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To characterize typical menstrual cycle characteristics in adolescents and determine how these differ with age at menarche or years since menarche (gynecologic age). We surveyed 13 to 18-year-old U.S. users of the Clue app (N = 6,486) and linked their responses to app-recorded cycle data (N=38,916 cycles). We analyzed cycle characteristics including cycle length, cycle variability, period length, experience of heavy flow, and dysmenorrhea in relation to gynecologic age and menarcheal age using mixed effects models. With increasing gynecologic age, we observed dose-dependent associations of lower odds of cycle irregularity (defined as cycles that were highly variable, short, or long) and higher odds of reporting ≥1 day of heavy flow. Individuals <1 year post-menarche had lower odds of heavy flow (Odds Ratio (OR) = 0.3; 95% confidence interval (CI): 0.1, 0.6), and increased odds of having a highly variable cycle (OR = 2.6; 95% CI: 1.3, 5.2) or short cycles (OR = 5.0; 95% CI: 2.3, 11.0) compared to those who were 6+ years post-menarche. We also found associations with early and late age at menarche. Compared to menarcheal age of 14+ years, menarcheal age ≤10 years was associated with shorter cycle length (β = -1.63 days; 95% CI: -2.51, -0.75), increased odds of dysmenorrhea (OR = 3.2; 95% CI: 2.3, 4.6), and decreased odds of high cycle variability (OR = 0.8; 95% CI: 0.6, 1.0). Cycle characteristics in adolescence are associated with menarcheal age and gynecologic age. Notably, highly variable cycles are common, especially among those with younger gynecologic age or older menarcheal age. [ABSTRACT FROM AUTHOR]

A quarter of women and nearly 1 in 10 men in the United States have reported experiencing intimate partner violence (IPV) that had lasting negative impacts at least once during their lifetime. To prevent IPV over the lifecourse, adolescence has been identified as an ideal period for healthy relationship education that addresses the various IPV risk factors. One of those risk factors is believing in traditional gender roles, but the behavioral aspect of gender performance has been understudied. This study explores the relationship between adolescent gender performance and adult IPV perpetration and victimization/survival. We used logistic regression to estimate associations of adolescent gender performance and adult IPV perpetration and victimization/survival in a sample of 2,197 males and 2,587 females from The National Longitudinal Study of Adolescent to Adult Health (Add Health) between 1994 and 2008. Male adolescent gender performance was associated with increased adult IPV perpetration (adjusted odds ratio [AOR] = 1.11; 95% confidence interval [CI], 1.05–1.18 per 10% increase in gender performance) and victimization/survival (AOR = 1.07; 95% CI, 1.03–1.11 per 10% increase in gender performance). Female adolescent gender performance was not associated with adult IPV perpetration or victimization/survival. The more similarly adolescent males behave to their adolescent male peers, the more likely they are to perpetrate and experience IPV in adulthood. This study supports the implementation of gender transformative education during adolescence and the specific need to address how the behaviors associated with male gender performance are risk factors for adult IPV. [ABSTRACT FROM AUTHOR]

Objectives: To examine the association of prenatal cannabis use and adverse infant outcomes in a nationally representative cohort and consider the impact of concurrent cigarette exposure.Study Design: We conducted a retrospective cohort study on 32 583 new mothers from the 2017-2019 Pregnancy Risk Assessment Monitoring System. Cannabis use was evaluated as a binary variable (use or no use) as well as ordinal categories (no, light, moderate, heavy use). We used multivariable logistic regression to examine the relationship between prenatal cannabis exposure and low birthweight (LBW), preterm birth, and small for gestational age.Results: Prenatal cannabis use was associated with significantly greater odds of LBW (aOR, 1.27; 95% CI, 1.05-1.54) and small for gestational age (aOR, 1.35; 95% CI, 1.09-1.68) but not preterm birth. Compared with nonusers, heavy users (weekly or more) were twice as likely to deliver a LBW infant (aOR, 2.07; 95% CI, 1.46-2.94) or small for gestational age infant (aOR, 2.14; 95% CI, 1.38-3.30). When examining combined cannabis and cigarette use, prenatal exposure to both substances increased the likelihood of LBW (aOR, 2.27; 95% CI, 1.71-3.01), preterm birth (aOR, 1.61; 95% CI, 1.12-2.31), and small for gestational age (aOR, 3.29; 95% CI, 2.39-4.55) compared with no use, and the increased odds were greater than for either substance alone.Conclusions: Our results suggest that cannabis use during pregnancy may harm fetal development, and recommendations to improve birth outcomes should address co-use of cannabis and tobacco. [ABSTRACT FROM AUTHOR]

