Eun Hee Ha

Maternal exposure to particulate air pollution and term birth weight : a multi-country evaluation of effect and heterogeneity

Background: A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent. Objectives: We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association. Methods: Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM10 and PM2.5 (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates. Results: In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m3 increase in PM10 [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM2.5 (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m3 increase in PM10 exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (–8.9 g; 95% CI: –13.2, –4.6 g). Meta-regressions revealed that centers with higher median PM2.5 levels and PM2.5:PM10 ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations. Conclusion: Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.

Ischemic stroke associated with decrease in temperature

Background Some studies suggest low temperatures can affect mortality, especially deaths associated with circulatory and respiratory conditions. Methods We investigated the association between ischemic stroke onset and decrease in temperature in 545 patients over a 3-year period (January 1998 to December 2000) in Incheon, Korea. We used a case-crossover study design to assess changes in the risk of ischemic stroke during a brief hazard period after exposure to decrease in temperature. For each subject, the case period was matched to 2 control periods exactly 1 week before and after onset of the ischemic stroke. Results Decreased ambient temperature was associated with risk of acute ischemic stroke. The strongest effect was seen on day after exposure to cold weather. The odds ratio (OR) for an interquartile range decrease in temperature was 2.9 (95% confidence interval [CI] = 1.5–5.3). The risk period was 24-48 hours after cold exposure. Risk estimates associated with decreased temperature were greater in the winter than in the summer. Women, persons greater than 65 years of age, nonobese persons, and those with previous hypertension or hypercholesterolemia were more susceptible to cold-induced ischemic stroke. Conclusions These results suggest that stroke occurrence rises with decreasing temperature, and that even a moderate decrease in temperature can increase the risk of ischemic stroke. Susceptible people should take steps to protect themselves from cold, especially in the winter.

Prenatal Exposure to Phthalates and Infant Development at 6 Months: Prospective Mothers and Children’s Environmental Health (MOCEH) Study

Background: There are increasing concerns over adverse effects of prenatal phthalate exposure on the neurodevelopment of infants. Objectives: Our goal was to explore the association between prenatal di(2-ethylhexyl) phthalate and dibutyl phthalate exposure and the Mental and Psychomotor Developmental Indices (MDI and PDI, respectively) of the Bayley Scales of Infant Development at 6 months, as part of the Mothers and Children’s Environmental Health Study. Methods: Between 2006 and 2009, 460 mother–infant pairs from Seoul, Cheonan, and Ulsan, Korea, participated. Prenatal mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MBP) were measured in one urine sample acquired from each mother during the third trimester of pregnancy. Associations with log-transformed creatinine-corrected phthalate concentrations were estimated using linear regression models adjusted for potential confounders. Results: MDI was inversely associated with the natural log concentrations (micrograms per gram creatinine) of MEHHP [β = –0.97; confidence interval (CI), –1.85 to –0.08] and MEOHP (β = –0.95; CI, –1.87 to –0.03), and PDI was inversely associated with MEHHP (β = –1.20; CI, –2.33 to –0.08). In males, MDI was inversely associated with MEHHP (β = –1.46; CI, –2.70 to –0.22), MEOHP (β = –1.57; CI, –2.87 to –0.28), and MBP (β = –0.93; CI, –1.82 to –0.05); PDI was inversely associated with MEHHP (β = –2.36; CI, –3.94 to –0.79), MEOHP (β = –2.05; CI, –3.71 to –0.39), and MBP (β = –1.25; CI, –2.40 to –0.11). No significant linear associations were observed for females. Conclusions: The results suggest that prenatal exposure to phthalates may be inversely associated with the MDI and PDI of infants, particularly males, at 6 months.

