Urinary cadmium and endometriosis prevalence in a US nationally representative sample: results from NHANES 1999-2006.

STUDY QUESTION: Is exposure to toxic metal cadmium associated with increased endometriosis prevalence among a nationally representative sample of the US population? SUMMARY ANSWER: Concentrations of urinary cadmium, a long-term biomarker (10-30 years) of cadmium exposure, were associated with an increased prevalence of endometriosis. WHAT IS KNOWN ALREADY: Cadmium exhibits estrogenic properties and may increase the risk of endometriosis, a gynecologic condition associated with substantial morbidity, for which estrogen has a central pathogenic role. Previous epidemiological studies of cadmium and endometriosis have yielded mixed results, with null, positive, and inverse associations being reported. STUDY DESIGN, SIZE, DURATION: We conducted a cross-sectional study using data from four cycles of the National Health and Nutrition Examination Survey (NHANES) 1999-2006. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study population comprised participants aged 20-54 years who had an endometriosis diagnosis, available data on urinary cadmium, and a glomerular filtration rate ≥60 ml/min/1.73 m2 (unweighted n = 1647). Urinary cadmium was measured by inductively coupled plasma-mass spectrometry, and we used urinary creatinine concentrations and covariate-adjusted standardization to account for urinary dilution. Self-reported diagnosis of endometriosis was ascertained by interview. We examined the association between quartiles of urinary cadmium and endometriosis using log-binomial regression to estimate adjusted prevalence ratios (aPRs) and 95% CIs. MAIN RESULTS AND THE ROLE OF CHANCE: We observed twice the prevalence of endometriosis for participants with cadmium concentrations in the second quartile (versus the first quartile) (aPR 2.0, 95% CI: 1.1, 3.9) and the third quartile (versus the first quartile) (aPR 2.0, 95% CI: 1.1, 3.7). Our data also suggested a 60% increased prevalence of endometriosis with urinary cadmium concentrations in the fourth quartile (versus the first quartile) (aPR 1.6, 95% CI: 0.8, 3.2). In a sensitivity analysis, restricting the study population to premenopausal participants with an intact uterus and at least one ovary (unweighted n = 1298), stronger associations accompanied by wider CIs were observed. LIMITATIONS, REASONS FOR CAUTION: We were limited by the ascertainment of urinary cadmium and endometriosis diagnosis at a single time point, given the cross-sectional study design, and we relied on self-report of endometriosis diagnosis. However, urinary cadmium characterizes long-term exposure and findings from validation studies suggest that misclassification of self-reported endometriosis diagnosis may be minimal. WIDER IMPLICATIONS OF THE FINDINGS: This study suggests that cadmium is associated with an increased endometriosis prevalence. Given the substantial morbidity conferred by endometriosis and that the general population is ubiquitously exposed to cadmium, further research is warranted to confirm our findings. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Institute of Nursing Research (grant R00NR017191 to K.U.) of the National Institutes of Health. The authors report no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.

Cardiometabolic Pregnancy Complications in Association With Autism-Related Traits as Measured by the Social Responsiveness Scale in ECHO.

Prior work has examined associations between cardiometabolic pregnancy complications and autism spectrum disorder (ASD) but not how these complications may relate to social communication traits more broadly. We addressed this question within the Environmental Influences on Child Health Outcomes program, with 6,778 participants from 40 cohorts conducted from 1998-2021 with information on ASD-related traits via the Social Responsiveness Scale. Four metabolic pregnancy complications were examined individually, and combined, in association with Social Responsiveness Scale scores, using crude and adjusted linear regression as well as quantile regression analyses. We also examined associations stratified by ASD diagnosis, and potential mediation by preterm birth and low birth weight, and modification by child sex and enriched risk of ASD. Increases in ASD-related traits were associated with obesity (ß = 4.64, 95% confidence interval: 3.27, 6.01) and gestational diabetes (ß = 5.21, 95% confidence interval: 2.41, 8.02), specifically, but not with hypertension or preeclampsia. Results among children without ASD were similar to main analyses, but weaker among ASD cases. There was not strong evidence for mediation or modification. Results suggest that common cardiometabolic pregnancy complications may influence child ASD-related traits, not only above a diagnostic threshold relevant to ASD but also across the population.

Click-evoked auditory brainstem responses and autism spectrum disorder: a meta-analytic investigation of disorder specificity.