Abstract Purpose Research on parental incarceration and the health of offspring is relatively scarce despite studies linking childhood adverse experiences to a range of physical and mental health conditions. This study aimed to estimate the associations between parental incarceration and sexual risk outcomes (early sexual onset, inconsistent condom use, and sexually transmitted infections [STIs]) in young adulthood. Methods We used logistic regression to estimate associations of sexual risk taking behaviors with parental incarceration during childhood in a sample of 3,972 participants in The National Longitudinal Study of Adolescent to Adult Health (Add Health) between 2001 and 2009. Results Parental incarceration was associated with early sexual onset (adjusted odds ratio [AOR] = 1.4, 95% confidence interval [CI] = 1.03–2.03) and STIs (AOR =2.0, 95% CI = 1.3–3.2). Maternal incarceration was associated with increased odds of early sexual onset (AOR = 3.6, 95% CI = 1.9–6.7), inconsistent condom use (AOR = 3.4, 95% CI = 1.3–8.9), and STIs (AOR = 5.5, 95% CI = 1.7–17.6). Additionally, paternal incarceration and parental incarceration occurring before age 10 were associated with STIs (AOR = 1.7, 95% CI = 1.1–2.8; AOR = 2.0, 95% CI = 1.1–3.7). Conclusions Parental incarceration, especially maternal imprisonment, is associated with risky sexual behavior and sexually transmitted infections in young adults in the United States. Intervening during or prior to the adolescent developmental period may ameliorate risky sexual behaviors and related health outcomes among children of incarceration parents. [ABSTRACT FROM AUTHOR]

Background Polybrominated diphenyl ether (PBDE) flame retardants are endocrine-disrupting chemicals that exhibit estrogenic and androgenic properties and may affect pubertal timing. Methods Study subjects were participants between 1999 and 2013 in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal cohort study of predominantly Mexican origin families in Northern California. We measured serum concentrations of four PBDEs (BDE-47, -99, -100, -153) in blood collected from mothers during pregnancy ( N = 263) and their children at age 9 years ( N = 522). We determined timing of pubertal onset in 309 boys and 314 girls using clinical Tanner staging every 9 months between 9 and 13 years of age, and timing of menarche by self-report. We used Poisson regression for relative risk (RR) of earlier puberty and parametric survival analysis for time ratios (TR) of pubertal milestones. Results Prenatal concentrations of all 4 congeners and ƩPBDEs were associated with later menarche in girls (RR earlier menarche = 0.5, 95% confidence interval (CI): 0.3, 0.9 for ƩPBDEs) but earlier pubic hair development in boys (RR earlier pubarche = 2.0, 95% CI: 1.3, 3.3 for ƩPBDEs). No associations were seen between prenatal exposure and girls' breast or pubic hair development or boys' genital development. Childhood PBDE exposure was not associated with any measure of pubertal timing, except for an association of BDE-153 with later menarche. Conclusions We found that prenatal PBDE exposure was associated with later menarche in girls but earlier pubarche in boys, suggesting opposite pubertal effects in girls and boys. [ABSTRACT FROM AUTHOR]

Although banned in most countries, dichlorodiphenyl-trichloroethane (DDT) continues to be used for vector control in some malaria endemic areas. Previous findings from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort study found increased prenatal levels of DDT and its breakdown product dichlorodiphenyl-dichloroethylene (DDE) to be associated with altered neurodevelopment in children at 1 and 2 years of age. In this study, we combined the measured maternal DDT/E concentrations during pregnancy obtained for the prospective birth cohort with predicted prenatal DDT and DDE levels estimated for a retrospective birth cohort. Using generalized estimating equation (GEE) and linear regression models, we evaluated the relationship of prenatal maternal DDT and DDE serum concentrations with children's cognition at ages 7 and 10.5 years as assessed using the Full Scale Intelligence Quotient (IQ) and 4 subtest scores (Working Memory, Perceptual Reasoning, Verbal Comprehension, and Processing Speed) of the Wechsler Intelligence Scale for Children (WISC). In GEE analyses incorporating both age 7 and 10.5 scores (n = 619), we found prenatal DDT and DDE levels were not associated with Full Scale IQ or any of the WISC subscales (p-value > 0.05). In linear regression analyses assessing each time point separately, prenatal DDT levels were inversely associated with Processing Speed at age 7 years (n = 316), but prenatal DDT and DDE levels were not associated with Full Scale IQ or any of the WISC subscales at age 10.5 years (n = 595). We found evidence for effect modification by sex. In girls, but not boys, prenatal DDE levels were inversely associated with Full Scale IQ and Processing Speed at age 7 years. We conclude that prenatal DDT levels may be associated with delayed Processing Speed in children at age 7 years and the relationship between prenatal DDE levels and children's cognitive development may be modified by sex, with girls being more adversely affected. [ABSTRACT FROM AUTHOR]

