blacks, each 10-fold increase in total diethylphosphates (ΣDEP) was associated with poorer social responsiveness (ß=5.1 points, 95% confidence interval (CI) 0.8, 9.4). There was no association among whites or Hispanics, or for total ΣDAP or total dimethylphosphate (ΣDMP) biomarker levels. Additionally, stratum-specific models supported a stronger negative association among boys for ΣDEPs (ß=3.5 points, 95% CI 0.2, 6.8), with no notable association among girls. Our results support an association of prenatal OP exposure with deficits in social functioning among blacks and among boys, although this may be in part reflective of differences in exposure patterns.

Early pregnancy agricultural pesticide exposures and risk of gastroschisis among offspring in the San Joaquin Valley of California.

BACKGROUND: Prevalence of gastroschisis has inexplicably been increasing over the past few decades. Our intent was to explore whether early gestational exposures to pesticides were associated with risk of gastroschisis. METHODS: We used population-based data, accompanied by detailed information from maternal interviews as well as information on residential proximity to a large number of commercial pesticide applications during early pregnancy. The study population derived from the San Joaquin Valley of California (). Cases were 156 infants/fetuses with gastroschisis and controls were 785 infants without birth defects. RESULTS: Among 22 chemical pesticide groups analyzed, none had an elevated odds ratio with an associated confidence interval that excluded 1.0, although exposure to the triazine group showed borderline significance. Among 36 specific pesticide chemicals analyzed, only exposure to petroleum distillates was associated with an elevated risk, odds ratio = 2.5 (1.1-5.6). In general, a substantially different inference was not derived when analyses were stratified by maternal age or when risk estimation included adjustment for race/ethnicity, body mass index, folic acid supplement use, and smoking. CONCLUSION: Our study rigorously adds to the scant literature on this topic. Our a priori expectation was that we would observe certain pesticide compounds to be particularly associated with young age owing to the disproportionate risk observed for young women to have offspring with gastroschisis. We did not observe an exposure profile unique to young women.

Association of intrauterine and early life factors with uterine leiomyomata in black women.

PURPOSE: Uterine leiomyomata (UL) are the primary indication for hysterectomy and are 2-3 times more common in black than white women. Previous studies indicate that early life may be a critical time window of susceptibility to UL. We assessed the association of UL with selected intrauterine and early life factors, expanding on previous research by using a prospective design and validated data on exposure and disease. METHODS: During 1997-2009, we followed 23,505 premenopausal women aged 23-50 years for new diagnoses of UL in the Black Women's Health Study. We used Cox regression models to compute incidence rate ratios (IRR) and 95% confidence intervals, adjusting for potential confounders. RESULTS: During 12 years of follow-up, there were 7268 incident UL cases diagnosed by ultrasound (n = 5727) or surgery (n = 1541). There was little evidence of an association between UL and birth weight, gestational age, or exposure to soy formula in infancy. Significant associations were found for being first born, foreign born, or exposed to passive smoke in childhood, but the associations were weak, with IRRs ranging from 1.06 to 1.12. CONCLUSIONS: These findings do not support the hypothesis that intrauterine and early life factors are strongly related to UL risk.

Effects of maternal 5,10-methylenetetrahydrofolate reductase C677T and A1298C Polymorphisms and tobacco smoking on infant birth weight in a Japanese population.

BACKGROUND: Intracellular folate hemostasis depends on the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. Because 5,10-MTHFR 677TT homozygosity and tobacco smoking are associated with low folate status, we tested the hypothesis that smoking in mothers with 5,10-MTHFR C677T or A1298C polymorphisms would be independently associated with lower birth weight among their offspring. METHODS: We assessed 1784 native Japanese mother-child pairs drawn from the ongoing birth cohort of The Hokkaido Study on Environment and Children's Health. Data (demographic information, hospital birth records, and biological specimens) were extracted from recruitments that took place during the period from February 2003 to March 2006. Maternal serum folate were assayed by chemiluminescent immunoassay, and genotyping of 5,10-MTHFR C677T/A1298C polymorphisms was done using a TaqMan allelic discrimination assay. RESULTS: The prevalence of folate deficiency (<6.8 nmol/L) was 0.3%. The 5,10-MTHFR 677CT genotype was independently associated with an increase of 36.40 g (95% CI: 2.60 to 70.30, P = 0.035) in mean infant birth weight and an increase of 90.70 g (95% CI: 6.00 to 175.50, P = 0.036) among male infants of nonsmokers. Female infants of 677TT homozygous passive smokers were 99.00 g (95% CI: -190.26 to -7.56, P = 0.034) lighter. The birth weight of the offspring of smokers with 5,10-MTHFR 1298AA homozygosity was lower by 107.00 g (95% CI: -180.00 to -33.90, P = 0.004). CONCLUSIONS: The results suggest that, in this population, maternal 5,10-MTHFR C677T polymorphism, but not the 5,10-MTHFR A1298C variant, is independently associated with improvement in infant birth weight, especially among nonsmokers. However, 5,10-MTHFR 1298AA might be associated with folate impairment and could interact with tobacco smoke to further decrease birth weight.