BACKGROUND: Click-evoked auditory brainstem response (ABR) alterations are associated with autism spectrum disorder (ASD), but the specificity of these findings to the disorder is unclear. We therefore performed a meta-analysis on ABRs and attention-deficit/hyperactivity disorder (ADHD), a neurodevelopmental disorder that shares some etiologic and symptom overlap with ASD. METHODS: Seven papers compared ABR latency components (I, III, V, I-III, III-V, and I-V) between participants with and without ADHD. We used random-effects regression to generate component-specific estimates (Hedges's g) that adjusted for study sample sizes and the number of studies contributing to each estimate. We compared these estimates to our recently published meta-analysis of ABRs and ASD. RESULTS: All ADHD studies employed cross-sectional designs. ADHD was associated with longer latencies for waves III and V (g = 0.6, 95% confidence interval (CI) 0.3, 1.0 and g = 0.6, 95% CI 0.3, 0.9) and waves I-III and I-V (g = 0.7, 95% CI 0.2, 1.3 and g = 0.6, 95% CI 0.3, 1.0). Effect sizes from the ASD and ADHD meta-analyses did not differ from each other. CONCLUSIONS: Similar patterns of ABR alterations are observed in ADHD and ASD. However, studies rarely screen for middle ear dysfunction or hearing loss and rely upon cross-sectional designs. Addressing these issues will inform the viability of ABRs as a prognostic and/or etiologic biomarker for these disorders. IMPACT: Click-evoked ABR alterations are associated with ASD, but the specificity of these findings to the disorder is unclear. We therefore performed a meta-analysis of the association between ABRs and ADHD, a disorder that shares some etiologic and symptom overlap with ASD. ADHD was associated with longer ABR latencies for several components. These components are identical to those implicated in ASD. Effect sizes were similar in magnitude across disorders. The viability of ABRs as prognostic and/or etiologic biomarkers for neurodevelopmental risk requires addressing limitations in the literature (e.g., cross-sectional data, non-standardized ABR protocols, minimal characterization of symptom heterogeneity).

Maternal diet quality moderates associations between parabens and birth outcomes.

BACKGROUND/OBJECTIVE: Maternal paraben exposure and diet quality are both independently associated with birth outcomes, but whether these interact is unknown. We assessed sex-specific associations of parabens with birth outcomes and differences by maternal diet quality. METHODS: Illinois pregnant women (n = 458) provided five first-morning urines collected at 8-40 weeks gestation, which we pooled for quantification of ethylparaben, methylparaben, and propylparaben concentrations. We collected/measured gestational age at delivery, birth weight, body length, and head circumference within 24 h of birth, and calculated sex-specific birth weight-for-gestational-age z-scores and weight/length ratio. Women completed three-month food frequency questionnaires in early and mid-to-late pregnancy, which we used to calculate the Alternative Healthy Eating Index (AHEI)-2010. Linear regression models evaluated sex-specific associations of parabens with birth outcomes, and differences in associations by average pregnancy AHEI-2010. RESULTS: In this predominately non-Hispanic white, college-educated sample, maternal urinary paraben concentrations were only modestly inversely associated with head circumference and gestational length. However, methylparaben and propylparaben were inversely associated with birth weight, birth weight z-scores, body length, and weight/length ratio in female, but not male newborns. For example, each 2-fold increase in methylparaben concentrations was associated with -46.61 g (95% CI: -74.70, -18.51) lower birth weight, -0.09 (95% CI: -0.15, -0.03) lower birth weight z-scores, -0.21 cm (95% CI: -0.34, -0.07) shorter body length, and -0.64 g/cm (95% CI: -1.10, -0.19) smaller weight/length ratio in females. These inverse associations were more prominent in females of mothers with poorer diets (AHEI-2010 < median), but attenuated in those with healthier diets (AHEI-2010 ≥ median). In newborn males of mothers with healthier diets, moderate inverse associations emerged for propylparaben with gestational length and head circumference. CONCLUSIONS: Maternal diet may moderate associations of parabens with birth size in a sex-specific manner. Additional studies may consider understanding the inflammatory and metabolic mechanisms underlying these findings.

Gestational Age at Term, Delivery Circumstance, and Their Association with Childhood Attention Deficit Hyperactivity Disorder Symptoms.

