Eric P. Elkin

Fetal growth retardation in infants of multiparous and nulliparous women with preeclampsia

OBJECTIVE Infants of women with preeclampsia are considered at high risk of fetal growth retardation. The purpose of our study was to determine whether the risk differed by parity. STUDY DESIGN We compared the outcomes of 133 case patients with preeclampsia (101 nulliparous women and 32 multiparous women) and 132 normotensive control patients (52 nulliparous women and 80 multiparous women) who delivered at Northern California Kaiser Permanente hospitals between 1984 and 1985. RESULTS Women with preeclampsia were more likely than control patients to deliver a small-for-gestational-age infant (adjusted odds ratio 7.0, 95% confidence interval 2.8 to 18.1). After we controlled for smoking status, age, Quetelet index, and race, multiparous women with preeclampsia were at greater risk of having a small-for-gestational-age infant (adjusted odds ratio 29.4, 95% confidence interval 5.2 to 167.5) than were nulliparous women (adjusted odds ratio 4.1, 95% confidence interval 1.2 to 14.1) when compared with normotensive control patients of similar parity. Although multiparous women with preeclampsia had higher mean arterial pressures and somewhat earlier onsets of elevated mean arterial pressure than nulliparous women with preeclampsia, neither of these variables predicted whether the infants would be small for gestational age. CONCLUSION Multiparous women with preeclampsia are at higher risk of having an infant with fetal growth retardation than are nulliparous women with preeclampsia.

A case-control pilot study of traffic exposures and early childhood leukemia using a geographic information system.

The scientific debate on risk relationships between proximity to electric and magnetic fields and the development of childhood leukemia has recently focused on the role of other factors that may be strongly correlated with power lines. Proximity to high traffic density, as defined by major roadways or automobile counts, and associated socioeconomic neighborhood characteristics have been suggested as potentially important confounders. For traffic or socioeconomic status (SES) to confound any EMF effect these factors would need to have their own independent impact on leukemia risk. This study was designed to use geographic information system (GIS) technology to empirically examine the relationship between traffic density and socioeconomic indicators to early childhood leukemia in an urban area of California. Ninety cases of childhood leukemia diagnosed under the age of five between 1988 and 1994 among children born in San Diego County were matched by gender and birth date to a total of 349 children also born in the county and not known to have developed any cancer. Case-control differences were assessed via conditional logistic regression. No significant differences were observed for the neighborhood median family income of the birth residences. When comparing neighborhoods with median annual income > or =

Declining semen quality: can the past inform the present?

56,000 to those with incomes < or =

Cancer in California school employees, 1988-1992.

18,000 the odds ratio was 0.86 (95% confidence interval 0.31, 2.38). Traffic density was measured using a variety of methods, including information on average daily traffic counts and road characteristics. None of the measures of traffic were associated with case status. Neither SES or traffic density near the birth address as assessed with GIS methods are strong enough risk factors for leukemia to be confounders which could totally explain the effect of another variable (such as wire code). Associations with the diagnosis address or with more direct exposure measures may differ from those reported here.

The Question of Declining Sperm Density Revisited: An Analysis of 101 Studies Published 1934-1996

By using instrumentation initially designed for counting white blood cells, sperm counts have been utilized by clinicians since 1929, particularly to evaluate cases of suspected infertility. Although this basic biological parameter might be assumed to be stable over time, several studies over the past 20 years have suggested a decline in sperm count or density. The most controversial of these analyses was published in 1992. A flood of criticism followed this analysis of 61 studies that found a 50% decline in sperm density between 1938 and 1990. Critics suggested that historical methods (of counting sperm or conducting studies) were variable and unreliable, differing from modern methods both qualitatively and quantitatively. To address this issue we analyzed these studies for trends in counting methods or their variability. We found neither. Alternative analyses produced some differences in trend estimates, but statistical factors alone could not account for the total decline in sperm density. We reviewed study populations to identify trends in population characteristics, such as abstinence time, that might explain the decline. However, controlling analytically for such factors only increased the rate of decline. We conclude that historical data on sperm density, despite large random error, are surprisingly reliable. Nonetheless, understanding causes of temporal and geographic differences in sperm density must await contemporary data.

Have sperm densities declined? A reanalysis of global trend data.

BACKGROUND Periodic concerns about excesses of cancer among teachers in California schools prompted our examination of cancer incidence in California school employees. METHODS Records of school employees between 1987-1992 were linked to the California Cancer Registry of incident cases diagnosed 1988-1992. Sex-, race-, and age-adjusted standardized incidence ratios were calculated for specific cancer sites. Analyses stratified by sex, race/ethnicity, and job assignment were also performed. RESULTS Melanoma of the skin, thyroid cancer, prostate cancer, and female cancers of the breast, uterus, and ovary all occurred more frequently than expected in these school employees. In contrast, cancers of the respiratory system, oral cavity, digestive system, urinary system, and uterine cervix occurred less frequently. CONCLUSIONS The incidence of cancers thought to be related to hormones and/or higher socioeconomic status appeared elevated while cancers often linked to smoking and/or alcohol intake occurred less frequently in this large cohort of professional school employees.