Early-life exposures and early-onset uterine leiomyomata in black women in the Sister Study.

BACKGROUND: Uterine leiomyomata (fibroids) are hormonally responsive tumors, but little is known about risk factors. Early-life exposures may influence uterine development and subsequent response to hormones in adulthood. An earlier analysis of non-Hispanic white women who participated in the Sister Study found associations between several early-life factors and early-onset fibroids. OBJECTIVES: We evaluated associations of early-life and childhood exposures with early-onset fibroids among black women and compared the results with those found among white women. METHODS: We analyzed baseline data from 3,534 black women, 35-59 years of age, in the Sister Study (a nationwide cohort of women who had a sister diagnosed with breast cancer) who self-reported information on early-life and childhood exposures. Early-onset fibroids were assessed based on self-report of a physician diagnosis of fibroids by the age of 30 years (n = 561). We estimated risk ratios (RR) and 95% confidence intervals (CI) from log-binomial regression models. RESULTS: Factors most strongly associated with early-onset fibroids were in utero diethylstilbestrol (DES; RR = 2.02; 95% CI: 1.28, 3.18), maternal prepregnancy diabetes or gestational diabetes (RR = 1.54; 95% CI: 0.95, 2.49), and monozygotic multiple birth (RR = 1.94; 95% CI: 1.26, 2.99). We also found positive associations with having been taller or thinner than peers at the age of 10 years and with early-life factors that included being the firstborn child of a teenage mother, maternal hypertensive disorder, preterm birth, and having been fed soy formula. CONCLUSIONS: With the exception of monozygotic multiple birth and maternal hypertensive disorder, early-life risk factors for early-onset fibroids for black women were similar to those found for white women. However, in contrast to whites, childhood height and weight, but not low socioeconomic status indicators, were associated with early-onset fibroids in blacks. The general consistency of early-life findings for black and white women supports a possible role of early-life factors in fibroid development.

Alcohol, smoking, and drug use among Inuit women of childbearing age during pregnancy and the risk to children.

BACKGROUND: Alcohol consumption during pregnancy, a known teratogen often associated with drug use and smoking is a well-known public health concern. AIM: This study provides prevalence data for alcohol, smoking, and illicit drug use before, during, and after pregnancy among Inuit. Factors associated with alcohol use are also identified. METHODS: Two hundred and eight Inuit women from Arctic Quebec were interviewed at mid-pregnancy, and at 1 and 11 months postpartum to provide descriptive data on smoking, alcohol, and drug use during pregnancy, and the year before and after pregnancy. Sociodemographic and family characteristics potentially associated with alcohol use were documented. RESULTS: Ninety-two percent of the women reported smoking and 61% reported drinking during pregnancy. Episodes of binging during pregnancy were reported by 62% of the alcohol users, which correspond to 38% of pregnant women. Thirty-six percent of the participants reported using marijuana during pregnancy. Alcohol use and binge drinking during pregnancy were more likely to be reported by women who lived in less crowded houses, had a better knowledge of a second language, drank alcohol more often and in larger amounts prior to pregnancy, and used illicit drugs. Binge drinkers were more likely to be single women and to have had fewer previous pregnancies. Postpartum distress and violence were more likely to be experienced by women who used alcohol during pregnancy. Binge drinking during pregnancy was best predicted by drinking habits before pregnancy, maternal symptoms of depression, the use of illicit drugs during pregnancy, and the number of young children living with the mother. CONCLUSIONS: These results confirm that alcohol is a major risk factor to maternal and child health in this population, underscoring the need for culturally relevant and effective prevention programs.

