Biomedical subjects

S Selvin

Publications and source records attributed to S Selvin.

At least 19 recordsLinked to original sources

PubMed2002

Daycare attendance and risk of childhood acute lymphoblastic leukaemia.

The relationship between daycare/preschool ("daycare") attendance and the risk of acute lymphoblastic leukaemia was evaluated in the Northern California Childhood Leukaemia Study. Incident cases (age 1-14 years) were rapidly ascertained during 1995-1999. Population-based controls were randomly selected from the California birth registry, individually matched on date of birth, gender, race, Hispanicity, and residence, resulting in a total of 140 case-controls pairs. Fewer cases (n=92, 66%) attended daycare than controls (n=103, 74%). Children who had more total child-hours had a significantly reduced risk of ALL. The odds ratio associated with each thousand child-hours was 0.991 (95% confidence interval (CI): 0.984-0.999), which means that a child with 50 thousand child-hours (who may have, for example, attended a daycare with 15 other children, 25 h per week, for a total duration of 30.65 months) would have an odds ratio of (0.991)(50)=0.64 (95% CI: 0.45, 0.95), compared to children who never attended daycare. Besides, controls started daycare at a younger age, attended daycare for longer duration, remained in daycare for more hours, and were exposed to more children at each daycare. These findings support the hypothesis that delayed exposure to common infections plays an important role in the aetiology of childhood acute lymphoblastic leukaemia, and suggest that extensive contact with other children in a daycare setting is associated with a reduced risk of acute lymphoblastic leukaemia.

Adolescent↗

PubMed2001

Does the pattern of postpartum weight change differ according to pregravid body size?

OBJECTIVES: To examine differences in the pattern of weight changes during and after pregnancy among four pregravid body mass index (BMI) groups. STUDY DESIGN: Prospective cohort study of women who had two consecutive births at the University of California, San Francisco (UCSF) between 1980 and 1990. MEASUREMENTS: Maternal body weights were available before conception and delivery, and at 6 weeks postpartum for the first (index) pregnancy, and before conception for the second study pregnancy. Height and two pregravid weights were self-reported. Weights at delivery and 6 weeks postpartum were measured. Net delivery weight was defined as delivery weight minus infant birth weight. Three non-overlapping sequential weight changes were constructed: (1) net gestational gain (net delivery weight minus pregravid weight at the index pregnancy); (2) early net postpartum weight change (6-week postpartum weight minus net delivery weight); and (3) late postpartum weight change (pregravid weight at the second pregnancy minus 6-week postpartum weight). SUBJECTS: A total of 985 healthy women (age 18-41 y) from four race/ethnicity groups (Asian, Hispanic, black and white) who had a singleton, full-term, live birth for the index pregnancy followed by a second consecutive birth. RESULTS: Four race/ethnicity groups were combined (no interaction) to contrast average weight changes among pregravid BMI groups. Means adjusted for eight covariates (parity, race/ethnicity, education, mode of delivery, smoking, hypertension of pregnancy, age, height) and time intervals were not altered appreciably. Early net postpartum weight losses were similar for all pregravid BMI groups. Late (median of 2 y) postpartum weight losses were 4 kg higher in the low and average BMI groups compared with the highest BMI group. About half of the net gestational gain was lost by 6 weeks postpartum, and the percentage that was lost decreased over time. CONCLUSIONS: This study suggests that early postpartum weight loss does not vary by maternal pregravid BMI group, but late postpartum weight change does. Serial weight measurements are needed in epidemiologic studies to differentiate retention of gestational gain from weight gain during the late postpartum period.

Adolescent↗

PubMed2001

Lowered weight gain during pregnancy and risk of neural tube defects among offspring.

