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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 109 records · Page 6Linked to original sources
PubMed1996

Effect of maternal age and parity on the risk of uteroplacental bleeding disorders in pregnancy.

OBJECTIVE: To examine the risk of placental abruption, placenta previa, and uterine bleeding of unknown etiology in relation to advanced maternal age and parity in a large, population-based study. METHODS: Data for this study were derived from the Nova Scotia Atlee perinatal provincial data base, Canada, an ongoing project on human reproduction. Women who delivered between 1980 and 1993 (n = 123,941) in the province of Nova Scotia were included in the study, with the exception of pregnancies resulting in multiple births (n = 2859) and those missing data on maternal age or parity (n = 14). Multivariable logistic regression models based on the method of generalized estimating equations were used to generate odds ratios after adjustment for multiple confounders. RESULTS: The frequency of abruption was increased slightly among younger women (relative risk [RR] 1.3, 95% confidence interval [CI] 1.0-1.7), compared with women ages 25-29 years, but there was no increase with advancing maternal age. In contrast, the risk of placenta previa increased dramatically with advancing maternal age, with women older than 40 years having a nearly ninefold greater risk than women under the age of 20, after adjustment for potential confounders, including parity. Uterine bleeding of unknown etiology was not associated with advanced maternal age, except for a slight increase among women over 40 (RR 1.3, 95% CI 1.0-1.6). The risk of placenta previa and placental abruption was increased with higher parity among younger women only, but uterine bleeding of unknown etiology was more weakly associated with higher parity. In addition, an analysis of the joint effects of age and parity on placental abruption indicated a strong parity effect for women under 30 years, whereas the risk of placenta previa increased with increasing parity up to age 35 years. Uterine bleeding of unknown etiology also indicated a parity effect that was restricted to women under 25 years. CONCLUSION: Multiparity is associated with the risk of placenta previa and, to a lesser extent, placental abruption, but not with other uterine bleeding. Increasing maternal age is associated independently with the risk of placenta previa, but not with either of the other two conditions. Finally, the increased risks of uteroplacental bleeding disorders with advanced parity among the younger women (ie, 20-25 years, parity 3+) may reflect effects of close pregnancy spacing, or confounding by unmeasured factors that characterize women who have many pregnancies at a relatively young age. Overall, the findings suggest that the three uteroplacental bleeding disorders do not share a common etiology in relation to maternal age and parity, and that placenta previa is linked to aging of the uterus and the effects of repeated pregnancies.

Abruptio Placentae↗
PubMed1996

Race, age, and cesarean delivery in a military population.

OBJECTIVE: To evaluate the relationship between race, age, and the risk of cesarean delivery. METHODS: This was a cohort study of 3603 nulliparous enlisted United States Navy women who were on active duty and had a singleton delivery between October 1987 and September 1989. Type of delivery and complications of pregnancy, labor, or delivery were identified through hospital discharge diagnoses codes. Demographic risk factors were obtained from military personnel files. RESULTS: Women over age 30 had a significantly increased risk of cesarean delivery (odds ratio [OR] 1.4, 95% confidence interval [CI] 1.1-1.9) compared with women under age 30. Multiple logistic regression modeling adjusted for education, marital status, military rank, type of hospital, and complications of pregnancy, labor and delivery showed African-American women over age 30 to have a significantly increased risk for cesarean delivery (OR 2.2, 95% CI 1.1-4.2) compared with white women over age 30. Among women under 30, African-Americans were not at a greater risk of cesarean delivery (OR 1.1; 95% CI 0.89-1.3). Other demographic factors were not related to the risk of cesarean delivery, but complications of pregnancy, labor, and delivery were strong predictors. CONCLUSION: We observed an increased risk in this unique population over age 30. Active duty military women serve as a useful population to examine demographic differences because of equitable access to medical care.

Adult↗
PubMed1996

Exercise during pregnancy among US women.

