Associations of LINE-1 DNA Methylation with Preterm Birth in a Prospective Cohort Study

Preterm birth affects over 12% of all infants born in the US yet the biology of early delivery remains unclear, including whether epigenetic mechanisms are involved. We examined associations of maternal and umbilical cord blood long interspersed nuclear element-1 (LINE-1) DNA methylation with length of gestation and odds of preterm birth in singleton pregnancies in Project Viva. In white blood cells from maternal blood during 1(st) trimester (n=914) and 2(nd) trimester (n=922), and from venous cord blood at delivery (n=557), we measured LINE-1 by pyrosequencing (expressed as %5 methyl cytosines within the LINE-1 region analyzed [%5mC]). We ran linear regression models to analyze differences in gestation length, and logistic models for odds of preterm birth (<37 v. 6537 weeks gestation), across quartiles of LINE-1. Mean(SD) LINE-1 levels were 84.3(0.6), 84.5(0.4), and 84.6(0.7) %5mC for 1(st) trimester, 2(nd) trimester and cord blood, respectively. Mean(SD) gestational age was 39.5(1.8) weeks, and 6.5% of infants were born preterm. After adjustment for maternal age, race/ethnicity, BMI, education, smoking status, and fetal sex, women with the highest vs. lowest quartile of 1(st) trimester LINE-1 had longer gestations (0.45 weeks [95% CI 0.12, 0.78]) and lower odds of preterm birth (OR 0.40 [0.17, 0.94]), whereas associations with cord blood LINE-1 were in the opposite direction (-0.45 weeks, -0.83, -0.08) and (OR 4.55 [1.18, 17.5]). In conclusion, higher early pregnancy LINE-1 predicts lower risk of preterm birth. In contrast, preterm birth is associated with lower LINE-1 in cord blood

Height and risk of death among men and women: aetiological implications of associations with cardiorespiratory disease and cancer mortality

OBJECTIVES: Height is inversely associated with cardiovascular disease mortality risk and has shown variable associations with cancer incidence and mortality. The interpretation of findings from previous studies has been constrained by data limitations. Associations between height and specific causes of death were investigated in a large general population cohort of men and women from the West of Scotland. DESIGN: Prospective observational study. SETTING: Renfrew and Paisley, in the West of Scotland. SUBJECTS: 7052 men and 8354 women aged 45-64 were recruited into a study in Renfrew and Paisley, in the West of Scotland, between 1972 and 1976. Detailed assessments of cardiovascular disease risk factors, morbidity and socioeconomic circumstances were made at baseline. MAIN OUTCOME MEASURES: Deaths during 20 years of follow up classified into specific causes. RESULTS: Over the follow up period 3347 men and 2638 women died. Height is inversely associated with all cause, coronary heart disease, stroke, and respiratory disease mortality among men and women. Adjustment for socioeconomic position and cardiovascular risk factors had little influence on these associations. Height is strongly associated with forced expiratory volume in one second (FEV1) and adjustment for FEV1 considerably attenuated the association between height and cardiorespiratory mortality. Smoking related cancer mortality is not associated with height. The risk of deaths from cancer unrelated to smoking tended to increase with height, particularly for haematopoietic, colorectal and prostate cancers. Stomach cancer mortality was inversely associated with height. Adjustment for socioeconomic position had little influence on these associations. CONCLUSION: Height serves partly as an indicator of socioeconomic circumstances and nutritional status in childhood and this may underlie the inverse associations between height and adulthood cardiorespiratory mortality. Much of the association between height and cardiorespiratory mortality was accounted for by lung function, which is also partly determined by exposures acting in childhood. The inverse association between height and stomach cancer mortality probably reflects Helicobacter pylori infection in childhood resulting inor being associated withshorter height. The positive associations between height and several cancers unrelated to smoking could reflect the influence of calorie intake during childhood on the risk of these cancers

Quantification of selection bias in studies of risk factors for birth defects among livebirths