BACKGROUND: Perinatal characteristics may identify subgroups of term-born children at risk for academic and behavioural difficulties. Using follow-up data from the Pregnancy Outcomes and Community Health Study, we subdivided term births according to two potential markers of perinatal risk (gestational age, delivery circumstance) and evaluated their association with attention deficit hyperactivity disorder (ADHD) symptoms. METHODS: We included children born at term whose mothers completed the Conners' Parent Rating Scales-Revised-Short Form (CPRS-R-S) (n = 610; ages: 3-9 years). The CPRS-R-S yields age and sex-referenced T-scores for the two primary dimensions of ADHD (inattention, hyperactivity) and an ADHD Index that reflects both dimensions. Using general linear models, we evaluated whether: (1) term delivery defined by gestational week (reference: 39-40 weeks), or (2) term delivery circumstance defined by labour onset type and mode of delivery (reference: spontaneous labour, vaginal delivery) was associated with these problems. RESULTS: Following adjustment for parity, sociodemographics, and maternal mental health both during pregnancy and at the child follow-up survey, the induced labour plus caesarean group exhibited higher inattention and ADHD Index scores relative to the spontaneous labour, vaginal delivery group (inattention: mean difference = 5.1, 95% CI 0.6, 9.7; ADHD Index: mean difference = 4.1, 95% CI 0.5, 7.8). Findings were primarily driven by male children. CONCLUSIONS: Among term-born children, only those whose mothers experienced induction of labour that culminated in caesarean delivery exhibited higher levels of ADHD symptoms. Prenatal, antepartum, and/or postnatal factors associated with this delivery profile may reflect increased risk for such problems.

The Association Between Adverse Childhood Experiences and Preterm Delivery: A Latent Class Approach.

Background: Racial and socioeconomic status (SES) disparities in preterm delivery (PTD) have existed in the United States for decades. Disproportionate maternal exposures to adverse childhood experiences (ACEs) may increase the risk for adverse birth outcomes. Moreover, racial and SES disparities exist in the prevalence of ACEs, underscoring the need for research that examines whether ACEs contribute to racial and SES disparities in PTD. Methods: We examined the relationship between ACEs and PTD in a longitudinal sample of N = 3,884 women from the National Longitudinal Study of Adolescent to Adult Health (1994-2018). We applied latent class analysis to (1) identify subgroups of women characterized by patterns of ACE occurrence; (2) estimate the association between latent class membership (LCM) and PTD, and (3) examine whether race and SES influence LCM or the association between LCM and PTD. Results: Two latent classes were identified, with women in the high ACEs class characterized by a higher probability of emotional abuse, physical abuse, sexual abuse, and foster care placement compared with the low ACEs class, but neither class was associated with PTD. Race and SES did not predict LCM. Conclusions: Our findings suggest that ACEs may not impact PTD risk in previously hypothesized ways. Future research should assess the impact of ACEs on the probability of having live birth pregnancies as well as the role of potential protective factors in mitigating the impact of ACEs on PTD.

Differences in Psychosocial Protective Factors by Race/Ethnicity and Socioeconomic Status and Their Relationship to Preterm Delivery.

Background: Non-Hispanic Black ("Black") women in the United States deliver preterm at persistently higher rates than non-Hispanic White ("White") women, and disparities in preterm delivery (PTD) also exist by socioeconomic factors. Research is needed to identify and understand factors that are protective against PTD for Black women and low socioeconomic status (SES) women. Methods: We examined seven potential protective factors at the individual, interpersonal, and neighborhood levels during pregnancy to determine if they (1) differed in prevalence by race/ethnicity and SES and (2) were associated with risk of PTD overall or within specific race/ethnicity and SES groups. We used prospectively collected data from n = 2474 women who were enrolled in the Pregnancy Outcomes and Community Health Study conducted in Michigan (1998-2004). Results: White women reported higher levels of self-esteem, mastery, perceived social support, instrumental social support, and reciprocity compared to Black women (all p < 0.01), while Black women reported higher levels of religiosity compared to white women (p < 0.01). High SES women reported higher levels of all protective factors compared to middle and low SES women (all p < 0.01). While protective factors were not independently associated with PTD, religiosity was associated with lower odds of PTD among low SES women (OR 0.6, 95% CI 0.4-0.9) and among Black women (OR 0.6, 95% CI 0.4-1.0), respectively. Conclusions: Our findings highlight the importance of assessing how protective factors may operate differently across race/ethnicity and SES to promote healthy pregnancy outcomes. Future studies should examine mechanisms that elucidate potential causal pathways between religiosity and PTD for Black women and low SES women.

Obstetric oxytocin exposure and ADHD and ASD among Danish and Finnish children.

