The paradox of high greenness and poor health in rural Central Appalachia.

While many studies have found positive correlations between greenness and human health, rural Central Appalachia is an exception. The region has high greenness levels but poor health. The purpose of this commentary is to provide a possible explanation for this paradox: three sets of factors overwhelming or attenuating the health benefits of greenness. These include environmental (e.g., steep typography and limited access to green space used for outdoor recreation), social (e.g., chronic poverty, declining coal industry, and limited access to healthcare), and psychological and behavioral factors (e.g., perceptions about health behaviors, healthcare, and greenness). The influence of these factors on the expected health benefits of greenness should be considered as working hypotheses for future research. Policymakers and public health officials need to ensure that greenness-based interventions account for contextual factors and other determinants of health to ensure these interventions have the expected health benefits.

Immediate complications and flow volume changes during treatment phases of bronchial thermoplasty: a single-center descriptive study.

INTRODUCTION: Bronchial thermoplasty (B.T.) is a therapeutic bronchoscopic procedure in which controlled thermal energy is applied to the airway wall to decrease smooth muscle mass. Immediate complications of B.T. include acute exacerbation of bronchial asthma, upper and lower respiratory tract infection, hemoptysis, among others. Our study assessed these immediate adverse events and the changes in forced expiratory volume in one second (FEV1%) measured four hours after each procedure from baseline. The study also aimed to examine the number of activations during each cycle of treatment and its correlation to the corresponding change in FEV1% from baseline. METHODS: A case-series analysis of 17 patients who underwent B.T. between 2014 and 2019 was done. Demographic, clinical characteristics, including pre and post-BT FEV1% measures, and the number of activations were obtained. RESULTS: Acute exacerbation of asthma was the commonest complication accounting for 33%, 57%, and 75% after BT1, BT2, and BT3, respectively. There was deterioration in FEV1% after each treatment phase, the most significant being in BT3. There was no correlation between the number of heat activations with the change in FEV1% from baseline. CONCLUSION: The number of activations in B.T. does not correlate with the immediate deterioration in FEV1%, although exacerbation of asthma is the commonest complication post-B.T.

In utero exposure to atrazine analytes and early menarche in the Avon Longitudinal Study of Parents and Children Cohort.

BACKGROUND: Evidence from experimental studies suggests that atrazine and its analytes alter the timing of puberty in laboratory animals. Such associations have not been investigated in humans. OBJECTIVE: To determine the association between in utero exposure to atrazine analytes and earlier menarche attainment in a nested case-control study of the population-based Avon Longitudinal Study of Parents and Children. METHODS: Cases were girls who reported menarche before 11.5 years while controls were girls who reported menarche at or after 11.5 years. Seven atrazine analyte concentrations were measured in maternal gestational urine samples (sample gestation week median (IQR): 12 (8-17)) during the period 1991-1992, for 174 cases and 195 controls using high performance liquid chromatography-tandem mass spectrometry. We evaluated the study association using multivariate logistic regression, adjusting for potential confounders. We used multiple imputation to impute missing confounder data for 29% of the study participants. RESULTS: Diaminochlorotriazine (DACT) was the most frequently detected analyte (58%>limit of detection [LOD]) followed by desethyl atrazine (6%), desethyl atrazine mercapturate (3%), atrazine mercapturate (1%), hydroxyl atrazine (1%), atrazine (1%) and desisopropyl atrazine (0.5%). Because of low detection of other analytes, only DACT was included in the exposure-outcome analyses. The adjusted odds of early menarche for girls with DACT exposures≥median was 1.13 (95% Confidence Interval [95% CI]:0.82, 1.55) and exposure

Associations of lifestyle factors (smoking, alcohol consumption, diet and physical activity) with type 2 diabetes among American adults from National Health and Nutrition Examination Survey (NHANES) 2005-2014.