Background: Risk factors for birth defects are frequently investigated using data limited to liveborn infants. By conditioning on survival, results of such studies may be distorted by selection bias, also described as “livebirth bias.” However, the implications of livebirth bias on risk estimation remain poorly understood. Objectives: We sought to quantify livebirth bias and to investigate the conditions under which it arose. Methods: We used data on 3994 birth defects cases and 11 829 controls enrolled in the National Birth Defects Prevention Study to compare odds ratio (OR) estimates of the relationship between three established risk factors (antiepileptic drug use, smoking, and multifetal pregnancy) and four birth defects (anencephaly, spina bifida, omphalocele, and cleft palate) when restricted to livebirths as compared to among livebirths, stillbirths, and elective terminations. Exposures and birth defects represented varying strengths of association with livebirth; all controls were liveborn. We performed a quantitative bias analysis to evaluate the sensitivity of our results to excluding terminated and stillborn controls. Results: Cases ranged from 33% liveborn (anencephaly) to 99% (cleft palate). Smoking and multifetal pregnancy were associated with livebirth among anencephaly (crude OR [cOR] 0.61 and cOR 3.15, respectively) and omphalocele cases (cOR 2.22 and cOR 5.22, respectively). For analyses of the association between exposures and birth defects, restricting to livebirths produced negligible differences in estimates except for anencephaly and multifetal pregnancy, which was twofold higher among livebirths (adjusted OR [aOR] 4.93) as among all pregnancy outcomes (aOR 2.44). Within tested scenarios, bias analyses suggested that results were not sensitive to the restriction to liveborn controls. Conclusions: Selection bias was generally limited except for high mortality defects in the context of exposures strongly associated with livebirth. Findings indicate that substantial livebirth bias is unlikely to affect studies of risk factors for most birth defects

Parental smoking in pregnancy and the risks of adult-onset hypertension

Fetal exposure to parental smoking may lead to developmental adaptations and promote various diseases in later life. This study evaluated the associations of parental smoking during pregnancy with the risk of hypertension in the daughter in adulthood, and assessed whether these associations are explained by birth weight or body weight throughout life. We used data on 33 086 participants of the Nurses' Health Study II and the Nurses' Mothers' Cohort. Cox proportional hazards models were used to examine the associations of maternal and paternal smoking during pregnancy with the nurse daughter, with self-reported physician-diagnosed hypertension from 1989 until 2007. Overall, 8575 (25.9%) mothers and 18 874 (57.0%) fathers smoked during pregnancy. During follow-up, 7825 incident cases of adult-onset hypertension were reported. Both maternal and paternal smoking of ≥15 cigarettes/d during pregnancy were associated with increased risks of hypertension (rate ratio, 1.19; 95% CI, 1.09-1.29; and rate ratio, 1.18; 95% CI, 1.12-1.25, respectively) in the age-adjusted models. Further adjustment for birth weight did not affect the effect estimates appreciably, whereas additional adjustment for body shape and weight until age 18, or current body mass index, attenuated the associations with both maternal and paternal smoking (rate ratio, 1.07; 95% CI, 0.98-1.16; and rate ratio, 1.06; 95% CI, 1.01-1.12, respectively). The associations of parental smoking during pregnancy with the risk of hypertension in the offspring were largely explained by body weight throughout life, suggesting that these associations may not reflect direct intrauterine mechanisms

Menstrual Cycle Regularity and Length Across the Reproductive Lifespan and Risk of Cardiovascular Disease

Importance: Menstrual cycle characteristics may be associated with an increased risk of cardiovascular disease (CVD). However, existing studies are limited, and few have explored the mediating role of established CVD risk factors. Objective: To explore the associations of menstrual cycle characteristics across the reproductive lifespan with the risk of CVD and to what extent these associations were mediated by hypercholesterolemia, chronic hypertension, and type 2 diabetes. Design, Setting, and Participants: This cohort study prospectively followed Nurses' Health Study II participants between 1993 and 2017 who reported menstrual cycle regularity and length for ages 14 to 17 years and 18 to 22 years at enrollment in 1989 and updated current cycle characteristics in 1993 (at ages 29 to 46 years). Data analysis was performed from October 1, 2019, to January 1, 2022. Exposures: Menstrual cycle regularity and length across the reproductive lifespan. Main Outcomes and Measures: Incident CVD events of interest, including fatal and nonfatal coronary heart disease (CHD; myocardial infarction [MI] or coronary revascularization) and stroke. Results: A total of 80 630 Nurses' Health Study II participants were included in the analysis, with a mean (SD) age of 37.7 (4.6) years and body mass index of 25.1 (5.6) at baseline. Over 24 years of prospective follow-up, 1816 women developed their first CVD event. Multivariable Cox proportional hazards models showed that, compared with women reporting very regular cycles at the same ages, women who had irregular cycles or no periods at ages 14 to 17, 18 to 22, or 29 to 46 years had hazard ratios for CVD of 1.15 (95% CI, 0.99-1.34), 1.36 (95% CI, 1.06-1.75), and 1.40 (95% CI, 1.14-1.71), respectively. Similarly, compared with women reporting a cycle length of 26 to 31 days, women reporting a cycle length 40 days or more or a cycle too irregular to estimate from ages 18 to 22 or 29 to 46 years had hazard ratios for CVD of 1.44 (95% CI, 1.13-1.84) and 1.30 (95% CI, 1.09-1.57), respectively. Mediation analyses showed that subsequent development of hypercholesteremia, chronic hypertension, and type 2 diabetes only explained 5.4% to 13.5% of the observed associations. Conclusions and Relevance: In this cohort study, both irregular and long menstrual cycles were associated with increased rates of CVD, which persisted even after accounting for subsequently established CVD risk factors.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Association of birth by cesarean delivery with obesity and type 2 diabetes among adult women