BACKGROUND: Some studies have indicated an increased risk of attention deficit hyperactivity disorder (ADHD) and a small, sex-specific association with autism spectrum disorder (ASD) among children prenatally exposed to obstetric oxytocin. Since oxytocin is widely used in the obstetric ward, these potentially deleterious effects are of concern. Thus, we aimed to examine whether obstetric oxytocin treatment for labour induction or augmentation is associated with ADHD and ASD in offspring born in a two-country design based on data from Denmark and Finland. METHODS: This population-based study used data from national registers in Denmark and Finland. Singletons born in Denmark 2000-10 (n = 577 380) and Finland 1991-2010 (n = 945 543), who survived infancy, were followed until 31 December 2015. ADHD and ASD were defined using diagnostic codes. For ADHD, we also included information on prescribed and redeemed ADHD medication in the definition. Hazards ratios (HRs) with 95% confidence intervals (CI), modelled with age as the underlying time scale, were calculated to estimate the associations. RESULTS: Oxytocin was used in 31% and 46% of the included deliveries in Denmark and Finland, respectively. In crude analyses, prenatal oxytocin was associated with an approximately 20% increased risk of ADHD and ASD, but confounder adjustment attenuated the association. The adjusted HR was 1.03, 95% CI 1.01-1.05, for ADHD and 1.05, 95% CI 1.02-1.08, for ASD. The results were similar in across country and gender. CONCLUSIONS: We found an association between synthetic oxytocin and ADHD or ASD which is unlikely to reflect a causal association and thus should not support the concern of clinical use. Our results help to allay concerns of obstetric use of oxytocin causing ADHD or ASD.

Prenatal phthalate exposures and autism spectrum disorder symptoms in low-risk children.

BACKGROUND: Prenatal exposure to environmental chemicals has been associated with Autism Spectrum Disorder (ASD) symptoms in some, but not all, studies, but most research has not accounted for other childhood behavior problems. OBJECTIVES: To evaluate the specific associations of prenatal phthalate exposures with ASD symptoms in children (ages 3-6) accounting for other behavior problems, and to assess sex differences in these associations. METHODS: We measured phthalate metabolites in prenatal urine samples. Mothers completed the Social Responsiveness Scale-2nd edition (SRS-2) to assess child ASD symptoms and the Child Behavior Checklist (CBCL) to assess general behavior problems. We assessed associations of the sum of di-(2-ethylhexyl) phthalate metabolites, monobutyl phthalate, mono-isobutyl phthalate, and monoethyl phthalate (mEP) with ASD symptoms, adjusting for other behavior problems, using linear regression models (n=77). RESULTS: Most associations were null, and the sample size limited power to detect associations, particularly in the stratified analyses. After adjusting for internalizing and externalizing problems from the CBCL, ASD symptoms increased for each doubling of prenatal mEP concentration among boys only. CONCLUSIONS: Further investigation of maternal prenatal urinary phthalate metabolite concentrations and ASD symptoms while adjusting for other behavioral problems is warranted.

Placental pathology, corticotropin-releasing hormone, timing of parturition, and fetal growth in the pregnancy outcomes and community health study.

Background: Identification of vascular pathologies in delivered placentas and their associations with biomarkers measured during pregnancy may elucidate mechanisms of adverse pregnancy outcomes and inform early detection and intervention strategies.Objectives: To examine associations of placental vascular pathology with birth size and timing of parturition, and to evaluate maternal midpregnancy serum corticotropin-releasing hormone (CRH) levels as a marker of the above associations.Study design: The pregnancy outcomes and community health (POUCH) Study enrolled women at 16-27 weeks of pregnancy from five Michigan communities. Histological assessments of delivered placentas and assays of CRH in maternal blood sampled at enrollment were performed in a subcohort of 1152 participants. Five placental vascular pathology constructs were formulated: Maternal-Vascular-Obstructive (MVO), Fetal Vascular-Obstructive (FVO), Maternal Vascular-disturbance of Integrity (MVI), Fetal Vascular-disturbance of Integrity (FVI), and Maternal Vascular-Developmental (MVD). A four-level outcome variable combined small for gestational (SGA) yes/no and delivery timing preterm/term; the non-SGA/term served as the referent group. In multinomial logistic regression models, the five vascular pathology groups were evaluated in relation to the outcome variable and effect sizes were compared before versus after exclusion of participants with high CRH (top quartile).Results: Adjusted odds ratios (aOR) for MVO among SGA/term and SGA/preterm were 4.1 (95% CI: 2.2, 7.9) and 8.8 (95% CI: 3.3, 23.5) respectively. Among SGA/preterm births, the aOR was attenuated by ∼40%, i.e. 5.4 (95% CI: 1.1, 26.2) after removing high CRH pregnancies. MVI and FVO were each associated with SGA/preterm, aOR = 3.7 (95% CI: 1.3, 10.3) and 10.5 (95% CI: 3.6, 30.8) respectively. Removal of high CRH pregnancies reduced the OR estimates by nearly half, i.e. MVI aOR = 1.9 (95% CI: 0.34, 10.9), FVO aOR = 6.0 (95% CI: 1.3, 28.6). MVI, FVI and MVD were each associated with greater odds of non-SGA/preterm, but the aORs showed little change after removing high CRH pregnancies.Conclusions: Obstructive placental vascular pathologies in maternal or fetal vessels are associated with SGA. High CRH levels coincided with a portion of pregnancies that share these complications, particularly among pregnancies that also ended prematurely.