BACKGROUND: Maternal nutritional factors have been implicated in the complex aetiology of neural tube defects (NTD). We investigated whether the amount of weight a woman gained during pregnancy was associated with her risk of delivering an infant with an NTD. METHODS: We conducted a population-based case-control study within the cohort of 708 129 live births and fetal deaths occurring in selected California counties in 1989-1991. Face-to-face interviews were conducted with mothers of 538 (88% of eligible) NTD cases (including those electively terminated, stillborn, or liveborn) and with mothers of 539 (88%) non-malformed liveborn controls within an average of 5 months from the term delivery date. Respondent-reported weight gain during pregnancy (kg) was analysed. Risks of infants having NTD were estimated among women who gained <10 kg compared to those who gained > or =10 kg during > or =38 week gestations. RESULTS: Compared to women who gained > or =10 kg, an increased risk for NTD offspring was observed among women who gained <10 kg (odds ratio [OR] = 3.2, 95% CI : 2.3-4.6). The OR was 5.0 (95% CI : 2.6-9.7) among those women who gained <5 kg during pregnancy. The increased risk was not attributable to maternal non-use of a multivitamin containing folic acid, diabetes, NTD-pregnancy history, age, race/ethnicity, education, gravidity, alcohol use, cigarette use, prepregnant obesity, low socioeconomic status, dieting, nausea, nor to lower dietary intakes of folate, zinc, energy, protein, fat, carbohydrates, and methionine. An increased risk was observed even after simultaneous adjustment for most of these factors (OR = 2.2, 95% CI : 1.2-3.8). The risk associated with gaining <10 kg was greater for anencephaly, but still elevated for spina bifida. CONCLUSIONS: We did not have information on weight gain during early pregnancy. Because weight gain during the relevant embryological period for NTD (first month post-conception) is relatively small and often variable, it seems less likely that elevated NTD risks indicate a causal association between lowered weight gain throughout pregnancy and abnormal development of the neural tube. It seems more likely that lowered weight gain is a consequence of carrying an NTD-affected fetus. However, what this consequence is and why risk was substantially larger for anencephaly is unknown.

Adult↗

PubMed2001

The epidemiology of mental retardation of unknown cause.

OBJECTIVE: To describe selected infant and maternal characteristics for children with mild and severe mental retardation (MR) of unknown cause. STUDY DESIGN: Children with MR of unknown cause born in California between 1987 and 1994 were identified through service agency records and compared with the total population of California live births for selected characteristics recorded on the birth certificate. RESULTS: For both children with mild and severe MR, risk was increased among males, low birth weight children, and children born to women of black race, older age at delivery, and lower level of education. Increased risk for mild MR was found for multiple births, second or later-born children, and children whose mothers were born outside of California. Increased risk for severe MR was observed among children born to Hispanic mothers; children born to Asian mothers also had increased risk for severe MR but decreased risk for mild MR. CONCLUSIONS: These results provide clues for understanding the underlying causes of MR and suggest that both biological and social factors are important.

Adolescent↗

PubMed2000

The relative importance of gestational gain and maternal characteristics associated with the risk of becoming overweight after pregnancy.

OBJECTIVES: To assess the relationships between gestational gain, race/ethnicity, reproductive history, age, education and the risk of becoming overweight after pregnancy. STUDY DESIGN: Prospective cohort study of adult women from four race/ethnicity groups who had two consecutive births between 1980 and 1990 at the University of California, San Francisco (UCSF). MEASUREMENTS: Height and pregravid weights for each pregnancy were self-reported. Women were classified as overweight or not overweight according to the Institute of Medicine (IOM) criteria for pregnancy. Gestational gain was defined as the difference between the pregravid weight and the last weight before delivery of the first study pregnancy. SUBJECTS: 1300 healthy women aged 18-41 y who had a singleton, full-term, live birth (index or first study pregnancy) followed by a second birth. Self-reported pregravid weights and heights were used to calculate body mass index (BMI). Women with a pregravid BMI below 26.0 kg/m2 before the index pregnancy were classified as not overweight (n = 1128). Overweight status following the index pregnancy was based on pregravid BMI for the second pregnancy. RESULTS: Seventy-two women (6.4%) became overweight following the index pregnancy. Statistically significant independent predictors of the risk of becoming overweight included: maternal age 24-30 vs above 30 y, high gestational gain, short interval from menarche to first ever birth ( < 8 y), and young age at menarche ( < 12 y). The risk of becoming overweight was increased 2.5-3 times for each of these risk factors. Whites were 4.5 times more likely to become overweight than Asians, but blacks and Hispanics did not appear to differ from whites. Parity, time interval, smoking habit, education, marital status and other factors were not associated with the risk of becoming overweight. CONCLUSIONS: These findings suggest that young age at menarche, maternal age and short time from menarche to first ever birth may be as important as high gestational weight gain in determining the risk of becoming overweight after pregnancy.