BACKGROUND: Over the long term, unhealthy lifestyles can lead to many health problems, especially type 2 diabetes (T2D). The aim of the present study was to determine associations between lifestyle factors (smoking, alcohol consumption, physical activity, and diet) and T2D in American adults (aged ≥20 years) in a nationally representative sample. METHODS: Data for 12 987 American adults participating in the National Health and Nutrition Examination Survey 2005-2014 were evaluated. Weighted multiple logistic regression models were used to examine associations between the four lifestyle factors and T2D after adjusting for demographics and socioeconomic status (SES). Prevalence trends for T2D were examined using Cochran-Armitage tests. RESULTS: There was a significant increasing prevalence trend for T2D among American adults. Smokers and individuals consuming >12 alcoholic drinks in the past year were less likely to report having T2D than non-smokers (odds ratio [OR] 0.41; 95% confidence interval [CI] 0.35-0.48) and those consuming <12 alcoholic drinks (OR 0.46; 95% CI 0.39-0.55). Participants with light physical activity have a greater likelihood of having T2D than those engaging in vigorous physical activity (OR 5.72; 95% CI 4.30-7.60). Individuals consuming a poor diet were more likely to report having T2D than those eating an excellent diet (OR 1.18; 95% CI 1.02-1.41). All these relationships remained significant after adjustment for demographics and SES. CONCLUSION: All four lifestyle factors were significantly associated with T2D among American adults. The findings of the present study provide useful information for healthcare providers that may help them promote specific lifestyle modifications.

In utero exposure to organochlorine pesticides and early menarche in the Avon Longitudinal Study of Parents and Children.

INTRODUCTION: Epidemiologic data supporting the role of organochlorine pesticides in pubertal development are limited. METHODS: Using a nested case-control design, serum collected during pregnancy from mothers of 218 girls who reported menarche before 11.5years of age (cases) and 230 girls who reported menarche at or after 11.5years of age (controls) was analyzed for 9 organochlorines and metabolites. We analyzed the association between in utero organochlorine concentrations and early menarche using multivariate logistic regression controlling for mother's age at menarche, or mother's prenatal BMI. RESULTS: We did not observe an association between in utero exposure to HCB, ß-HCH, ϒ-HCH, p,p'-DDT, p,p'-DDE, oxychlordane or trans-nonachlor and early menarche. CONCLUSIONS: This study is the first to examine the association between in utero exposure to HCB, ß-HCH, ϒ-HCH, oxychlordane or trans-nonachlor and early menarche. In utero exposure to organochlorine pesticides does not appear to have a role in the timing of menarche in this study.

Prenatal Exposure to Perfluoroalkyl Acids and Serum Testosterone Concentrations at 15 Years of Age in Female ALSPAC Study Participants.

BACKGROUND: Exposure to perfluorooctane sulfonic acid (PFOS) or to perfluorooctanoic acid (PFOA) increases mouse and human peroxisome proliferator-activated receptor alpha (PPARα) subtype activity, which influences lipid metabolism. Because cholesterol is the substrate from which testosterone is synthesized, exposure to these substances has the potential to alter testosterone concentrations. OBJECTIVES: We explored associations of total testosterone and sex hormone-binding globulin (SHBG) concentrations at age 15 years with prenatal exposures to PFOS, PFOA, perfluorohexane sulfonic acid (PFHxS), and perfluoronanoic acid (PFNA) in females. METHODS: Prenatal concentrations of the perfluoroalkyl acids (PFAAs) were measured in serum collected from pregnant mothers at enrollment (1991-1992) in the Avon Longitudinal Study of Parents and Children (ALSPAC). The median gestational age when the maternal blood sample was obtained was 16 weeks (interquartile range, 11-28 weeks). Total testosterone and SHBG concentrations were measured in serum obtained from their daughters at 15 years of age. Associations between prenatal PFAAs concentrations and reproductive outcomes were estimated using linear regression models (n = 72). RESULTS: Adjusted total testosterone concentrations were on average 0.18-nmol/L (95% CI: 0.01, 0.35) higher in daughters with prenatal PFOS in the upper concentration tertile compared with daughters with prenatal PFOS in the lower tertile. Adjusted total testosterone concentrations were also higher in daughters with prenatal concentrations of PFOA (ß = 0.24; 95% CI: 0.05, 0.43) and PFHxS (ß = 0.18; 95% CI: 0.00, 0.35) in the upper tertile compared with daughters with concentrations in the lower tertile. We did not find evidence of associations between PFNA and total testosterone or between any of the PFAAs and SHBG. CONCLUSIONS: Our findings were based on a small study sample and should be interpreted with caution. However, they suggest that prenatal exposure to some PFAAs may alter testosterone concentrations in females.