Importance Cesarean delivery is associated with an increased risk of childhood obesity in offspring. However, whether this increased risk also includes obesity-associated conditions remains unclear. Objective To evaluate the association of birth by cesarean delivery with offspring’s risks of obesity and type 2 diabetes in adulthood. Design, Setting, and Participants This prospective cohort study compared the incidence of obesity and type 2 diabetes between birth by cesarean delivery and vaginal delivery among 33 226 women participating in the Nurses’ Health Study II who were born between 1946 and 1964, with follow-up through the end of the 2013-2015 follow-up cycle. Participants’ mothers provided information on mode of delivery and pregnancy characteristics. Participants provided information every 2 years on weight and diagnosis of type 2 diabetes. Relative risks of obesity and type 2 diabetes were estimated using log-binomial and proportional hazards regression accounting for maternal body mass index and other confounding factors. Statistical analysis was performed from June 2017 to December 2019. Exposure Birth by cesarean delivery compared with birth by vaginal delivery. Main Outcomes and Measures Risk of obesity and incidence of type 2 diabetes. Results At baseline, the participants’ mean (SD) age was 33.8 (4.6) years (range, 24.0-44.0 years). A total of 1089 of the 33 226 participants (3.3%) were born by cesarean delivery. After 1 913 978 person-years of follow-up, 12 156 (36.6%) women were obese and 2014 (6.1%) had received a diagnosis of type 2 diabetes. Women born by cesarean delivery were more likely to be classified as obese and to have received a diagnosis of type 2 diabetes during follow-up. The multivariable-adjusted relative risk of obesity among women born by cesarean vs vaginal delivery was 1.11 (95% CI, 1.03-1.19). The multivariable-adjusted hazard ratio for type 2 diabetes among women born by cesarean vs vaginal delivery was 1.46 (95% CI, 1.18-1.81); this association remained significant after additional adjustment for participant’s own body mass index (relative risk, 1.34 [95% CI, 1.08-1.67]). These associations persisted when analyses were restricted to women at low risk of cesarean delivery based on maternal characteristics. Conclusions and Relevance This study suggests that women born by cesarean delivery may have a higher risk than women born by vaginal delivery of being obese and developing type 2 diabetes during adult life

Sociodemographic characteristics influencing birth outcome in Sweden, 1908-1930. Birth variables in The Population Study of Women in Gothenburg

STUDY OBJECTIVE—To identify variables available in early Swedish delivery records and their relation to birth outcomes for home and hospital deliveries in Gothenburg at the early part of this century.
DESIGN—A retrospective recovery of original delivery records and social variables in a cross sectional population.
SETTING—Gothenburg, Sweden.
PARTICIPANTS—851 fullterm singleton female births with known gestational age born into five birth cohorts on selected dates (1908, 1914,( )1918, 1922 and 1930).
MAIN RESULTS—Delivery site, maternal parity, gestational age, and social group were significant factors influencing birth outcome as birth weight and length. The mean birth weight and length of hospital born infants was consistently lower than for home deliveries across all cohorts. Site of delivery changed significantly during the period of births under study, 1908-1930.
CONCLUSIONS—In this study, which was based on original delivery records from the early part of this century, it was found that delivery site was an important factor influencing birth outcome across five birth cohorts. Utilisation of delivery services changed during the period of study. Thus, to avoid selection bias, the application of delivery records should reflect the birthing practice of the time period in question.


Keywords: sociodemographic; birth weight; birth length; delivery sit