PM10 and Pregnancy Outcomes : A Hospital-Based Cohort Study of Pregnant Women in Seoul

Objective: The aim of this study was to evaluate the effects of PM10 on birth outcomes using a prospective cohort of pregnant women. Methods: The multicenter prospective study was conducted in Korea from 2001 to 2004. To estimate the effects of PM10 exposure on birth outcomes, the logistic and linear regression model and the generalized additive model for nonlinear relationships were used. Results: Stillbirths were affected by PM10 level during the third trimesters (OR = 1.10, 95% CI = 1.02–1.14), and birth defects were influenced by the PM10 exposure during the second trimesters (OR = 1.16, 95% CI = 1.00–1.34). Intrauterine growth retardation was affected by the first trimesters PM10 exposure. On the other hand, premature birth was affected by the PM10 exposure during the third trimester, and low-birth-weight births were affected by the PM10 level during entire trimesters of pregnancy. Conclusions: PM10 exposure during pregnancy may result in adverse birth outcomes with different critical periods.

Association between pre‐pregnancy body mass index and socioeconomic status and impact on pregnancy outcomes in Korea

Aim:  To compare socioeconomic status and pregnancy outcomes in relation to different pre‐pregnancy body mass index (BMI) levels, and to determine whether gestational weight gain is related to socioeconomic status and pregnancy outcomes.

Serum High-Density Lipoprotein Cholesterol and Breast Cancer Risk by Menopausal Status, Body Mass Index, and Hormonal Receptor in Korea

High-density lipoprotein cholesterol (HDL-C) has been suggested to be associated with breast cancer. However, the roles of HDL-C and hypertriglyceridemia on breast cancer still have been controversial. The goal of this study was to investigate the association between HDL-C with breast cancer risk, stratifying by menopausal status, and body mass index. The hormonal receptor status of breast has been proposed to modify the effect of HDL-C on breast cancer. Multicenter hospital-based case-control study was conducted from November 2004 to December 2005 in Korea. After one to two individual matchings by age (±5 years) and menopausal status, 690 cases and 1,380 controls were included in the analysis. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by conditional, unconditional, and multinomial logistic regressions. Protective effect of HDL-C on breast cancer was only observed among premenopausal women with an OR (95% CI) of 0.49 (0.33-0.72) for HDL-C ≥60 versus <50 mg/dL (Ptrend < 0.01). Only nonobese premenopausal women had a significant decreased risk (OR, 0.34; 95% CI, 0.22-0.53). OR (95% CI) of low HDL-C (<50 mg/dL) and high triglyceride (TG; ≥150 mg/dL) category was 2.20 (1.32-3.67) on estrogen receptor-negative and progesterone receptor-negative breast cancer compared with high HDL-C (≥50 mg/dL) and low TG (<150 mg/dL) category. This study suggests that higher level of HDL-C may reduce breast cancer risk among premenopausal women. Estrogen receptor-negative and progesterone receptor-negative breast cancer was associated with dyslipidemia, which implicates that association among HDL-C, TG, and breast cancer may be modified by receptor status. (Cancer Epidemiol Biomarkers Prev 2009;18(2):508–15)

The Associations between Social Support, Health-Related Behaviors, Socioeconomic Status and Depression in Medical Students

OBJECTIVES The objective of this study was to estimate the prevalence of depression in medical students and to evaluate whether interpersonal social support, health-related behaviors, and socio-economic factors were associated with depression in medical students. METHODS The subjects in this study were 120 medical students in Seoul, Korea who were surveyed in September, 2008. The subjects were all women and over the age of 20. Their age, body mass index (BMI), quality of sleep, diet, household income, smoking, alcohol consumption, exercise levels, and self-reported health status were surveyed. The degree of perceived social support was measured using the interpersonal support evaluation list (ISEL). Depression was evaluated using the center for epidemiology studies depression scale (CES-D). RESULTS The mean CES-D score was 14.1±8.6 and 37.1% of the participants appeared to suffer from depression. Low levels of perceived interpersonal support increased the risk of depression by more than 10 times and having higher household income did not necessarily decrease the risk of depression. CONCLUSION Medical students have a relatively high level of depression. Efforts should be made to encourage social support in order to promote mental health in medical students.

