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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 91 records · Page 5Linked to original sources
PubMed1997

Lymphoma and multiple myeloma mortality in relation to magnetic field exposure among electric utility workers.

Associations between occupational magnetic field exposure and non-Hodgkin's lymphoma (NHL), Hodgkin's disease, and multiple myeloma mortality were evaluated in 138,905 electrical utility workers. A job-exposure matrix based on measured magnetic fields was used to derive individual exposure estimates. There was a small positive association between all NHL and low-grade NHL and duration of employment in any magnetic field-exposed job, but only up to 20 years. Cumulative magnetic field exposure was associated with a rising, then falling, risk of NHL. Rate ratios for intermediate/high-grade lymphoma were increased for the highest levels of lifetime cumulative exposure (RR = 3.7 and RR = 2.3), and were most pronounced for those exposures occurring 10-20 years previously. Hodgkin's disease and multiple myeloma mortality did not appear to be associated with exposure. Associations were stronger for NHL subgroups, suggesting that further analysis by subgroup may be warranted, but the absence of dose-response gradients diminishes the likelihood that associations represent causal relationships.

Cohort Studies↗
PubMed1997

Relationship between pregnancy-induced hypertension and placenta previa: a population-based study.

OBJECTIVE: Our purpose was to investigate, in a large population-based cohort, the hypothesis that the risk of pregnancy-induced hypertension is lower among pregnancies complicated by placenta previa compared with pregnancies occurring in women with fundally implanted placentas. STUDY DESIGN: Data for this retrospective cohort study were derived from the computerized Atlee perinatal database of the Reproductive Care Program, Nova Scotia, Canada. Women who were delivered in the province between 1980 and 1993 were included in the study. Patients with pregnancy-induced hypertension were clinically diagnosed by the presence of elevated blood pressure, proteinuria, or edema. The risk of pregnancy-induced hypertension was compared between women diagnosed with placenta previa and those with a normally implanted placenta, after adjustment for potential confounders through multivariable logistic regression models based on the method of generalized estimating equations. RESULTS: During the 14 years (1980 to 1993), 121,082 singleton pregnancies were registered in the program, 416 (0.4%) of which had a confirmed diagnosis of placenta previa. Women with chronic hypertension had a relative risk of 1.2 (95% confidence interval 0.4 to 3.7) for placenta previa compared with normotensive women. However, the risk of pregnancy-induced hypertension was reduced by half among those with placenta previa (relative risk 0.5, 95% confidence interval 0.3 to 0.7). Adjustments for potential confounders, including maternal age, parity, prepregnancy body weight, prior cesarean delivery, prior spontaneous or induced abortions, and cigarette smoking, had no influence on this association. Analyses on the basis of stratification of women by parity (nulliparous vs multiparous), cigarette smoking (smoker vs nonsmoker), and gestational duration (< 28, 28 to 32, 33 to 36, and > 37 completed weeks) consistently showed reduced risks for pregnancy-induced hypertension among women with placenta previa, indicating that the association was not a result of shortened duration of gestation among women with placenta previa. CONCLUSIONS: The results from this study clearly show a decreased frequency of pregnancy-induced hypertension among those pregnancies with placenta previa. We speculate that the pathophysiologic mechanisms for this finding may be due to altered placental perfusion seen among women diagnosed with placenta previa.

Adult↗
PubMed1997

Demographics, health behaviors, and past drug use as predictors of recall accuracy for previous prescription medication use.

Drug data for pharmacoepidemiologic studies are often ascertained by self-report, but little research has addressed the factors influencing its accuracy. Stratified random sampling was used to select individuals for a study comparing interview data on past prescription drug use with dispensation information from the Group Health Cooperative of Puget Sound pharmacy database. The strata included age, gender, and recency of use. Recall accuracy and its determinants were evaluated for repetitively used non-steroidal anti-inflammatory drugs (NSAIDs), short-term NSAIDs (only a single dispensation), and post-menopausal estrogens. We investigated whether recall accuracy was influenced by education, marital status, race, smoking, alcohol consumption, cumulative drug history, the number of different NSAIDs or estrogens dispensed (both by name and dosage), and the number of dispensations of the drug in question. For repetitively used NSAIDs, recall accuracy was positively associated with the number of NSAID dispensations (the odds of recall were 1.7 [95% confidence interval {CL}: 1.3-2.2] times greater for each additional four dispensations of the NSAID), the total number of drugs dispensed and the number of different NSAIDs dispensed. For estrogen and short-term NSAID use, only higher educational attainment improved recall accuracy: the odds of recall were 4.1 (95% CI: 1.4-11.7) and 2.1 (95% CI: 1.0-4.7) times greater for those with some college compared with those with only a high school degree, respectively. This study demonstrates that predictors of recall accuracy for previous medication use differ by the type of drug and the repetitiveness of its use.