This report describes the prevalence and pattern of exercise during pregnancy among US women. It is based on 9953 randomly selected women who gave birth to live infants in 1988 and participated in the National Maternal and Infant Health Survey, a cross-sectional survey with a stratified systematic sampling in 48 states, the District of Columbia, and New York City. Self-reported exercise before and during pregnancy, specific activities, and number of months of exercise were examined in relation to maternal demographic characteristics, reproductive history, and prenatal care. Forty-two percent of all women reported exercising during pregnancy, half of whom exercised longer than 6 months. Walking was the leading activity (43% of all activities reported), followed by swimming (12%) and aerobics (12%). Older mothers and women who had multiple gestations, previous children, or an unfavorable reproductive history were less likely to exercise during pregnancy. Given this high prevalence of exercise in pregnancy, more research is warranted on both the beneficial and adverse maternal and fetal effects of exercise in pregnancy.

Adolescent↗
PubMed1996

Estimating exposure in studies of residential magnetic fields and cancer: importance of short-term variability, time interval between diagnosis and measurement, and distance to power line.

Validity of exposure assessment methods has been a major concern in epidemiologic studies of magnetic field exposure and cancer. We conducted a study to evaluate the relative importance of distance to power lines and calculated historical magnetic fields when estimating past magnetic field exposure. Another goal was to compare results based on various estimates of magnetic field exposure, to assess the importance of short-term variability in magnetic fields, time between diagnosis and measurement, and sources of magnetic field exposure. We used data from a Swedish case-control study of residential exposure to magnetic fields and cancer. Childhood leukemia risk was associated with calculated historical annual average magnetic fields regardless of distance, and the association with distance disappeared when both variables were entered into the same logistic regression model. Relative risks for measurements at the time of the study (contemporary annual average fields, spot calculations, and spot measurements) were all close to or below unity. The results support the hypothesis that the difference between results using historical calculations and spot measurements is explained by the time interval between diagnosis and contemporary magnetic field estimates.

Adolescent↗
PubMed1996

Maternal occupation and pregnancy outcome.

Few studies have addressed the effect of maternal employment on late pregnancy outcomes. The National Maternal and Infant Health Survey, a probability sample of U.S. livebirths, stillbirths, and infant deaths in 1988, provided an opportunity to evaluate mothers' jobs in relation to preterm delivery, very low birthweight ( < 1,500 gm), moderately low birthweight (1,500-2,499 gm), small-for-gestational-age (SGA) birth, stillbirth, and infant death. We aggregated mothers' jobs, which were ascertained by mailed questionnaire or telephone interview, into categories for analysis. We considered jobs held at any time during pregnancy and jobs held during the fifth month of pregnancy. Relative to the referent group of clerks, textile workers had adjusted odds ratios of 1.5 or greater for all outcomes, with elevated risks also found sporadically for food service workers (preterm delivery, SGA birth, stillbirth) and electrical equipment operators (all outcomes except for still-birth and infant death). Janitors had elevated adjusted odds ratios of 2.0 or greater for preterm delivery and stillbirth. Relative to clerks, teachers and librarians tended to have reduced risks for adverse outcomes.

Adolescent↗
PubMed1996

The effect of maternal drinking before conception and in early pregnancy on infant birthweight. The ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood.

We examined the association of maternal drinking before and during early pregnancy on infant birthweight, using data collected from a population-based cohort in Avon Country, England. Participants completed several self-administered questionnaires during their index pregnancy. Our analysis included 10,539 women who provided drinking data and delivered a liveborn singleton child. Infants born to women who reported drinking one to two drinks daily with at least one binge, or three or more drinks daily with or without binges, had an adjusted mean birthweight approximately 150 gm less than that of infants whose mothers reported abstaining during (but not before) pregnancy. Mean birthweights were similar for infants of prepregnancy drinkers who drank weekly in early pregnancy, less than weekly, or not at all.

Alcohol Drinking↗
PubMed1996

Menstrual and reproductive history of mothers of galactosemic children.