Prenatal exposures to perfluoroalkyl acids and serum lipids at ages 7 and 15 in females.

BACKGROUND: In some cross-sectional epidemiologic studies the shape of the association between serum concentrations of perfluoroalkyl acids (PFAAs) and lipids suggests departures from linearity. OBJECTIVES: We used statistical approaches allowing for non-linearity to determine associations of prenatal exposures of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) with lipid concentrations. METHODS: PFAAs were measured in serum from pregnant women collected in 1991-1992 at enrollment in the Avon Longitudinal Study of Parents and Children and lipids in serum from their daughters at ages 7 (n=111) and 15 (n=88). The associations of PFAAs with lipids were first explored by cubic splines, followed by piecewise linear regressions by tertiles to obtain regression coefficients (ß) and their 95% confidence limits (95% CL) (in mg/dL per 1ng/mL). RESULTS: At age 7, total cholesterol was positively associated with prenatal PFOA concentrations in the lower tertile (ß=15.01; 95% CL=2.34, 27.69) but not with PFOA concentrations in the middle (ß=-3.63; 95% CL=-17.43, 10.16) and upper (ß=-1.58; 95% CL=-4.58, 1.42) tertiles. At age 15, a similar pattern was noted as well. Positive associations between LDL-C and prenatal PFOA concentration in the lower tertile were observed in daughters at ages 7 (ß=14.91; 95% CL=3.53, 28.12) and 15 (ß=13.93; 95% CL=0.60, 27.26). LDL-C was not associated with PFOA concentrations in the middle or upper tertile at any age. Neither HDL-C nor triglycerides was associated with prenatal PFOA exposure. Non-linear patterns of association of total cholesterol and LDL-C with prenatal PFOS were less consistently noted. CONCLUSION: Exposure to low levels of PFOA during prenatal development may alter lipid metabolism later in life. Given the small sample size further replication of the association in large independent cohorts is important.

Associations of Perfluoroalkyl Substances (PFAS) with Lower Birth Weight: An Evaluation of Potential Confounding by Glomerular Filtration Rate Using a Physiologically Based Pharmacokinetic Model (PBPK).

BACKGROUND: Prenatal exposure to perfluoroalkyl substances (PFAS) has been associated with lower birth weight in epidemiologic studies. This association could be attributable to glomerular filtration rate (GFR), which is related to PFAS concentration and birth weight. OBJECTIVES: We used a physiologically based pharmacokinetic (PBPK) model of pregnancy to assess how much of the PFAS-birth weight association observed in epidemiologic studies might be attributable to GFR. METHODS: We modified a PBPK model to reflect the association of GFR with birth weight (estimated from three studies of GFR and birth weight) and used it to simulate PFAS concentrations in maternal and cord plasma. The model was run 250,000 times, with variation in parameters, to simulate a population. Simulated data were analyzed to evaluate the association between PFAS levels and birth weight due to GFR. We compared simulated estimates with those from a meta-analysis of epidemiologic data. RESULTS: The reduction in birth weight for each 1-ng/mL increase in simulated cord plasma for perfluorooctane sulfonate (PFOS) was 2.72 g (95% CI: -3.40, -2.04), and for perfluorooctanoic acid (PFOA) was 7.13 g (95% CI: -8.46, -5.80); results based on maternal plasma at term were similar. Results were sensitive to variations in PFAS level distributions and the strength of the GFR-birth weight association. In comparison, our meta-analysis of epidemiologic studies suggested that each 1-ng/mL increase in prenatal PFOS and PFOA levels was associated with 5.00 g (95% CI: -21.66, -7.78) and 14.72 g (95% CI: -8.92, -1.09) reductions in birth weight, respectively. CONCLUSION: Results of our simulations suggest that a substantial proportion of the association between prenatal PFAS and birth weight may be attributable to confounding by GFR and that confounding by GFR may be more important in studies with sample collection later in pregnancy.