Inhibited temperament and parent emotional availability differentially predict young children's cortisol responses to novel social and nonsocial events.

Preschool-aged children (n = 274) were examined in the laboratory to assess behavioral and cortisol responses to nonsocial and social threat. Parents also responded to scales on the Children's Behavior Questionnaire reflecting exuberant approach to novel/risky activities (reversed scored) and shyness. Multi-method measures of Nonsocial and Social Inhibition were computed. Parents and children were observed engaging in a series of interactive tasks and the Emotional Availability scales were scored for parental sensitivity, nonintrusiveness, nonhostility, and structuring. These scores were factored to yield one measure of Parenting Quality. Analyses revealed that Nonsocial and Social Inhibition could be distinguished and that associations with cortisol response were stressor specific. Moderation analyses revealed that parenting quality buffered cortisol elevations for extremely socially, but not nonsocially inhibited children. These findings are consistent with evidence that sensitive, supportive parenting is an important buffer of the HPA axis response to threat in infants and toddlers, and extends this finding to the preschool period.

To spear or not to spear: comparison of saliva collection methods.

The eye spear, or an absorbent sponge-like material, has been proposed as a useful method of obtaining repeated saliva samples from infants and young children for cortisol determination. This brief report examines possible interference effects of different types of eye spears under conditions of relatively high and low cortisol levels, with or without the use of oral stimulant, and using two common assays. In Study 1, one type of eye spear was compared to passively collected drool using two different assays (EIA, DELFIA), across high and low concentrations of cortisol. No differences were found between methods for either assay or cortisol level, indicating that the spears are potentially a viable method of collecting saliva. Study 2 compared three other types of absorbent eye spears to passive drooling under the presence or absence of oral stimulant use. This study revealed that the degree of interference varied as a function of the specific type of eye spear that was employed; stimulant use had no effect. Taken together, the results raise important considerations to take into account when selecting collection materials and procedures in the measurement of salivary cortisol.

Fearful Temperament and Stress Reactivity Among Preschool-Aged Children.

In this study, we examined the relation between physiological stress-reactivity and temperamental fearfulness in 162 preschool-aged children. Both the autonomic and neuroendocrine arms of the mammalian stress system were examined. Larger stress responses were defined as greater sympathetic activation, parasympathetic withdrawal and cortisol increases to stressor tasks. Fearful temperament was examined using parent report and behavior in response to fear-evocative laboratory tasks. There was little evidence that larger sympathetic activation or parasympathetic withdrawal was associated with fearful temperament. Greater cortisol reactivity, however, was associated with fearful temperament. Additional analyses examined those children who were consistently fearful across all measures, and the results remained largely the same. However, there was some suggestion that consistently fearful compared to non-fearful children might be more likely to exhibit sympathetic activation to the fear-evocative stimuli. These findings provide support for the argument that fearful temperament is associated with greater stress reactivity in young children. Nonetheless the size of the associations was small and future studies will need to determine whether reactivity of stress-sensitive physiological systems contributes to the development of individual differences in fearful temperament or merely reflects these differences.

Click-evoked auditory brainstem responses and autism spectrum disorder: A meta-analytic review.