OBJECTIVE: To test the hypothesis that female carriers of the galactosemia gene (mothers of galactosemic children) experience impaired fecundability and earlier age at natural menopause. DESIGN: Retrospective cohort study comparing experiences of mothers of galactosemic children with mothers of children with phenylketonuria (PKU). Data collection consisted of a structured telephone interview with sections on menstrual, reproductive, and medical histories. PARTICIPANTS: One hundred three galactosemia carriers and 116 PKU carriers (mean age 35.0 and 38.4 years, respectively), recruited from 38 metabolic disease clinics throughout the United States. MAIN OUTCOME MEASURES: Time-to-pregnancy (a measure of fecundability), menstrual cycle patterns, and natural menopause. RESULTS: No difference was seen between carriers of the galactosemia and the PKU gene in history of > or = 12 months of unprotected intercourse without a pregnancy, physician-diagnosed infertility, or amenorrhea lasting > 6 weeks. The fecundability ratio, adjusting for age and smoking before most recent pregnancy, was 1.17 (95% confidence interval [CI] 0.85 to 1.61). By age 45, 11% of galactosemia carriers who had not had a hysterectomy reported a natural menopause compared with 4% of PKU carriers (risk difference 7.2%, 95% CI -12.7% to 27.1%). CONCLUSION: Fecundability and other measures of fertility did not differ between mothers of galactosemic children and mothers of children with PKU. Suggestions of an earlier age at natural menopause can not be addressed definitively in this cohort because of the small number of participants who were currently age 45 years or older but may warrant additional assessment as the cohort ages.

Adult↗
PubMed1995

Recall accuracy for prescription medications: self-report compared with database information.

A methodological study was performed in 1992 to evaluate the accuracy of self-reported use of nonsteroidal antiinflammatory drugs (NSAIDs) and noncontraceptive estrogens that had been dispensed during the previous 12 years. A sample of 560 individuals dispensed NSAIDs or estrogens, and 140 individuals without NSAID/estrogen dispensations were selected from the Group Health Cooperative pharmacy database. Demographic, behavioral, and drug information was ascertained by telephone interview for 356 persons with and 98 persons without NSAID/estrogen dispensations. Of those with only a single NSAID dispensation, 41% (95% confidence interval (CI) 32-50%) were able to recall any NSAID use compared with 85% (95% CI 76-94%) for those with multiple NSAID dispensations. Thirty percent (95% CI 24-36%) recalled the NSAID name, and 15% (95% CI 10-20%) recalled both the name and dose. For estrogens, 78% (95% CI 70-86%) recalled the name, but only 26% (95% CI 17-34%) recalled the name and dose. Age, but not sex, appeared to influence recall accuracy: Persons 50-65 years of age recalled the NSAID name more accurately than those aged 66-80 (odds ratio (OR) = 1.8, 95% confidence interval (CI) 1.0-3.4). A similar advantage was noted for 50- to 65-year-old women in recalling the estrogen name (OR = 1.5, 95% CI 0.6-3.9). Drug name was recalled more frequently for exposures stopped 2-3 years prior to interview than for those stopped 7-11 years prior (OR = 3.0, 95% CI 1.6-5.7, and OR = 2.4, 95% CI 0.9-6.7, for NSAIDs and estrogens, respectively). Specificity was consistently high, ranging from 92% to 100%. This study suggests significant underascertainment of self-reported prescription drug exposure but little evidence that exposures are overreported.

Aged↗
PubMed1995

Exposure assessment strategies in epidemiological studies of health effects of electric and magnetic fields.

In the growing epidemiological literature on potential health effects of electric and magnetic fields in homes, from appliances, and in the workplace, exposure assessment persists as the principal challenge. Associations of concern are residential exposure and childhood cancers, occupational exposure and adult leukemia and brain cancer, and video display terminal use and pregnancy outcome. The biologically appropriate measure of exposure is undefined, there are a multitude of exposure sources, and because the concern is with such rare diseases as leukemia and brain cancer, all studies have retrospective exposure ascertainment. Residential exposure assessment has been based on wire configuration codes of nearby electric power lines or on in-home measurements, both proxies for historical exposures of interest. Each has theoretical and logistical advantages and disadvantages. Appliance exposures are based on self-report, focusing on those used for prolonged periods in close proximity to the user, such as electric blankets. Workplace exposures have been assessed by job title, more recently supplemented with measurements. Research is needed to: (1) develop and validate historical exposure models; (2) find ways to integrate exposure across diverse sources in the home and workplace; and (3) exploit laboratory findings to guide the selection of exposure metrics and relevant time windows.

