Preventing type 2 diabetes: public health implications for women with a history of gestational diabetes mellitus.

There is now strong evidence that lifestyle modification can prevent or delay the development of type 2 diabetes mellitus in high-risk individuals. Women with gestational diabetes mellitus are at increased risk for type 2 diabetes and so are candidates for prevention programs. We review literature on type 2 diabetes risk in women with gestational diabetes, examine current recommendations for postpartum and long-term follow-up, and summarize findings from a 2007 expert-panel meeting. We found data to support that women with gestational diabetes have an increase in risk of type 2 diabetes comparable in magnitude with that of individuals with impaired glucose tolerance and/or impaired fasting glucose and that prevention interventions likely are effective in this population. Current recommendations from leading organizations on follow-up of women after delivery are conflicting and compliance is poor. Clinicians and public health workers face numerous challenges in developing intervention strategies for this population. Translation research will be critical in addressing this important public health issue.

The healthy men study: an evaluation of exposure to disinfection by-products in tap water and sperm quality.

BACKGROUND: Chlorination of drinking water generates disinfection by-products (DBPs), which have been shown to disrupt spermatogenesis in rodents at high doses, suggesting that DBPs could pose a reproductive risk to men. In this study we assessed DBP exposure and testicular toxicity, as evidenced by altered semen quality. METHODS: We conducted a cohort study to evaluate semen quality in men with well-characterized exposures to DBPs. Participants were 228 presumed fertile men with different DBP profiles. They completed a telephone interview about demographics, health history, water consumption, and other exposures and provided a semen sample. Semen outcomes included sperm concentration and morphology, as well as DNA integrity and chromatin maturity. Exposures to DBPs were evaluated by incorporating data on water consumption and bathing and showering with concentrations measured in tap water. We used multivariable linear regression to assess the relationship between exposure to DBPs and adverse sperm outcomes. RESULTS: The mean (median) sperm concentration and sperm count were 114.2 (90.5) million/mL and 362 (265) million, respectively. The mean (median) of the four trihalomethane species (THM4) exposure was 45.7 (65.3) microg/L, and the mean (median) of the nine haloacetic acid species (HAA9) exposure was 30.7 (44.2) microg/L. These sperm parameters were not associated with exposure to these classes of DBPs. For other sperm outcomes, we found no consistent pattern of increased abnormal semen quality with elevated exposure to trihalomethanes (THMs) or haloacetic acids (HAAs). The use of alternate methods for assessing exposure to DBPs and site-specific analyses did not change these results. CONCLUSIONS: The results of this study do not support an association between exposure to levels of DBPs near or below regulatory limits and adverse sperm outcomes in humans.

Genetic epidemiologic studies of preterm birth: guidelines for research.

Over the last decade, it has become increasingly apparent that the cause of preterm birth is multifactorial, involving both genetic and environmental factors. With the development of new technologies capable of probing the genome, exciting possibilities now present themselves to gain new insight into the mechanisms leading to preterm birth. This review aims to develop research guidelines for the conduct of genetic epidemiology studies of preterm birth with the expectation that this will ultimately facilitate the comparison of data sets between study cohorts, both nationally and internationally. Specifically, the 4 areas addressed in this review includes: (1) phenotypic criteria, (2) study design, (3) considerations in the selection of control populations, and (4) candidate gene selection. This article is the product of discussions initiated by the authors at the 3rd International Workshop on Biomarkers and Preterm Birth held at the University of California, Los Angeles, Los Angeles, CA, in March 2005.

The healthy men study: design and recruitment considerations for environmental epidemiologic studies in male reproductive health.

OBJECTIVE: To describe study design, conduct and response, and participant characteristics. DESIGN: Prospective cohort study. SETTING: Participants were male partners of women who were enrolled in a community-based prospective cohort study of drinking water disinfection by-products and pregnancy health. PATIENT(S): Two hundred thirty presumed fertile men recruited from 3 study sites in the United States. INTERVENTION(S): Men completed a telephone interview about demographics, health history, and exposures and provided a semen sample that was express mailed to the study laboratory. MAIN OUTCOME MEASURE(S): Response and participation rates, participant demographics, and lifestyle exposures. RESULT(S): We obtained a high participation rate (84%) among men who were located, but a low overall response rate (25%). Participants were more likely to be white, more highly educated, be married, and have a higher household income than the underlying study cohort. CONCLUSION(S): Our multisite study design may be applicable to the study of community environmental factors and reproductive health of men. Our design was efficient in that men from geographically disparate sites could be recruited, a semen sample was collected at home, and a telephone interview was conducted from a central study site. Despite these design features, the low response rates may suggest selection bias that can be addressed partially in the analysis.

Genetic variation associated with preterm birth: a HuGE review.

Preterm birth (PTB) is a major public health concern because of its high prevalence, associated mortality and morbidity, and expense from both short-term hospitalization and long-term disability. In 2002, 11.9% of U.S. births occurred before 37 weeks gestation. Epidemiologic studies have identified many demographic, behavioral, and medical characteristics associated with PTB risk. In addition, recent evidence indicates a role for genetic susceptibility. We reviewed 18 studies published before June 1, 2004, that examined associations between polymorphisms in the maternal or fetal genome and PTB risk. Studies of a polymorphism in tumor necrosis factor-alpha, a proinflammatory cytokine, showed the most consistent increase in the risk of PTB. Environmental factors such as infection, stress, and obesity, which activate inflammatory pathways, have been associated with PTB, suggesting that environmental and genetic risk factors might operate and interact through related pathways. This review highlights maternal and fetal genetic susceptibilities to PTB, the potential relationships with environmental risk factors, and the need for additional well-designed studies of this critical public health problem.