Maternal concentrations of polyfluoroalkyl compounds during pregnancy and fetal and postnatal growth in British girls.

BACKGROUND: Prenatal exposures to polyfluoroalkyl compounds (PFCs) may be associated with adverse changes in fetal and postnatal growth. OBJECTIVE: We explored associations of prenatal serum concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexane sulfonate (PFHxS) with fetal and postnatal growth in girls. METHODS: We studied a sample of 447 singleton girls and their mothers participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). Data on weight and length were obtained at birth and at 2, 9, and 20 months. Serum samples were obtained in 1991-1992, from mothers during pregnancy. We explored associations between prenatal PFC concentrations and weight at birth as well as longitudinal changes in weight-for-age SD scores between birth and 20 months. RESULTS: PFOS (median, 19.6 ng/mL), PFOA (median, 3.7 ng/mL), and PFHxS (median, 1.6 ng/mL) were detected in 100% of samples. On average, girls born to mothers with prenatal concentrations of PFOS in the upper tertile weighed 140 g less [95% confidence interval (CI): -238, -42] at birth than girls born to mothers with concentrations in the lower tertile in adjusted models. Similar patterns were seen for PFOA (-133 g; 95% CI: -237, -30) and PFHxS (-108 g; 95% CI: -206, -10). At 20 months, however, girls born to mothers with prenatal concentrations of PFOS in the upper tertile weighed 580 g more (95% CI: 301, 858) when compared with those in the lower tertile. No differences in weight were found for PFOA and PFHxS. CONCLUSIONS: Girls with higher prenatal exposure to each of the PFCs examined were smaller at birth than those with lower exposure. In addition, those with higher exposure to PFOS were larger at 20 months.

Early-life soy exposure and age at menarche.

This study examines the timing of menarche in relation to infant-feeding methods, specifically addressing the potential effects of soy isoflavone exposure through soy-based infant feeding. Subjects were participants in the Avon Longitudinal Study of Parents and Children (ALSPAC). Mothers were enrolled during pregnancy and their children have been followed prospectively. Early-life feeding regimes, categorised as primarily breast, early formula, early soy and late soy, were defined using infant-feeding questionnaires administered during infancy. For this analysis, age at menarche was assessed using questionnaires administered approximately annually between ages 8 and 14.5. Eligible subjects were limited to term, singleton, White females. We used Kaplan-Meier survival curves and Cox proportional hazards models to assess age at menarche and risk of menarche over the study period. The present analysis included 2920 girls. Approximately 2% of mothers reported that soy products were introduced into the infant diet at or before 4 months of age (early soy). The median age at menarche [interquartile range (IQR)] in the study sample was 153 months [144-163], approximately 12.8 years. The median age at menarche among early soy-fed girls was 149 months (12.4 years) [IQR, 140-159]. Compared with girls fed non-soy-based infant formula or milk (early formula), early soy-fed girls were at 25% higher risk of menarche throughout the course of follow-up (hazard ratio 1.25 [95% confidence interval 0.92, 1.71]). Our results also suggest that girls fed soy products in early infancy may have an increased risk of menarche specifically in early adolescence. These findings may be the observable manifestation of mild endocrine-disrupting effects of soy isoflavone exposure. However, our study is limited by few soy-exposed subjects and is not designed to assess biological mechanisms. Because soy formula use is common in some populations, this subtle association with menarche warrants more in-depth evaluation in future studies.