Adult↗
PubMed1995

Validity of mother's report of father's occupation in a study of paternal occupation and congenital malformations.

Agreement between the mother's and father's report of the father's occupation was assessed in a case-control study of paternal occupation and birth defects. Cases were identified from births registered with the Metropolitan Atlanta Congenital Defects Program between 1968 and 1980; controls were selected from liveborn infants without defects. Both parents were sought for interview, and each parent was asked about the father's job history for 2 years prior to the infant's death. This concordance analysis is based on 3,739 case infants and 2,279 control infants for whom both parents were interviewed. The authors considered the father's report of his occupation as correct, and they assessed the ability of the mother to report the same occupation(s) during a 7-month period around conception. The exact agreement between mother's and father's report of the father's occupation was 59%. Agreement improved slightly with increasing family income and when fathers were college graduates. Female partners were not accurate proxy respondents in this study of paternal occupation and birth defects, which suggests that investigators should interview both parents in studies of paternal exposures and reproductive outcomes, i.e., mothers for pregnancy history and maternal confounders and fathers for occupational history and paternal confounders.

Case-Control Studies↗
PubMed1995

Nitrous oxide and spontaneous abortion in female dental assistants.

The relation between anesthetic gas exposure and spontaneous abortion remains unresolved. We examined the effect of nitrous oxide on spontaneous abortion among female dental assistants. Questionnaires were sent to 7,000 dental assistants aged 18-39 years who were registered in California in 1987; 4,856 (69%) responded. Analysis was based on 1,465 respondents whose most recent pregnancy was conceived while working full time. Women were asked how many hours a week they worked with nitrous oxide during this pregnancy and whether the excess gas was scavenged (vented). Relative risk of spontaneous abortion (through week 20) was calculated using a person-week model. This allowed women with current pregnancies (13%) or induced abortions (10%) to be included for appropriate time periods of risk. A total of 101 pregnancies (7%) ended as spontaneous abortions. An elevation in risk of spontaneous abortion was seen among women who worked with nitrous oxide for 3 or more hours per week in offices not using scavenging equipment (relative risk = 2.6, 95% confidence interval 1.3-5.0, adjusted for age, smoking, and number of amalgams prepared per week), but not among those using nitrous oxide in offices with scavenging equipment. This relation changed little when analyses were restricted to confirmed pregnancies or examined for several types of potential bias. Scavenging equipment appears to be important in protecting the reproductive health of women working with nitrous oxide.

Abortion, Spontaneous↗
PubMed1995

Magnetic field exposure in relation to leukemia and brain cancer mortality among electric utility workers.

Reports of leukemia and brain cancer among men in electrical occupations suggest a small increase in risk, but most previous studies have failed to classify magnetic field exposure accurately or to consider potential confounders. The authors conducted an historical cohort mortality study of 138,905 men employed at five large electric power companies in the United States between 1950 and 1986 with at least 6 months of work experience. Exposure was estimated by linking individual work histories to data from 2,842 workshift magnetic field measurements. Mortality follow-up identified 20,733 deaths based on 2,656,436 person-years of experience. Death rates were analyzed in relation to magnetic field exposure history with Poisson regression. Total mortality and cancer mortality rose slightly with increasing magnetic field exposure. Leukemia mortality, however, was not associated with indices of magnetic field exposure except for work as an electrician. Brain cancer mortality was modestly elevated in relation to duration of work in exposed jobs and much more strongly associated with magnetic field exposure indices. Brain cancer risk increased by an estimated factor of 1.94 per microtesla-year of magnetic field exposure in the previous 2-10 years, with a mortality rate ratio of 2.6 in the highest exposure category. In contrast to other studies, these data do not support an association between occupational magnetic field exposure and leukemia but do suggest a link to brain cancer.