Aged↗
PubMed1997

Econometric approaches to epidemiologic data: relating endogeneity and unobserved heterogeneity to confounding.

The concepts of endogeneity and unobserved heterogeneity are well-known among econometricians. However, these issues are rarely addressed in epidemiologic studies. This paper explores these two concepts, their relationship to each other, and the implications for analysis in epidemiologic studies. An endogenous variable is defined as a predictor variable which is partly determined by factors within the model itself, while unobserved heterogeneity is conceptualized as a vector of missing variables acting through the error term. Under certain assumptions, the simultaneous existence of an endogenous variable and unobserved heterogeneity is shown to act in a manner analogous to confounding. Specifically, this occurs due to an association between the error term in the equation and the endogenous predictor variable. The accepted econometric solution to this problem is to replace the endogenous variable with an 'instrumental variable' which is not correlated with the error term and thus not susceptible to confounding. The validity of these concepts and of the proposed solution are discussed.

Confounding Factors, Epidemiologic↗
PubMed1997

Male and female occupation in relation to miscarriage and preterm delivery in central North Carolina.

PURPOSE: This study was undertaken to evaluate the role of parental occupation in miscarriage and preterm delivery. Previous studies raise the possibility that both male and female exposures could affect pregnancy. METHODS: Data from a population-based study of miscarriage and preterm delivery in central North Carolina were used to examine potential associations with male and female occupation. Medically treated miscarriage cases (n = 418), preterm delivery cases identified through hospital record review (n = 582), and term, normal birth weight controls (n = 787) were sought for telephone interview. The interview included information on jobs the woman held before and during the pregnancy, reports of her partner's job around the time of pregnancy, and information on potential confounding factors. RESULTS: Female employment overall, or in specific jobs, around the time of conception or early pregnancy was not associated with the risk of miscarriage, whereas working during pregnancy, especially in the seventh month, was inversely associated with risk of preterm delivery. Male employment in several industrial occupations was weakly associated with miscarriage (adjusted odds ratios (OR) of 1.6 to 1.8), and somewhat more strongly associated with preterm delivery, particularly for chemists and sheet metal workers (adjusted OR over 3). Restriction to married men strengthened the associations. CONCLUSIONS: Our results are limited by nonresponse, imprecision, incomplete identification of miscarriages, and lack of detailed occupational exposure information. Nonetheless, we found greater support for further examination of male compared to female jobs in relation to pregnancy outcome.

Abortion, Spontaneous↗
PubMed1997

Preeclampsia and preterm birth subtypes in Nova Scotia, 1986 to 1992.

The goal of this study was to evaluate the influence of preeclampsia on preterm delivery, examining whether the association varied among preterm birth subtypes defined by gestational age and precipitating events. A population-based, longitudinal study of the association between mild and severe preeclampsia and preterm birth subtypes was conducted among 59,851 women (resulting in a total of 78,086 pregnancies) delivering singleton live births in the province of Nova Scotia, Canada between 1986 and 1992, utilizing the Nova Scotia Atlee perinatal database. Very preterm (< 33 weeks' gestation) and moderately preterm (33-36 weeks' gestation) births were further classified as occurring due to (1) membrane rupture, (2) medical intervention, and (3) spontaneous onset of labor (before membrane rupture). Mild and severe preeclampsia occurred in 8.7 and 1.7% of pregnancies, respectively, after exclusions of multiple births. After adjustment for confounders by multivariable logistic regression based on the generalized estimating equations, severe preeclampsia was strongly associated with the risk of very preterm birth (RR = 80.8, 95% CI: 54.2-120.6), and moderately preterm birth (RR = 41.8, 95% CI: 34.0-51.4) due to medical intervention. A less dramatically elevated risk of very preterm (RR = 2.1, 95% CI: 1.1-4.0) and moderately preterm (RR = 2.2, 95% CI: 1.7-2.9) birth due to medical intervention was apparent among pregnancies complicated by mild preeclampsia. Very preterm births due to membrane rupture were too rare to examine, but moderately preterm births due to membrane rupture were not associated with preeclampsia. Preeclampsia was associated with an increase in the risk of moderately preterm births due to spontaneous labor (RR = 1.9, 95% CI: 1.3-2.8), but not very preterm births (RR = 1.0, 95% CI: 0.7-1.2). Substantial variability was observed in the association between preeclampsia and preterm birth in relation to the subtypes defined by gestational age and pathway, with strong associations between hypertension and medically induced preterm births. The results indicate a need to separate preterm births into subcategories to properly evaluate the association between preeclampsia and preterm births and interventions to reduce the adverse effects of preeclampsia.