Adolescent↗

PubMed2000

Maternal height and prepregnancy body mass index as risk factors for selected congenital anomalies.

Previous studies have observed an increased risk of approximately twofold or more for neural tube defects (NTD) associated with maternal obesity before pregnancy based on a body mass index (BMI) of > 29 kg/m2. No additional maternal factor appeared substantially to influence this association. Here, we explore further the association between BMI and NTD risk by considering the separate contributions of maternal prepregnant BMI and height. We also explore whether selected congenital anomalies, in addition to NTDs, were associated with maternal height or prepregnant BMI. Data were derived from two California population-based case-control studies. One study comprised 538 NTD cases and 539 non-malformed control infants. The other study included an additional 265 NTD cases, as well as 207 conotruncal cases, 165 limb anomaly cases, 662 orofacial cleft cases and 734 non-malformed controls. Maternal interviews in both studies elicited information on maternal height and prepregnant weight. Anomaly risk was described using additive linear logistic regression models. Results revealed increasing NTD risk with increasing maternal prepregnant BMI, controlling for maternal height. These patterns were observed overall as well as for most race/ethnic groups. Increasing NTD risk for decreasing height controlling for maternal BMI was also observed in one NTD study, but was not as evident in the other. Elevated risks for increasing maternal BMI and decreasing maternal height were not observed consistently for the other studied anomalies. The mechanisms underlying the association between maternal weight, or possibly maternal height, and NTD-affected pregnancy risk are unknown. Exploration of other data sets will be needed to determine whether similar patterns of NTD risk or lack of risk for other anomalies are associated with the two maternal anthropometric variables, height and prepregnant weight.

Body Height↗

PubMed2000

Defining preterm delivery--the epidemiology of clinical presentation.

It is possible that preterm delivery is not a single entity but a cluster of conditions with different aetiologies that ultimately result in the delivery of an infant before 37 completed weeks of gestation. Whereas some researchers have reported aetiological heterogeneity, others have found no differences between subtypes or have disputed the desirability and utility of classifying preterm birth into subtypes. This study explores the relationship of maternal risk factors to type of preterm delivery in a cohort of over 7000 black and white women delivering singleton infants at the University of California, San Francisco's Moffitt Hospital between 1980 and 1990. Although the magnitude of the effect of individual risk factors differed between preterm delivery subtypes, the set of risk factors significantly associated with both categories of spontaneous preterm delivery was identical, while that associated with medically indicated preterm births was different. This study indicates that whereas the distinction between spontaneous preterm deliveries and those that are medically indicated seems valid, distinguishing between types of spontaneous preterm births may not lead to useful aetiological inferences.

Adolescent↗

PubMed2000

Prevalence of gynecologic cancers among female Vietnam veterans.

The possibility of a gender-specific health problem associated with the Vietnam War has been a concern since the war. We targeted 4140 female Vietnam veterans and 4140 veteran controls to complete a structured telephone interview that included questions regarding any history of gynecologic cancer. As a measure of association between the risk of cancer and military service in Vietnam, odds ratios and 95% confidence intervals were calculated using multiple logistic regression models that yielded estimates of potential cofounders. Although 8% of Vietnam veterans and 7.1% of non-Vietnam veterans reported a history of gynecologic cancers, namely, breast, ovary, uterus, or cervix, the difference was not statistically significant either for the individual site or for the gynecologic cancers as a group. Female Vietnam veterans have not experienced a higher prevalence of gynecologic cancer in the 30 years since the conflict.

Adult↗

PubMed1999

Periconceptional nutrient intake and risk for neural tube defect-affected pregnancies.