Aged↗
PubMed1995

Case-control study of caffeinated beverages and preterm delivery.

Although many women reduce their caffeine consumption once they known they are pregnant, 70-80% of pregnant women still consume caffeine. To evaluate the relation between caffeine consumption and preterm delivery, a case-control study was conducted to identify all preterm (< 37 weeks gestation) infants born to women in selected North Carolina counties from September 1988 through April 1991. Randomly selected full-term, normal-weight livebirths (matched by race and hospital) served as controls. The study population consisted of 408 cases and 490 controls. Telephone interviews with participants assessed the consumption of caffeinated coffee, tea, cola soft drinks, and noncola caffeinated soft drinks, with caffeine consumption measured by the number of daily servings of each beverage and the total milligrams of caffeine. Third-trimester caffeine consumption from all beverages combined showed a nonsignificant inverse association with preterm delivery. Both first- and second-trimester consumption of 1-150 mg/day were associated with a modestly increased risk of preterm delivery, while no association was found at higher consumption levels. Overall, these results do not support an association between caffeinated beverage consumption and preterm delivery, as is true in most previous studies.

Adult↗
PubMed1995

Childhood cancer in relation to indicators of magnetic fields from ground current sources.

This study examines childhood cancer risk in relation to certain factors likely to indicate magnetic field exposure from ground currents in the home. Substantial ground currents are most often found in homes having conductive plumbing, in which an uninterrupted metallic path in the water pipes and water main connects the grounding systems of neighboring houses. Information on plumbing conductivity was obtained from water suppliers for the homes of 347 cases and 277 controls identified in an earlier study of magnetic field exposure and childhood cancer in the Denver area. An increased cancer risk was observed for children in homes with conductive plumbing: The matched odds ratio was 1.72 (1.03-2.88) and increased to 3.00 (1.33-6.76) when analysis was limited to cases and controls who were residentially stable from the reference date to the study date. A measurement metric likely to indicate active ground currents (measurements having above-median intensity and a nonvertical orientation of < 55 degrees from the horizontal) was identified. In contrast to measured field intensity alone, for which only modest associations with cancer have been reported, this metric shows a high and significant cancer risk [matched O.R. = 4.0 (1.6-10.0)] consistent over a range of intensity and angle cutpoints. Such elevated nonvertical fields were also associated with cancer in an independent data set, which was gathered to study adult nonlymphocytic leukemia in the Seattle area. The associations of cancer with conductive plumbing and with this exposure metric both suggest that cancer risk is increased among persons with elevated magnetic field exposure from residential ground currents.

Adolescent↗
PubMed1995

Follicle-stimulating hormone concentrations in relation to active and passive smoking.

OBJECTIVE: To determine the association between various forms of tobacco exposure and ovarian status, as measured by FSH concentrations, in women 38-49 years old. METHODS: Two hundred ninety women between 38-49 years old, who had not had hysterectomy or oophorectomy, completed a self-administered questionnaire that included information on tobacco exposure and had serum FSH levels measured on days 2-4 of the menstrual cycle. Linear regression was used to assess the relation between FSH and tobacco exposure. RESULTS: Controlling for age and other factors, FSH concentrations were 66% higher among current smokers (geometric mean FSH 14.0 mIU/mL) and 39% higher among nonsmokers with passive smoke exposure (11.7 mIU/mL), compared to nonsmoking women without passive smoke exposure (8.4 mIU/mL). The estimated increase in FSH for each year of age was greater for current smokers than for nonsmokers (16 versus 6%, respectively). Ex-smokers did not have higher FSH concentrations, and there was no association between prenatal exposure to tobacco smoke and FSH. CONCLUSION: Both active and passive smoking are associated with elevated FSH concentrations in women 38-49 years old. The effect, limited to women with current exposure, is consistent with a shorter duration of the menopausal transition period.

Adult↗