Adult↗
PubMed1997

Influence of gestational age on the time from spontaneous rupture of the chorioamniotic membranes to the onset of labor.

Our goal was to assess the influence of gestational age on the timing of labor onset following spontaneous rupture of the chorioamniotic membranes. The 24,831 patients in the Nova Scotia Atlee perinatal database from 1986 to 1992 whose membranes ruptured prior to labor onset and had live births were analyzed using life-table analysis methods. The probability of labor onset at specified intervals following rupture was markedly lower when rupture occurred earlier in gestation. Pregnancies of < 33 weeks' gestation were less than half as likely as term pregnancies to proceed to labor within 24 hours and pregnancies of 33-36 weeks' gestation were 50-75% as likely as term pregnancies to progress within that period. These data provide clear evidence that the earlier in gestation the rupture occurs, the less likely labor onset is within specified time periods. This pattern supports the contention that preterm rupture of membranes is etiologically distinct from preterm labor.

Amnion↗
PubMed1997

Agreement between self and partner reports of paternal drinking and smoking. The ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood.

BACKGROUND: We examined agreement between self and proxy reports of paternal drinking and smoking behaviour using data collected as part of the prospective, population-based Avon (England) Longitudinal Study of Pregnancy and Childhood. METHODS: Information on the smoking and drinking habits of pregnant women's male partners was obtained through self-administered questionnaires completed by pregnant participants and by their partners. For dichotomous indicators (e.g. smoker versus non-smoker), we evaluated self/proxy agreement by calculating Kappa coefficients and per cent agreement. For ordinal measures of smoking and drinking amounts, we calculated per cent perfect agreement, per cent agreement within one category, and Spearman correlation coefficients. Data from 8414 respondent pairs were included in the analyses. RESULTS: Men's and women's reports of paternal smoking and drinking status were in nearly complete agreement (95% and 98%, respectively). For analyses of smoking and drinking amounts, agreement within one category remained high (90% and 98% for smoking and drinking, respectively), but perfect agreement on amount was somewhat lower (81% and 71%, respectively). Per cent perfect agreement on smoking amount was especially low (50%) when non-smokers were excluded. When couples' reports were not in perfect agreement, women tended to report lower amounts of smoking and drinking for their partners compared to the men's self reports. CONCLUSIONS: Our results suggest that women's proxy reports of their partners' drinking and smoking status can be used with considerable confidence in reproductive epidemiological studies when the enrollment of both women and men as participants is infeasible for financial or logistical reasons. Caution is warranted, however, when proxy reports are used for more detailed information on smoking and drinking amounts.

Adult↗
PubMed1997

Sensitivity of the relation between cumulative magnetic field exposure and brain cancer mortality to choice of monitoring data grouping scheme.

We examined the effectiveness of alternative grouping strategies with respect to cumulative exposure to magnetic fields and brain cancer mortality among electric utility workers. We applied a statistically optimal job-exposure matrix to calculate cumulative exposure over full work histories. We studied the sensitivity of the exposure-disease relation by assigning an array of different quantitative exposure estimates based on six schemes for grouping exposure measurements. The quantitative relation between cumulative magnetic field exposure and brain cancer mortality appeared to be sensitive to the choice of grouping scheme, with the optimized grouping scheme indicating stronger relations than standard schemes.

Analysis of Variance↗
PubMed1997

Influence of hypertensive disorders and cigarette smoking on placental abruption and uterine bleeding during pregnancy.