Objective: To estimate the association between pregnancy glucose values in women without recognized pregestational diabetes or gestational diabetes and cardiometabolic risk in their children. Study design: This longitudinal cohort study of 211 Mexican American mother-child pairs participating in the Center for the Health Assessment of Mothers and Children of Salinas study used multiple logistic regression to estimate the children''s risk of nonfasting total cholesterol, nonfasting triglycerides, blood pressure (BP), and waist circumference (WC) ≥75th percentile at 7 years of age associated with a 1-mmol/L (18-mg/dL) increase in maternal pregnancy glucose level, measured 1 hour after a 50-g oral glucose load. Results: The ORs for children in the upper quartile of diastolic BP, systolic BP, and WC associated with a 1-mmol/L increase in pregnancy glucose level were 1.39 (95% CI, 1.10-1.75), 1.38 (95% CI, 1.10-1.73), and 1.25 (95% CI, 1.02-1.54), respectively. Prepregnancy obesity was independently associated with increased odds of children belonging to the upper quartile of WC; maternal sugar-sweetened beverage consumption and gestational weight gain prior to the glucose test were not independently associated with any of the cardiometabolic outcomes. Conclusion: In Mexican American women without recognized pregestational diabetes or gestational diabetes, we found an association between increasing pregnancy glucose values and the children''s diastolic and systolic BPs and WC at 7 years of age. Whether interventions to reduce pregnancy glucose values, even if below levels diagnostic of overt disease, will mitigate high BP and abdominal obesity in late childhood remains to be determined. [Copyright &y& Elsevier]

Epigenetic marks are key biomarkers linking the prenatal environment to health and development. However, DNA methylation associations and persistence of marks for prenatal exposure to multiple Endocrine Disrupting Chemicals (EDCs) in human populations have not been examined in great detail. We measured Bisphenol-A (BPA), triclosan, benzophenone-3 (BP3), methyl-paraben, propyl-paraben, and butyl-paraben, as well as 11 phthalate metabolites, in two pregnancy urine samples, at approximately 13 and 26 weeks of gestation in participants of the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study (N = 309). DNA methylation of cord blood at birth and child peripheral blood at ages 9 and 14 years was measured with 450K and EPIC arrays. Robust linear regression was used to identify differentially methylated probes (DMPs), and comb-p was used to identify differentially methylated regions (DMRs) in association with pregnancy-averaged EDC concentrations. Quantile g-computation was used to assess associations of the whole phenol/phthalate mixture with DMPs and DMRs. Prenatal BPA exposure was associated with 1 CpG among males and Parabens were associated with 10 CpGs among females at Bonferroni-level significance in cord blood. Other suggestive DMPs (unadjusted p-value < 1 × 10−6) and several DMRs associated with the individual phenols and whole mixture were also identified. A total of 10 CpG sites at least suggestively associated with BPA, Triclosan, BP3, Parabens, and the whole mixture in cord blood were found to persist into adolescence in peripheral blood. We found sex-specific associations between prenatal phenol exposure and DNA methylation, particularly with BPA in males and Parabens in females. Additionally, we found several DMPs that maintained significant associations with prenatal EDC exposures at age 9 and age 14 years. [ABSTRACT FROM AUTHOR]