We investigated whether intakes of nutrients, including folate, by women in the periconceptional period were associated with risks of neural tube defect (NTD)-affected pregnancies. Data were part of a case-control study of fetuses and infants with NTDs among 1989-1991 California births. We conducted interviews with mothers of 409 NTD cases and 420 nonmal-formed controls. Nutrient intake for the 3 months before conception was derived from food frequency questionnaires and from questions to mothers about vitamin/mineral supplement use. We computed NTD risk for each nutrient controlling for the influence of all other studied nutrients and for maternal education, race/ethnicity, height, and prepregnancy weight. Most single nutrients reduced NTD risks when intakes were considered in quartiles and unadjusted for other nutrients. Some of the same nutrients, however, did not provide similar interpretations when we adjusted for other nutrients. Adjusted analyses revealed decreased NTD risks with increased intakes of methionine, lutein, magnesium, zinc, and thiamin for women who did not use vitamin supplements periconceptionally. We observed decreased NTD risks associated with increased intakes of linoleic acid, cysteine, calcium, and zinc for women who used supplements. We also observed increased NTD risks with increased intakes of oleic acid. For users as well as nonusers of vitamin supplements, we observed reduced risks with increased intakes of grains and dairy products. Chance was a likely alternative explanation for many of the observed risk patterns.

California↗

PubMed1998

Magnesium sulfate tocolysis and risk of neonatal death.

OBJECTIVE: Our purpose was to evaluate the association between in utero exposure to magnesium sulfate and neonatal death. STUDY DESIGN: Case-control comparison was performed of singleton infants who died at 0 to 28 days and control infants who survived to age 3 years and did not have disabling cerebral palsy. All subjects were born between 1983 and 1985 to mothers resident in one of four northern California counties. RESULTS: Magnesium sulfate tocolysis was associated with a decreased risk of neonatal mortality (odds ratio 0.25, 95% confidence interval 0.6 to 1.1). Adjustment for birth weight and gestational age increased the inverse association (odds ratio 0.09, 95% confidence interval 0.01 to 0.93). The association between neonatal mortality and magnesium sulfate was not altered by maternal infection, gender, maternal race or ethnicity, maternal age, level of care, breech presentation, surgical delivery, corticosteroids, abruptio placentae, placenta previa, or bleeding on admission. CONCLUSIONS: Magnesium sulfate tocolysis was not associated with increased neonatal mortality in premature infants. Thus any association of magnesium with reduced long-term neurologic morbidity is unlikely to be the result of selective mortality of vulnerable infants.

Birth Weight↗

PubMed1998

The burden, trends, and demographics of mortality from subarachnoid hemorrhage.

OBJECTIVE: The objective of this study was to describe the recent epidemiology of mortality from subarachnoid hemorrhage in the United States. BACKGROUND: Subarachnoid hemorrhage is distinct from other forms of stroke in its risk factors, demographics, and treatment. However, it is often clustered with other stroke subtypes, obscuring its unique epidemiology. METHODS: We analyzed subarachnoid hemorrhage mortality data from the National Center for Health Statistics of the United States for the years 1979 to 1994 and compared it with other stroke subtypes. RESULTS: Age-adjusted mortality rates of subarachnoid hemorrhage were 62% greater in females than in males and 57% greater in blacks than in whites. The median age of death from subarachnoid hemorrhage was 59 years compared with 73 years for intracerebral hemorrhage and 81 years for ischemic stroke. Mortality rates of subarachnoid hemorrhage have decreased by approximately 1% per year since 1979, and the mean age of death has steadily increased from 57 years in 1979 to 60 years in 1994. Subarachnoid hemorrhage accounted for 4.4% of stroke mortality but 27.3% of all stroke-related years of potential life lost before age 65, a measure of premature mortality. The proportion of years of potential life lost due to subarachnoid hemorrhage was comparable with ischemic stroke (38.5%) and intracranial hemorrhage (34.2%). CONCLUSIONS: Subarachnoid hemorrhage is an uncommon cause of stroke mortality but occurs at a young age, producing a relatively large burden of premature mortality, comparable with ischemic stroke.

Adult↗

PubMed1998

Socioeconomic status, neighborhood social conditions, and neural tube defects.

