Exposure to electromagnetic fields during pregnancy with emphasis on electrically heated beds: association with birthweight and intrauterine growth retardation.

Several animal and human studies indicate that fetal growth may be retarded following exposure to electromagnetic fields (EMF). We conducted a prospective study (N = 2,967) to evaluate the relation of birthweight and fetal growth retardation with use of electrically heated beds (electric blankets and heated water beds) during pregnancy. A "nested" study design allowed monitoring of exposure at different stages of pregnancy using both direct and indirect methods.

Occupationally related magnetic field exposure and male subfertility.

Objective: To determine whether there is an association between occupationally related magnetic field exposure, as estimated in milligauss (mG), and male subfertility.

Design: Nested case-control study using three defined case groups and one standard control group.

Setting: Yale New Haven Hospital Infertility Clinic, New Haven, Connecticut.

Tree-based risk factor analysis of preterm delivery and small-for-gestational-age birth.

Using data collected at the Yale-New Haven Hospital, New Haven, Connecticut, in 1980-1982, the authors conducted a tree-based statistical analysis using preterm delivery and small for gestational age as outcomes and the following variables as putative risk factors: maternal age, marital status, ethnicity, education, current employment, smoking, alcohol use, caffeine consumption, marijuana use, hormones/diethylstilbestrol used by the mother, gravidity, parity, and passive smoking. The authors' analyses indicate that ethnicity is a leading factor contributing to both outcomes: Black women are more likely to have preterm deliveries as well as to deliver small-for-gestational age infants. The tree-based procedure leads to generally consistent results with more traditional secondary analyses of the same data set, but also provides a more fully integrated picture of the important relation.

The effectiveness of surgery on the treatment of acute spinal cord injury and its relation to pharmacological treatment.

Using data from the Second National Acute Spinal Cord Injury Study (NASCIS II), the authors sought to characterize the role of surgery in the management of traumatic spinal cord injury and to examine the interaction between pharmacological treatment and surgery. Patients who did not undergo surgery had more severe spinal cord injuries initially than those who had surgery. However, no differences in neurological improvement at 1-year follow-up were found between those who underwent surgery and those who did not.

Clinically useful measures of effect in binary analyses of randomized trials.

The results of a randomized clinical trial can be reported using relative and/or absolute estimators of treatment effect. These various measures convey different information, and the choice can influence the physician's appreciation of the size of treatment effect and, subsequently, treatment decisions. We compare the estimators with respect to the clinically relevant information conveyed to physicians, and identify which clinical questions can and cannot be answered directly by each.

The effect of methylprednisolone, naloxone, and spinal cord trauma on four liver enzymes: observations from NASCIS 2. National Acute Spinal Cord Injury Study.

In order to determine the impact of extremely large doses of methylprednisolone, naloxone, or of spinal cord injury itself, on liver enzymes, we examined the results of SGOT, SGPT, alkaline phosphatase and total bilirubin tests obtained 24 hours, 3 and 10 days after the end of the study drug infusions in spinal cord injured patients entered in the National Acute Spinal Cord Injury Study. The mean values of four liver enzymes, the amount of change between 24 hours and 3 and 10 days post infusion, and the proportion of liver enzyme levels considered to be abnormal did not appear to be affected by either drug protocol. Even when controlling for drug protocol and severity of injury (complete vs incomplete), variation in enzyme levels appeared to be the result of the spinal cord injury, not study drugs.

Human exposure to magnetic fields: a comparative assessment of two dosimeters.

Two types of dosimeters for measuring human exposure to 60 Hz magnetic fields were compared. Fifty adults wore the single-axis, wrist model AMEX (average magnetic field exposure system) and the triple axis, hip-pocket or pouch model AMEX-3D meters for 2 days. Ninety-six percent of the tests were accomplished without apparent dosimeter failure.

Association of delayed conception with caffeine consumption.

This cross-sectional study investigated the relation between intake of caffeine-containing beverages and time to conception in a population of 1,909 married women in New Haven, Connecticut, between May 12, 1980 and March 12, 1982. Women were interviewed shortly after the first prenatal visit regarding the length of time taken to conceive the index pregnancy, consumption of caffeine during pregnancy, and other exposures occurring prior to and during pregnancy. In logistic regression analyses, intake of caffeine from coffee, tea, and caffeinated soft drinks was associated with an increased risk of a delay of conception of 1 year or more.

Effects of timing of methylprednisolone or naloxone administration on recovery of segmental and long-tract neurological function in NASCIS 2.

Previous analyses of the National Acute Spinal Cord Injury Study (NASCIS) have not distinguished recovery of segmental function at the injury level from recovery of the long spinal tracts. Recovery at the injury level could be of considerable clinical significance, but long-tract recovery is the ultimate therapeutic goal. This analysis demonstrates that the greatest proportion of all neurological recovery and of recovery due to treatment with very high doses of methylprednisolone within 8 hours of injury occurs below the lesion.