Background Numerous cross-sectional studies of school-age children have observed that exposure to manganese (Mn) adversely affects neurodevelopment. However, few prospective studies have looked at the effects of both prenatal and postnatal Mn exposure on child neurodevelopment. Methods We measured Mn levels in prenatal and early postnatal dentine of shed teeth and examined their association with behavior, cognition, memory, and motor functioning in 248 children aged 7, 9, and/or 10.5 years living near agricultural fields treated with Mn-containing fungicides in California. We used generalized linear models and generalized additive models to test for linear and nonlinear associations, and generalized estimating equation models to assess longitudinal effects. Results We observed that higher prenatal and early postnatal Mn levels in dentine of deciduous teeth were adversely associated with behavioral outcomes, namely internalizing, externalizing, and hyperactivity problems, in boys and girls at 7 and 10.5 years. In contrast, higher Mn levels in prenatal and postnatal dentine were associated with better memory abilities at ages 9 and 10.5, and better cognitive and motor outcomes at ages 7 and 10.5 years, among boys only. Higher prenatal dentine Mn levels were also associated with poorer visuospatial memory outcomes at 9 years and worse cognitive scores at 7 and 10.5 years in children with higher prenatal lead levels (≥ 0.8 μg/dL). All these associations were linear and were consistent with findings from longitudinal analyses. Conclusions We observed that higher prenatal and early postnatal Mn levels measured in dentine of deciduous teeth, a novel biomarker that provides reliable information on the developmental timing of exposures to Mn, were associated with poorer behavioral outcomes in school-age boys and girls and better motor function, memory, and/or cognitive abilities in school-age boys. Additional research is needed to understand the inconsistencies in the neurodevelopmental findings across studies and the degree to which differences may be associated with different Mn exposure pathways and biomarkers. [ABSTRACT FROM AUTHOR]

Abstract Background Personal care product chemicals may be contributing to risk for asthma and other atopic illnesses. The existing literature is conflicting, and many studies do not control for multiple chemical exposures. Methods We quantified concentrations of three phthalate metabolites, three parabens, and four other phenols in urine collected twice during pregnancy from 392 women. We measured T helper 1 (Th1) and T helper 2 (Th2) cells in their children's blood at ages two, five, and seven, and assessed probable asthma, aeroallergies, eczema, and lung function at age seven. We conducted linear and logistic regressions, controlling for additional biomarkers measured in this population as selected by Bayesian Model Averaging. Results The majority of comparisons showed null associations. Mono- n -butyl phthalate (MnBP) was associated with higher Th2% (RR: 10.40, 95% CI: 3.37, 17.92), and methyl paraben was associated with lower Th1% (RR: −3.35, 95% CI: −6.58, −0.02) and Th2% at borderline significance (RR: −4.45, 95% CI: −8.77, 0.08). Monoethyl phthalate was associated with lower forced expiratory flow from 25 to 75% of forced vital capacity (FEF 25–75%) (RR: −3.22 L/s, 95% CI: −6.02, −0.34). Propyl paraben (OR: 0.86, 95% CI: 0.74, 0.99) was associated with decreased odds of probable asthma. Conclusions While some biomarkers, particularly those from low molecular weight phthalates, were associated with an atopic cytokine profile and poorer lung function, no biomarkers were associated with a corresponding increase in atopic disease. Highlights • LMW phthalates were related to more Th2 producing cells and lower lung function. • No biomarkers were associated with increased odds of asthma, allergies, or eczema. • Methyl paraben was associated with fewer Th1 producing cells. • Bayesian Model Averaging was used to control for multiple chemical exposure. [ABSTRACT FROM AUTHOR]

Flame retardants are commonly used in consumer products found in U.S. households. Restrictions on the use of polybrominated diphenyl ether flame retardants have resulted in increased use of replacement chemicals, including Firemaster 550 ® (FM 550 ® ) and organophosphate flame retardants (PFRs): tris(1,3- dichloro-2-propyl) phosphate (TDCIPP); tris(chloropropyl) phosphate (TCIPP); tris(2-chloroethyl) phosphate (TCEP); and triphenyl phosphate (TPHP). Animal research suggests that PFRs may affect neurodevelopment through noncholinergic mechanisms similar to some organophosphate (OP) pesticides. Despite the widespread presence of these compounds in home environments, and their structural similarity to neurotoxic OP pesticides, understanding of human exposure and health effects of PFRs is limited. We measured four urinary PFR metabolites from pregnant women in the CHAMACOS birth cohort study (n = 310) and assessed neurodevelopment of their children at age 7. Metabolites of TDCIPP (BDCIPP: bis(1,3-dichloro-2-propyl) phosphate) and TPHP (DPHP: diphenyl phosphate) were detected in >75% of urine samples, and isopropylphenyl phenyl phosphate (ip-PPP), a metabolite of one component of FM 550 ® , was detected in 72% of urine samples. We observed decreases of 2.9 points (95% Confidence Interval (CI): −6.3, 0.5) and 3.9 points (95% CI: −7.3,-0.5) in Full-Scale intelligence quotient and Working Memory, respectively, for each ten-fold increase in DPHP in adjusted regression models (n = 248). Decreases in Full-Scale IQ and Working Memory were greater in models of the molar sum of the PFR metabolites compared to the DPHP models. This is the first study to examine PFR and FM 550 ® exposures and potential neurodevelopmental outcomes in pregnant women and children. Additional research is warranted. [ABSTRACT FROM AUTHOR]