Exposure to lead from a storage site associated with intellectual impairment in Chilean children living nearby.

This study assesses the degree of impairment of children's IQ scores due to exposure to lead from a storage site. In 2005, we studied 192 children in Antofagasta, Chile, age 7-16 years who had been exposed to a lead storage site from birth until its removal in 1998. We used past (1998) and current (2005) blood lead levels as explanatory variables for IQ, which was measured once in 2005 using the WISC-r test. Multilevel mixed-effects linear regression models were constructed, adjusting for potential confounders. Current blood lead level (BPb, 2005) was associated with a significant decrease in full-scale IQ (P value = 0.03), whereas blood lead level measured in 1998 (BPb, 1998) showed an inverse but not significant association with full-scale IQ (P value = 0.35). The findings provide evidence that exposure to an open source of environmental lead can exert an effect on IQ. Policy efforts should be targeted to prevent lead exposure to avoid children's intellectual impairment.

Timing of maturation and predictors of Tanner stage transitions in boys enrolled in a contemporary British cohort.

This study describes the timing of puberty in 8- to 14-year-old boys enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) and identifies factors associated with earlier achievement of advanced pubic hair stages. Women were enrolled during pregnancy and their offspring were followed prospectively. We analysed self-reported pubic hair Tanner staging collected annually. We used survival models to estimate median age of attainment of pubic hair stage >1, stage >2 and stage >3 of pubic hair development. We also constructed multivariable logistic regression models to identify factors associated with earlier achievement of pubic hair stages. Approximately 5% of the boys reported Tanner pubic hair stage >1 at age 8; 99% of boys were at stage >1 by age 14. The estimated median ages of entry into stages of pubic hair development were 11.4 years [95% confidence interval (CI) 11.3, 11.4] for stage >1, 12.7 years [95% CI 12.7, 12.8] for stage >2 and 13.5 years [95% CI 13.5, 13.6] for stage >3. Predictors of younger age at Tanner stage >1 included low birthweight, younger maternal age at delivery and being taller at age 8. Associations were found between younger age at attainment of stage >2 and gestational diabetes and taller or heavier body size at age 8. Being taller or heavier at age 8 also predicted younger age at Tanner stage >3. The results give added support to the strong influence of pre-adolescent body size on male pubertal development; the tallest and heaviest boys at 8 years achieved each stage earlier and the shortest boys later. Age at attainment of pubic hair Tanner stages in the ALSPAC cohort are similar to ages reported in other European studies that were conducted during overlapping time periods. This cohort will continue to be followed for maturational information until age 17.

Exposure to polyfluoroalkyl chemicals during pregnancy is not associated with offspring age at menarche in a contemporary British cohort.

INTRODUCTION: Polyfluoroalkyl chemicals (PFCs) are commercially synthesized chemicals used in consumer products. Exposure to certain PFCs is widespread, and some PFCs may act as endocrine disruptors. We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) in the United Kingdom to conduct a nested case-control study examining the association between age at menarche, and exposure to PFCs during pregnancy. METHODS: Cases were selected from female offspring in the ALSPAC who reported menarche before the age of 11.5 years (n = 218), and controls were a random sample of remaining girls (n = 230). Serum samples taken from the girls' mothers during pregnancy (1991-1992) were analyzed using on-line solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry for 8 PFCs. Logistic regression was used to determine association between maternal serum PFC concentrations, and odds of earlier age at menarche. RESULTS: PFOS and PFOA were the predominant PFCs (median serum concentrations of 19.8 ng/mL and 3.7 ng/mL). All but one PFC were detectable in most samples. Total PFC concentration varied by number of births (inverse association with birth order; p-value < 0.0001) and race of the child (higher among whites; p-value = 0.03). The serum concentrations of carboxylates were associated with increased odds of earlier age at menarche; concentrations of perfluorooctane sulfonamide, the sulfonamide esters and sulfonates were all associated with decreased odds of earlier age at menarche. However, all confidence intervals included the null value of 1.0. CONCLUSIONS: ALSPAC study participants had nearly ubiquitous exposure to most PFCs examined, but PFC exposure did not appear to be associated with altered age at menarche of their offspring.