OBJECTIVES: This study evaluated the contributions of lower socioeconomic status (SES) and neighborhood socioeconomic characteristics to neural tube defect etiology. The influence of additional factors, including periconceptional multivitamin use and race/ethnicity, was also explored. METHODS: Data derived from a case-control study of California pregnancies from 1989 to 1991. Mothers of 538 (87.8% of eligible) case infants/fetuses with neural tube defects and mothers of 539 (88.2%) nonmalformed infants were interviewed about their SES. Reported addresses were linked to 1990 US census information to characterize neighborhoods. RESULTS: Twofold elevated risks were observed for several SES indicators. Risks were somewhat confounded by vitamin use, race/ethnicity, age, body mass index, and fever but remained elevated after adjustment. A risk gradient was seen with increasing number of lower SES indicators. Women with 1 to 3 and 4 to 6 lower SES indicators had adjusted odds ratios of 1.6 (1.1-2.2) and 3.2 (1.9-5.4), respectively, compared with women with no lower SES indicators. CONCLUSIONS: Both lower SES and residence in a SES-lower neighborhood increased the risk of an neural tube defect-affected pregnancy, with risks increasing across a gradient of SES indicators.

Adult↗

PubMed1998

Breast cancer detection: maps of 2 San Francisco Bay area counties.

OBJECTIVES: This study describes the incidence of late-stage and in situ breast cancer among White women, using specialized mapping techniques that reflect incidence adjusted for the population at risk, and applies these maps to characterize areas with high and low risk of breast cancer. METHODS: Data from the Surveillance, Epidemiology, and End Results (SEER) database and the US Census Bureau were used to study the geographic distribution of breast cancer at the census-tract level in 2 San Francisco Bay Area counties for the years 1978 through 1982. Sociodemographic characteristics of areas with high and low incidence of the stage-specific disease were compared by means of a linear discriminant function. RESULTS: For late-stage breast cancer, the most important variables in discriminating high-risk from low-risk areas were college education, percentage of residents over age 65, and median income. The strongest ecologic indicators of high risk for in situ breast cancer were median income and percentage unemployed. CONCLUSIONS: This study demonstrates the usefulness of census tracts and sociodemographic measures of income and education in describing in situ and late-stage breast cancer.

Adolescent↗

PubMed1997

Physical workload and ergonomic factors associated with prevalence of back and neck pain in urban transit operators.

STUDY DESIGN: Back and neck pain was studied cross-sectionally in 1,449 urban transit drivers by linking medical data, self-reported ergonomic factors, and company records on job history. OBJECTIVES: The goal was to examine the relation between physical workload, ergonomic factors, and the prevalence of back and neck pain. SUMMARY OF BACKGROUND DATA: Researchers, to date, have not found an independent effect of ergonomic factors on back and neck pain while accounting for the effects of past and current physical workload. METHODS: Self-reported ergonomic factors, vehicle type, physical workload (measured as duration of driving), height, weight, age, and gender were analyzed in relation to back and neck pain, using multivariable logistic regression models. RESULTS: Physical workload showed a positive dose-response relation with back and neck pain after controlling for vehicle type, height, weight, age, and gender. The odds ratio for 10 years of driving was 3.43. Additional adjustment for ergonomic factors decreased this odds ratio to 2.55. Six out of seven ergonomic factors were significantly related to the prevalence of back and neck pain after adjustment for age, gender, height, weight, and physical workload. Problems with adjusting the seat had the largest effect (odds ratio = 3.52). Women had back and neck pain twice as frequently as men. CONCLUSION: The results support the hypothesis of a causal role of physical workload for the development of back and neck pain. Ergonomic factors partially mediated the risk of back and neck pain associated with driving, suggesting a potential for prevention of back and neck pain by ergonomic redesign of transit vehicles. Elevated risks for back and neck pain for female drivers were not explained by anthropometric and ergonomic factors.

Adult↗

PubMed1997

The association of pattern of maternal weight gain with length of gestation and risk of spontaneous preterm delivery.

Monitoring weight gain during pregnancy may be useful in detecting pregnancies that are at increased risk of early delivery. This study examines 7259 deliveries that occurred at the University of California, San Francisco's Moffitt Hospital from 1980 to 1990. Obese women, women with diabetes or hypertension during pregnancy, deliveries with congenital malformations and non-spontaneous preterm deliveries were excluded. Pattern of gain was assessed by fitting a quadratic curve to each woman's series of weight and date measurements, using simple regression techniques. The parameters from this curve were used to develop a variable for pattern of gain that reflects how much an individual's pattern of gain differs from a linear pattern of gain. Multivariable linear and logistic regression analyses indicate that patterns of gain that deviate greatly from the average pattern of gain (i.e. patterns that show a marked speeding up or slowing down of gain towards the end of pregnancy) are associated with significantly shorter gestational age and confer a significantly increased risk of spontaneous preterm delivery. The results suggest that monitoring weight gain during pregnancy is important, although more specific studies are needed to understand the mechanisms by which weight gain pattern relates to preterm delivery before appropriate interventions can be developed.