Organophosphate flame retardants (PFRs), used in consumer products since the 1970s, persist in the environment. Restrictions on penta-polybrominated diphenyl ether (PBDE) flame retardants resulted in increased use of Firemaster ® 550 (FM ® 550), and the organophosphate triesters: tris(1,3- dichloro-2-propyl) phosphate (TDCIPP); tris(chloropropyl) phosphate (TCIPP); tris(2-chloroethyl) phosphate (TCEP); and triphenyl phosphate (TPHP). The objectives of this study were to (1) identify determinants of flame retardants (4 PFRs, PentaBDEs and FM ® 550) in house dust, (2) measure urinary PFR metabolites in pregnant women, and (3) estimate health risks from PFR exposure. We measured flame retardants in house dust (n = 125) and metabolites in urine (n = 310) collected in 2000–2001 from Mexican American women participating in the CHAMACOS birth cohort study in California. We detected FM ® 550 and PFRs, including two (TCEP and TDCIPP) known to the state of California to cause cancer, in most dust samples. The maximum TCEP and TDCIPP dust levels were among the highest ever reported although the median levels were generally lower compared to other U.S. cohorts. Metabolites of TDCIPP (BDCIPP: bis(1,3-dichloro-2-propyl) phosphate) and TPHP (DPHP: diphenyl phosphate) were detected in 78% and 79% of prenatal urine samples, respectively. We found a weak but positive correlation between TPHP in dust and DPHP in 124 paired prenatal urine samples (Spearman rho = 0.17; p = 0.06). These results provide information on PFR exposure and risk in pregnant women from the early 2000's and are also valuable to assess trends in exposure and risk given changing fire safety regulations and concomitant changes in chemical flame retardant use. [ABSTRACT FROM AUTHOR]

Dichlorodiphenyltrichloroethane (DDT), polybrominated diphenyl ether (PBDE) flame retardants, and polychlorinated biphenyls (PCBs) are believed to be endocrine-disrupting chemicals (EDCs) in humans and animals. The purpose of this study is to examine the relationship of in utero and childhood exposure to these purported EDCs and reproductive hormones in adolescent boys who participated in CHAMACOS, an ongoing birth cohort in California's Salinas Valley. We measured o,p'- and p,p'-DDT, p,p'-DDE, PBDEs and PCBs in serum collected from mothers during pregnancy or at delivery and from their sons at 9 years. We measured concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and total testosterone (T) from 234 of their sons at 12 years. In adjusted models, we found that a 10-fold increase in maternal prenatal serum concentrations of BDE-153 was associated with a 22.2% increase (95% CI: 1.0, 47.9) in FSH, a 96.6% increase (95% CI: 35.7, 184.7) in LH, and a 92.4% increase (95% CI: 20.9, 206.2) increase in T. Similarly, BDE-100 concentrations were associated with increases in boys' LH levels. A 10-fold increase in total prenatal ΣPCBs was associated with a 64.5% increase (95% CI: 8.6, 149.0) in FSH, primarily driven by non- dioxin-like congeners. Boys' hormone levels were only marginally associated with prenatal DDT or DDE in primary models, but when boys' Tanner stage at age 12 was added to models, prenatal maternal DDT levels were associated with decreases in LH (adjusted percent change per 10-fold increase=-18.5%, 95% CI: -29.8, -5.4) and T (percent change=-18.2%, 95% CI: -30.2, -4.2) and DDE with LH (percent change=-18.3%, 95% CI: -32.9, -0.6). Exposures measured in the children's serum at 9 years also showed associations between BDE-153 and ΣPCBs. However, there is evidence that these associations appear to be mediated by child BMI. This study suggests associations on male hormones of 12year old boys related to exposure to certain EDC exposure prenatally. The implications on future reproductive function in puberty and adulthood should be determined. [ABSTRACT FROM AUTHOR]