Role of prenatal characteristics and early growth on pubertal attainment of British girls.

OBJECTIVES: The objective of this study was to explore the influence of maternal prenatal characteristics and behaviors and of weight and BMI gain during early childhood on the timing of various puberty outcomes in girls who were enrolled in the Avon Longitudinal Study of Parents and Children. METHODS: Repeated self-assessments of pubertal development were obtained from approximately 4000 girls between the ages of 8 and 14. Data on prenatal characteristics and weight at birth and 2, 9, and 20 months of age were obtained from questionnaires, birth records, and clinic visits. Infants' weights were converted to weight-for-age and BMI SD scores (SDSs; z scores), and change values were obtained for the 0- to 20-month and other intervals within that age range. We used parametric survival models to estimate associations with age of entry into Tanner stages of breast and pubic hair and menarche. RESULTS: Maternal initiation of menarche at age<12, smoking during pregnancy, and primiparity were associated with earlier puberty. A 1-unit increase in the weight SDS change values for the 0- to 20-month age interval was associated with earlier ages of entry into pubertal outcomes (0.19-0.31 years). Increases in the BMI SDS change values were also associated with earlier entry into pubertal outcomes (0.07-0.11 years). CONCLUSIONS: Many of the maternal prenatal characteristics and weight and BMI gain during infancy seemed to have similar influences across different puberty outcomes. Either such early factors have comparable influences on each of the hormonal processes involved in puberty, or processes are linked and awakening of 1 aspect triggers the others.

Progression through puberty in girls enrolled in a contemporary British cohort.

PURPOSE: Patterns of pubertal development reflect underlying endocrine function and exposures, and could affect future health outcomes. We used data from a longitudinal cohort to describe factors associated with breast and pubic hair stage and estimate average duration of puberty. METHODS: Data from the Avon Longitudinal Study of Parents and Children were used to describe timing and duration of pubertal development in girls. Self-reported Tanner stage of breast and pubic hair and menarche status were collected from ages 8-14 through mailed questionnaires. Factors associated with breast and pubic hair stage were identified using ordinal probit models. Age at entry into breast and pubic hair stages, and duration of puberty were estimated using interval-censored parametric survival analysis. RESULTS: Among the 3,938 participants, being overweight or obese, of non-white race, being the firstborn, and younger maternal age at menarche were associated with more advanced breast and pubic hair stages. Having an overweight or obese mother was associated with more advanced breast stages. Time spent in breast stages 2 and 3 was longer (1.5 years) than time spent in pubic hair stages 2 and 3 (1 year). The average age at menarche was 12.9 (95% CI, 12.8-12.9) years, and average duration of puberty (time from initiation of puberty to menarche) was 2.7 years. CONCLUSIONS: Girls in Avon Longitudinal Study of Parents and Children had a slightly longer duration of puberty compared to an earlier British cohort study. Various maternal and child characteristics were associated with breast and pubic hair stage, including both child and maternal body mass.

Pubertal pathways in girls enrolled in a contemporary british cohort.

Data from the Avon Longitudinal Study of Parents and Children were used to describe initiation of secondary sexual characteristic development of girls. Tanner stages of breast and pubic hair and menarche status were self-reported via mailed questionnaires, administered from ages 8-14. Initiation pathway was categorized as breast [thelarche] or pubic hair [pubarche] development alone, or synchronous. Average ages at beginning breast and pubic hair development were estimated using survival analysis. Factors associated with initiation pathway were assessed using logistic regression. Among the 3938 participants, the median ages at beginning breast and pubic hair development were 10.19 (95% CI: 10.14-10.24) and 10.95 (95% CI: 10.90-11.00) years. Synchronous initiation was the most commonly reported pathway (46.3%), followed by thelarche (42.1%). Girls in the pubarche pathway were less likely to be obese or overweight at age 8 or have an overweight or obese mother. Girls in the thelarche pathway were less likely to be of nonwhite race or be the third born or later child.