Behavior does not differentiate ASD risk prior to 12 months of age, but biomarkers may inform risk before symptoms emerge. Click-evoked auditory brainstem responses (ABRs) may be worth consideration due to their measurement properties (noninvasiveness; reliability) and conceptual features (well-characterized neural generators), but participant characteristics and assessment protocols vary considerably across studies. Our goal is to perform a meta-analysis of the association between ABRs and ASD. Following an electronic database search (PubMed, Medline, PsycInfo, PsycArticles), we included papers that were written in English, included ASD and typically-developing (TD) groups, and reported the information needed to calculate standardized mean differences (Hedges's g) for at least one ABR latency component (I, III, V, I-III, III-V, I-V). We weighted and averaged effect sizes across conditions and subsets of participants to yield one estimate per component per study. We then performed random-effects regressions to generate component-specific estimates. ASD was associated with longer ABR latencies for Waves III (g = 0.5, 95% CI 0.1, 0.9), V (g = 0.7, 95% CI 0.3, 1.1), I-III (g = 0.7, 95% CI 0.2, 1.2), and I-V (g = 0.6, 95% CI 0.2, 1.0). All components showed significant heterogeneity. Associations were strongest among participants ≤8 years of age and those without middle ear abnormalities or elevated auditory thresholds. In sum, associations between ABRs and ASD are medium-to-large in size, but exhibit heterogeneity. Identifying sources of heterogeneity is challenging, however, due to power limitations and co-occurrence of sample/design characteristics across studies. Research addressing the above limitations is crucial to determining the etiologic and/or prognostic value of ABRs for ASD. Autism Res 2018, 11: 916-927. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Auditory brainstem responses (ABR) may be associated with ASD, but participant characteristics and assessment protocols vary considerably across individual studies. Our goal is to combine the results across these studies to facilitate clarity on the topic. Doing so represents a first step in evaluating whether ABRs yield potential for informing the etiology of ASD risk and/or ASD symptom profiles.

Labor augmentation during birth and later cognitive ability in young adulthood.

PURPOSE: Synthetic oxytocin for labor augmentation during birth has been linked to negative neurodevelopment effects in children. We examined whether maternal labor augmentation was associated with lower cognitive ability in young adulthoods. PATIENTS AND METHODS: We identified 330,107 individuals (96.6% were men), with noninduced labor and with a cognitive ability test score, the Børge Priens Prøve (BPP) score, from draft board examinations in 1995-2015 (mean age, 18.8 years). Information on maternal labor augmentation was ascertained from the Danish Medical Birth Register, and we calculated mean differences in the BPP score according to maternal labor augmentation. We repeated our analyses in a sub-sample of siblings to control for unmeasured familial confounding. RESULTS: Maternal labor augmentation was not associated with any noticeable decline in cognitive ability. However, the difference in the mean BPP score for exposure to maternal labor augmentation varied according to maternal parity, as the mean difference in BPP scores increased with increasing parity, in nulliparous: mean difference=-0.14 (95% CI=-0.23 to -0.04); in maternal parity 4+: mean difference=-1.21 (95% CI=-2.905 to -0.37). The sibling analysis showed little influence of shared familial factors on the association. CONCLUSION: The mean BPP was slightly lower among labor augmented compared to nonaugmented and with an increasing difference with increasing parity. However, the differences were small and could not be considered of any clinical relevance. Furthermore, the sibling analyses suggested little confounding by familial factors.

Correction: Assisted Reproductive Technology and Newborn Size in Singletons Resulting from Fresh and Cryopreserved Embryos Transfer.

[This corrects the article DOI: 10.1371/journal.pone.0169869.].

Preterm delivery trends by maternal race/ethnicity in the United States, 2006-2012.

PURPOSE: To estimate changes in preterm delivery (PTD) in the United States from 2006 to 2012 by clinical circumstance, timing of delivery, and race/ethnicity. METHODS: We used vital statistics natality data on all singleton live births from the 18 U.S. states continuously using the 2003 birth certificate from 2006 to 2012. We estimated change in PTD overall and by clinical circumstance (spontaneous vs. medically indicated) and delivery timing among all women and by race/ethnicity, using descriptive and multivariable regression methods. RESULTS: Overall, indicated, and spontaneous PTD declined by 10.31%, 8.40%, and 11.52%, respectively. Late-preterm, early-term, and post-term deliveries decreased substantially (12.13%, 18.37%, and 32.20%, respectively), with simultaneous increase (13.57%) in full-term deliveries. Non-Hispanic white, non-Hispanic black, and Asian/Pacific Islander women experienced larger declines in PTD compared with Hispanic and American Indian/Alaska Native women. Non-Hispanic white women experienced larger declines in late and medically indicated PTD, while non-Hispanic black women experienced larger declines in early and moderate and spontaneous PTD. CONCLUSIONS: Overall, spontaneous, and indicated PTD declined from 2006 to 2012. Declines were lower than previously reported and differed substantially by race/ethnicity.