Risk Factors for Preterm Birth in Korea

Preterm birth is a major determinant of neonatal morbidity and mortality and remains one of the most serious problems in obstetrics. The aim of this study was to investigate the risk factors for preterm birth in Korean pregnant women. A total of 2,645 women were evaluated between 20 and 42 weeks’ gestation at 5 centers using a prospective study design. The patient population is limited to singleton gestations. Demographic factors, socioeconomic statuses, previous and current medical histories, complications of current gestation, and drug and alcohol abuse were evaluated, and univariate and multivariate logistic regression analyses performed. Among nulliparous women, the factors that showed a significant association with preterm delivery were as follows; vaginal bleeding during pregnancy (OR 2.6, CI 1.7–4.2), and below USD 1,000 average income (OR 5.1, CI 1.9–13.5). The factors that showed a significant association with preterm delivery among multiparous women were as follows; a history of spontaneous abortion (OR 2.4, CI 1.1–5.2), and a history of preterm delivery (OR 3.5, CI 1.02–11.8). In conclusion, vaginal bleeding during pregnancy, below USD 1,000 of average income, prior spontaneous abortion, and prior preterm delivery, were positively associated with preterm birth.

Hebei spirit oil spill exposure and subjective symptoms in residents participating in clean-up activities.

Objectives This study was conducted to examine the relationship between crude oil exposure and physical symptoms among residents participating in clean-up work associated with the Hebei Spirit oil spill, 2007 in Korea. Methods A total of 288 residents responded to a questionnaire regarding subjective physical symptoms, sociodemographic characteristics and clean-up activities that occurred between two and eight weeks after the accident. Additionally, the urine of 154 of the respondents was analyzed for metabolites of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) and heavy metals. To compare the urinary levels of exposure biomarkers, the urine of 39 inland residents who were not directly exposed to the oil spill were analyzed. Results Residents exposed to oil remnants through clean-up work showed associations between physical symptoms and the exposure levels defined in various ways, including days of work, degree of skin contamination, and levels of some urinary exposure biomarkers of VOCs, metabolites and metals, although no major abnormalities in urinary exposure biomarkers were observed. Conclusions This study provides evidence of a relationship between crude oil exposure and acute human health effects and suggests the need for follow-up to evaluate the exposure status and long-term health effects of clean-up participants.

Can Proopiomelanocortin Methylation Be Used as an Early Predictor of Metabolic Syndrome

OBJECTIVE The objectives of this study were to compare early predictive marker of the metabolic syndrome with proopiomelanocortin (POMC) methylation status and to determine the association among birth weight, ponderal index, and cord blood methylation status. RESEARCH DESIGN AND METHODS We collected pregnancy outcome data from pregnant women, cord blood samples at delivery, and blood from children (7–9 years old; n = 90) through a prospective cohort study at Ewha Womans University, MokDong Hospital (Seoul, Korea), from 2003–2005. POMC methylation was assessed by pyrosequencing. We divided subjects into three groups according to cord blood POMC methylation: the low methylation (<10th percentile), mid-methylation, and high methylation (>90th percentile) groups. We analyzed the association of POMC methylation status at birth with adiposity and metabolic components using ANCOVA and multiple linear regression analysis. RESULTS Birth weights (P = 0.01) and ponderal indices (P = 0.01) in the high POMC methylation group were significantly lower than in the mid-POMC methylation group. In terms of metabolic components of childhood, blood triglycerides (57.97, 67.29 vs. 113.89 mg/dL; P = 0.03, 0.01) and insulin (7.10, 7.64 vs. 10.13 μIU/mL; P = 0.05, 0.02) at childhood were significantly higher in the high POMC methylation group than in the low and mid-POMC methylation group. CONCLUSIONS High POMC methylation in cord blood was associated with lower birth weight, and children with high POMC methylation in cord blood showed higher triglycerides and higher insulin concentrations in blood. Thus, POMC methylation status in cord blood may be an early predictive marker of future metabolic syndrome.