Characterization of the correlation between ages at entry into breast and pubic hair development.

PURPOSE: The timing of breast and pubic hair development in girls are related, but the degree of correlation has not been well characterized. Periodic observations also are complicated by interval censoring. METHODS: Data used were from the Avon Longitudinal Study of Parents and Children. Mean age at entry into breast and pubic hair development was determined by the use of parametric survival analysis. The bivariate normal cumulative distribution function was evaluated over the region containing the paired event times; the likelihood was maximized with respect to the correlation coefficient rho. RESULTS: Among 3938 participants, estimated mean ages at entry into Tanner stage 2 for breast and pubic hair development were 10.19 and 10.95, respectively. The likelihood was maximized at rho = 0.503 to 0.506. This value remained relatively constant among subgroups, although some heterogeneity was observed by maternal and child body mass index and birth order. CONCLUSIONS: The timing of breast and of pubic hair development is moderately correlated and remain so when it is stratified by characteristics associated with puberty.

Timing of maturation and predictors of menarche in girls enrolled in a contemporary British cohort.

This study describes the timing of puberty in 8- to 13-year-old girls enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) and identifies factors associated with earlier achievement of menarche. Women were enrolled during pregnancy and their offspring were followed prospectively. We analysed self-reported Tanner staging and menstrual status information collected annually from daughters up to age 13. We used survival models to estimate median age of attainment of stage >1 and stage >2 of breast and pubic hair development and of menarche. We also constructed multivariable logistic regression models to identify factors associated with earlier achievement of menarche. About 12% of girls reported Tanner breast stage >1 at age 8; 98% of girls were above stage 1 by age 13. For pubic hair, 5% and 95% of girls had attained a stage >1 by 8 and 13 years, respectively. The estimated median age of entry into stage >1 of breast development was 10.14 years (95% confidence interval [CI], 10.08, 10.19), and for pubic hair development the median age was 10.92 years [95% CI, 10.87, 10.97]. One girl (out of 2953) had attained menarche by age 8; 60% had attained menarche by age 13. The estimated median age at menarche was 12.93 years [95% CI, 12.89, 12.98]. Prenatal predictors of menarche by age 11 (12% of girls) included earlier maternal age at menarche, high maternal pre-pregnancy body mass index, smoking during the third trimester, and non-white race; the single postnatal predictor was the girl's body size at 8 years. Age at attainment of breast and pubic hair Tanner stage and age at menarche in the ALSPAC cohort are similar to ages reported in other European studies that were conducted during overlapping time periods. The results also give added support to the strong influence of maternal maturation, pre-adolescent body size and race on the timing of a girl's menarche. This cohort will continue to be followed for maturational information until age 17.

A review of the literature on the effects of ambient air pollution on fetal growth.

A systematic review of the literature on the effects of air pollution on low birth weight (LBW) and its determinants, preterm delivery (PTD) and intrauterine growth restriction (IUGR), was conducted. Twelve epidemiologic investigations that addressed the impact of air pollution on four pregnancy outcomes were identified. Results were analyzed separately for each perinatal outcome because of differences in pathogenic mechanisms. Effects of air pollution were apparent on PTD and IUGR, but not on LBW. Most of the associations reported were rather small. The estimation of summary effects was not meaningful because of the heterogeneity of the effect estimates arising from differences in the measurements of outcome, exposure, and confounders and the small number of studies per outcome (four studies for PTD and six for IUGR). Current scientific knowledge on the impact of air pollution on fetal growth is still limited; thus, several issues should be examined further.