Possible role of asthma in the risk of preterm labor and delivery.

We assessed the relation between maternal respiratory problems and preterm labor and delivery in a cohort of 3,891 women who delivered a singleton livebirth. Study participants were asked about their medical history in the 12 months before conception; women who reported a history of asthma had a higher risk of preterm labor [relative risk (RR) estimate = 2.33, 95% confidence interval (CI) = 1.

Maternal age: an independent risk factor for cesarean delivery.

Objective: To evaluate whether there is an increased risk of cesarean delivery in women who delay childbearing into their later reproductive years, using a well-defined cohort and controlling for difference in baseline susceptibility such as complications of pregnancy and labor.

Methods: The current study included all women at least 20 years of age delivering their first child and evaluated between 1988-1991 as part of the prospective Yale Health in Pregnancy Study (N = 735). All women planned to deliver at Yale-New Haven Hospital.

Pharmacological treatment of acute spinal cord injury: current status and future projects.

The multicenter, double-blind, randomized second National Acute Spinal Cord Injury Study (NASCIS 2) was conducted to assess the effectiveness of methylprednisolone in improving neurological function after acute spinal cord injury. At 6 weeks, patients treated within 8 hours of injury with methylprednisolone, given as an initial bolus of 30 mg/kg followed by infusion of 5.4 mg/kg/h over 23 hours, demonstrated significantly greater improvement in motor function and touch sensation than did those receiving either naloxone or placebo.

Plasma thyroid hormones and prolactin in premature infants and their mothers after prenatal treatment with thyrotropin-releasing hormone.

We assayed TSH, triiodothyronine, free thyroxine, and prolactin (PRL) in plasma of women and infants participating in a trial of prenatal thyrotropin-releasing hormone (TRH) treatment for prevention of newborn lung disease. Women in labor at 26-34 wk of gestation received 400 micrograms of TRH i.v.

A model for estimating level and net severity of spinal cord injuries.

Objective and detailed neurological assessments are essential in studies of the treatment and the epidemiology of acute spinal cord injuries. In practice, investigators use the expanded score, found by taking the total of the individual determinations, but this summary obscures important detail as to the level and the overall severity of injury. To address this issue, we present a method for estimating level and net severity of injury that makes use of isotonic regression and the Spearman-Kärber estimator.

Risk of congenital malformations associated with proximity to hazardous waste sites.

Concern about environmental pollutants has increased; however, it remains unclear whether chronic exposures to toxic chemicals in the environment occur at doses sufficient to produce adverse health effects in humans. To date, community studies have not adequately addressed this question. In this study, the authors linked two existing data bases of the New York State Department of Health to evaluate the relation between congenital malformations and residential proximity to hazardous waste sites in New York State.

The relationship between acute inflammatory lesions of the preterm placenta and amniotic fluid microbiology.

Objective: Our objective was to determine the relationship between microbial invasion of the amniotic cavity and the presence and severity of acute inflammatory lesions in the placenta.

Study Design: Placental histologic and amniotic fluid microbiologic studies were performed in 92 consecutive patients who were admitted with preterm labor and intact membranes and delivered within 48 hours after amniocentesis.

Results: The prevalence of a positive amniotic fluid culture was 38% (35 of 92).

Congenital defects and electric bed heating in New York State: a register-based case-control study.

Exposure to 60-cycle electromagnetic fields has been hypothesized to be a cause of childhood cancer and congenital defects. Because electric bed heaters are a major source of variation in electromagnetic field exposure in the population, the authors conducted a case-control study in 1988-1989 to examine the relations between congenital defects and the use of electric blankets and heated waterbeds. Cases were identified by the New York State Congenital Malformations Registry as babies with cleft palate (n = 121), cleft lip with or without cleft palate (n = 197), born in 1983-1984, and anencephalus and spina bifida (n = 224), born in 1983-1986, all to upstate New York residents.

The Second National Acute Spinal Cord Injury Study.

In 1990, the Second National Acute Spinal Cord Injury Study reported that high-dosage methylprednisolone improves neurologic recovery in spinal-injured humans. The study showed that patients who received the drug within 8 hr after injury improved, whereas those who received the drug later did not. The drug significantly increased recovery even in severely injured patients who were admitted with no motor or sensory function below the lesion, contradicting a long-held dogma that such patients would not recover.

Respiratory disease in very-low-birthweight infants after prenatal thyrotropin-releasing hormone and glucocorticoid. TRH Study Group.

Although prenatal glucocorticoid treatment reduces neonatal respiratory morbidity, respiratory distress syndrome and chronic lung disease (CLD) develop in many very-low-birthweight infants despite therapy. To investigate the effect of additional prenatal treatment with thyrotropin-releasing hormone (TRH), we did a multicentre, blinded, randomised trial. 404 women with threatened preterm delivery at less than 32 weeks' gestation received betamethasone plus TRH (4 doses of 400 micrograms 8-hourly) or betamethasone plus placebo.