Adult↗

PubMed1997

Maternal residential proximity to hazardous waste sites and risk for selected congenital malformations.

Using data from two population-based case-control studies, we investigated whether maternal residential proximity to hazardous waste sites increased the risk for neural tube defects, conotruncal heart defects, and oral cleft defects in California. We obtained a residential history by interview for mothers of 507 neural tube defect cases (82.7% of eligible) and their 517 controls (84.6%); and 201 heart cases (84.4%), 439 cleft cases (82.2%), and their 455 controls (72.1%). We identified the locations of 764 inactive hazardous waste sites and systematically collected information on site-related contamination for the subset of 105 National Priority List sites. After controlling for several potential confounders, we found little or no increased risk for maternal residence in a census tract containing a site [odds ratio (OR) = 0.9, 95% confidence interval (CI) = 0.7-1.3 for neural tube defects; OR = 1.3, 95% CI = 0.8-2.1 for heart cases; OR = 1.2, 95% CI = 0.8-1.8 for clefts], but elevated risks for neural tube defects (OR = 2.1, 95% CI = 0.6-7.6) and heart defects (OR = 4.2, 95% CI = 0.7-26.5) for maternal residence within 1/4 mile of a National Priority List site. Furthermore, we observed elevated ORs (> or = 2.0) for neural tube defects and heart defects in association with maternal residence within 1 mile of National Priority List sites containing selected chemical contaminants. Among controls, only 0.6% and 4.4% lived within 1/4 mile and 1 mile of a National Priority List site, respectively, resulting in imprecision in risk estimation.

Adult↗

PubMed1997

A case-control study of lung cancer among Vietnam veterans.

Because of concerns among veterans over Agent Orange exposure, the Department of Veterans Affairs (VA) has conducted a series of studies of specific cancers among Vietnam veterans. Lung cancer is the topic of investigation in this report. The VA's Patient Treatment File (PTF) was used to identify 329 Vietnam era veterans with a diagnosis of lung cancer made between 1983 and 1990. The PTF is a computerized hospitalized database of inpatient records, including patients' demographic data, and diagnoses. A record is created for each patient discharged from any one of the VA's Medical Centers. Variables abstracted from the military record include education, race, branch of service, Military Occupational Specialty Code, rank, and units served within Vietnam. Two hundred sixty-nine controls were randomly selected from the PTF file of men hospitalized for a reason other than cancer. A second control group numbering 111 patients with colon cancer was also selected from the PTF file. Data were also gathered on exposure to Agent Orange through the location of each individual ground troop veteran's unit in relation to an area sprayed and the time elapsed since that area was sprayed. The crude odds ratio between service in Vietnam and lung cancer was of borderline significance (odds ratio = 1.39 with 95% confidence interval = 1.01-1.92). The relationship disappeared when the confounder year of birth was considered. We conclude from these data that there is no evidence of increased risk in lung cancer associated with service in Vietnam at this time.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1997

The pattern of maternal weight gain in women with good pregnancy outcomes.

OBJECTIVES: This study describes the pattern of maternal weight gain in women with good pregnancy outcomes and provides data to fill in the provisional weight-gain charts published by the Institute of Medicine (IOM) in 1990. METHODS: We selected 7002 women with good outcomes (defined by factors related to maternal and infant health) from the University of California, San Francisco, Perinatal Database. For each body mass index category, we compared percentiles of weight gain by trimester in women who achieved the IOM recommendations for total gain and those who did not. RESULTS: Trimester rates of gain varied by body mass index category and exceeded IOM guidelines in all groups. Forty percent of these women with good outcomes had total gains within the guidelines and provided data to complete the IOM weight-gain charts. CONCLUSIONS: Most women in this good-outcome sample would have been suspected of being at increased risk for poor outcome on the basis of their weight gain. This confirms the IOM recommendation that evaluation of the underlying causes of excessively high or low weight gain during pregnancy is necessary before appropriate interventions can be applied.

Adult↗