Life course socioeconomic conditions, passive tobacco exposures and cigarette smoking in a multiethnic birth cohort of U.S. women.

Low socioeconomic status (SES) and exposure to passive tobacco smoke are associated with increased risk of smoking in adults, but the influences of these factors in earlier life periods on adult smoking behavior are not well understood. We investigated the relationship of SES and passive tobacco exposure over the lifecourse with adult smoking status in a multiethnic cohort of U.S. women (n = 262, average age = 41.8), using prospective data on maternal smoking during pregnancy and childhood SES, and follow-up data on current smoking, adult SES and household tobacco exposure. Low adolescent and adult SES consistently increased the risk of current smoking, but most associations were not statistically significant in multivariable models. Blue collar parental occupation at birth increased the risk of smoking, particularly for current smoking relative to former smoking (odds ratio [OR] = 2.7, 95% confidence interval [CI] = 1.2-5.9). After adjusting for SES, current and former smokers were more likely than never smokers to have exposures to prenatal tobacco (OR = 4.4, 95% CI = 2.1-9.4 and OR = 2.0, 95% CI = 1.0-4.2, respectively) and adult household tobacco (OR = 2.7, 95% CI = 1.3-5.8 and OR = 2.4, 95% CI = 1.2-4.8, respectively). Our results show that early life conditions have enduring influences on women's smoking behavior in middle adulthood, even after considering similar types of conditions in later life periods.

The effect of maternal smoking and drinking during pregnancy upon (3)H-nicotine receptor brainstem binding in infants dying of the sudden infant death syndrome: initial observations in a high risk population.

The high rate of the sudden infant death syndrome (SIDS) in American Indians in the Northern Plains (3.5/1000) may reflect the high incidence of cigarette smoking and alcohol consumption during pregnancy. Nicotine, a neurotoxic component of cigarettes, and alcohol adversely affect nicotinic receptor binding and subsequent cholinergic development in animals. We measured (3)H-nicotine receptor binding in 16 brainstem nuclei in American Indian SIDS (n = 27) and controls (n = 6). In five nuclei related to cardiorespiratory control, (3)H-nicotinic binding decreased with increasing number of drinks (P < 0.03). There were no differences in binding in SIDS compared with controls, except upon stratification of prenatal exposures. In three mesopontine nuclei critical for arousal there were reductions (P < 0.04) in binding in controls exposed to cigarette smoke compared with controls without exposure; there was no difference between SIDS cases with or without exposure. This study suggests that maternal smoking and alcohol affects (3)H-nicotinic binding in the infant brainstem irrespective of the cause of death. It also suggests that SIDS cases are unable to respond to maternal smoking with the "normal" reduction seen in controls. Future studies are needed to establish the role of adverse prenatal exposures in altered brainstem neurochemistry in SIDS.

Neighborhood economic disadvantage, violent crime, group density, and pregnancy outcomes in a diverse, urban population.

Prior research has established associations between pregnancy outcomes and specific neighborhood characteristics, including economic disadvantage, violent crime, and racial/ethnic segregation. Recently, associations have also been found between various health outcomes and group density, the degree to which an individual is a racial or ethnic majority in his or her local community. The objective of this study was to determine the extent to which census tract economic disadvantage, violent crime rate, and group density are associated with pregnancy outcomes among White, Black, and Hispanic infants in a large metropolitan setting. This cross-sectional study utilized 1990 census data, 1991 crime data, and 1991 birth certificate information for singleton live births in Chicago, Illinois. Results show substantial racial segregation in Chicago, with 35% of census tracts having more than 90% Black residents and 45% of census tracts having fewer than 10% Black residents. After stratifying by maternal race/ethnicity, we used multilevel analyses to model pregnancy outcomes as a function of individual and census tract characteristics. Among all racial/ethnic groups, violent crime rate accounted for most of the negative association between tract economic disadvantage and birth weight. Group density was also associated with birth weight but this association was stronger among Whites and Hispanics than among Blacks. Further analysis revealed that group density was more strongly associated with preterm birth while violent crime rate was more strongly associated with small for gestational age. These results suggest that group density and violent crime may impact birth weight via different mechanisms.