Objective California children's exposures to polybrominated diphenyl ether flame retardants (PBDEs) are among the highest measured worldwide. We previously reported associations for prenatal and childhood PBDE exposures with decrements in attention, processing speed, fine motor coordination, and cognition in children at ages 5 and 7 years. Here, we investigate associations of PBDEs with attention and executive function at ages 9 to 12 years in the expanded CHAMACOS cohort. Methods We measured PBDEs in prenatal and child age 9 year serum samples for families enrolled in the study since pregnancy (“CHAM1”, N = 321). In a subsequent cohort for which families were enrolled at child age 9 (“CHAM2”, N = 301), we measured PBDEs in maternal and child samples collected at child age 9, and used predictive modeling to estimate prenatal exposure levels. We examined associations of measured and estimated PBDE concentrations on children's attention and executive functioning at ages 9, 10½, and 12 years. Results Geometric means for prenatal and childhood ΣPBDE levels (sum of PBDE-47, -99, -100, -153) for the expanded CHAMACOS cohort were 26.3 and 63.2 ng/g lipid, respectively, and did not differ significantly between CHAM1 and CHAM2 families. We found consistent associations of prenatal exposure to PBDEs with poorer attention and executive function, measured with parent report and direct neuropsychological testing of the child. For example, using GEE models of repeated outcome measures at ages 9 and 12, a 10-fold increase in prenatal ΣPBDE was associated with poorer response consistency on the Conners' Continuous Performance Test II (β = 2.9; 95% CI: 0.9, 4.8) and poorer working memory on the Behavioral Rating Inventory of Executive Function (β = 2.5; 95% CI: 0.5, 4.4). Child age 9 ΣPBDE levels were associated with poorer parent-reported attention and executive function for girls but not boys. Conclusions Our results suggest that the prefrontal cortex may be a potential target for PBDE exposure and add to a growing literature showing that these ubiquitous toxicants may adversely affect neurodevelopment. [ABSTRACT FROM AUTHOR]

• Less developed Mexican-origin pubertal boys at age 14 reported earlier risk taking. • Mexican-origin boys in pubertal transition had high cortisol reactivity to social threat. • High cortisol reactivity predicted early alcohol use initiation in Mexican-origin girls. • High testosterone reactivity predicted early oral sex for Mexican-origin girls. • More pubertally advanced adolescents are at increased risk for earlier risk taking. Latinx adolescents are at a disproportional risk for poor sexual and reproductive health outcomes (STIs, adolescent pregnancy) compared to other ethnic groups. They also report high rates of alcohol and drug use that are similar to non-Hispanic White youth. The hormonal underpinnings of the emergence of sex and substance use behaviors among Latinx adolescents remain understudied however. Pubertal shifts in motivation and reward-seeking in social situations are closely tied to the emergence of risky sexual and substance use behaviors. The experience of developing earlier or later than same age peers may increase stress (cortisol) reactivity during social evaluative situations leading to more risky behavior. Further, testosterone can be responsive to social evaluative threat (SET) and is linked to status-seeking behavior, including risk-taking. The current study sought to unravel the complex relationship between cortisol and testosterone responsivity to social evaluative threat, pubertal status, and the emergence of sex and drug use among US-born Mexican-origin youth growing up in an agricultural community. Mexican American 14-year olds (N = 234, 54% female) from the Center for Health Assessment of Mothers and Children (CHAMACOS) participated in the Trier Social Stress Test. Cortisol and testosterone were assayed from saliva. At 16, youth reported on age at vaginal and oral sex initiation, and alcohol and marijuana use initiation. Hierarchical regressions examined cortisol and testosterone reactivity, and pubertal status within each sex to predict the onset of these risky behaviors. Results indicated that boys who were less developed than their same-aged peers or with lower testosterone reactivity and elevated cortisol reactivity to the TSST reported the earliest sex and substance use initiation. For girls, higher cortisol reactivity predicted earlier alcohol use initiation, and higher testosterone reactivity predicted earlier oral sex. Our results suggests it is important for health care providers to not overlook Latinx boys who may look younger in discussions about mitigating risk. Latinx girls under increased stress may be more likely to try to self-medicate with alcohol, and potentially other drugs. [ABSTRACT FROM AUTHOR]