OBJECTIVE: To assess the influence of hypertensive disorders in pregnancy on the subsequent risk of placental abruption and uterine bleeding of unknown aetiology, and to examine the combined effects of hypertensive disorders and cigarette smoking during pregnancy on the risk of uteroplacental bleeding disorders. DESIGN: Retrospective cohort study. SETTING: Data for this study were derived from the Nova Scotia Atlee Perinatal database, Canada, comprising of women who were delivered in the province between 1980 and 1993. POPULATION: 120,666 pregnancies resulting in singleton births, of which 13,360 pregnancies were complicated by pre-eclampsia and/or chronic hypertension. MAIN OUTCOME MEASURES: Risks and relative risks of placental abruption and uterine bleeding of unknown aetiology in pregnancies complicated by chronic hypertension, mild and severe pre-eclampsia, and chronic hypertension with superimposed pre-eclampsia, each compared with normotensive patients. Adjusted relative risks were obtained through the fit of multivariable logistic regression models based on the method of generalised estimating equations. RESULTS: Chronically hypertensive women had no increased risk of abruption (RR 1.4; 95% CI 0.5-3.6), while women whose pregnancies were complicated by severe pre-eclampsia (RR 3.8; 95% CI 2.1-6.9), and chronic hypertension with superimposed pre-eclampsia (RR 2.8; 95% CI 1.2-6.3) showed strong associations with placental abruption. However, none of the hypertensive disorders were associated with uterine bleeding of unknown aetiology. The association between placental abruption and hypertensive disorders varied by parity. Parous women with chronic hypertension and superimposed pre-eclampsia were at greater risk of placental abruption (aRR 3.8; 95% CI 1.9-7.8) than nulliparous women with chronic hypertension and superimposed pre-eclampsia (aRR 1.6; 95% CI 0.5-4.9). The joint effects of smoking and hypertension had a greater effect on the risk of placental abruption than would have been expected based on their individual effects. CONCLUSIONS: The pattern of association between placental abruption and hypertension varied in relation to the specific type of hypertensive disorder. However, uterine bleeding of unknown aetiology was not associated with hypertension. Findings from this study suggest that placental abruption and uterine bleeding of unknown origin are aetiologically distinct obstetric complications with respect to hypertensive disorders during pregnancy.

Abruptio Placentae↗
PubMed1997

Cancer mortality among electric utility workers exposed to polychlorinated biphenyls.

OBJECTIVES: To assess whether excess mortality from cancer, malignant melanoma of the skin, and cancers of the brain and liver in particular, is associated with long term occupational exposure to polychlorinated biphenyls (PCBs). METHODS: An epidemiological study of mortality was conducted among 138,905 men employed for at least six months between 1950 and 1986 at five electrical power companies in the United States. Exposures were assessed by panels composed of workers, hygienists, and managers at each company, who considered tasks performed by workers in 28 job categories and estimated weekly exposures in hours for each job. Poisson regression was used to examine mortality in relation to exposure to electrical insulating fluids containing PCBs, controlling for demographic and occupational factors. RESULTS: Neither all cause nor total cancer mortality was related to cumulative exposure to PCB insulating fluids. Mortality from malignant melanoma increased with exposure; rate ratios (RRs) relative to unexposed men for melanoma were 1.23 (95% confidence interval (95% CI) 0.56 to 2.52), 1.71 (0.68 to 4.28) and 1.93 (0.52 to 7.14) for men with < 2000, > 2000-10,000, and > 10,000 hours of cumulative exposure to PCB insulating fluids, respectively, without consideration of latency. Lagging exposure by 20 years yielded RRs of 1.29 (0.76 to 2.18), 2.56 (1.09 to 5.97), and 4.81 (1.49 to 15.50) for the same exposure levels. Mortality from brain cancer was modestly increased among men with < 2000 hours (RR 1.61, 95% CI 0.86 to 3.01) and > 2000-10,000 hours exposure (RR 1.79, 95% CI 0.81 to 3.95), but there were no deaths from brain cancer among the most highly exposed men. A lag of five years yielded slightly increased RRs. Mortality from liver cancer was not associated with exposure to PCB insulating fluids. CONCLUSIONS: This study was larger and provided more detailed information on exposure than past investigations of workers exposed to PCBs. The results suggest that PCBs cause cancer, with malignant melanoma being of particular concern in this industry.

Follow-Up Studies↗
PubMed1997

Lung cancer in relation to employment in the electrical utility industry and exposure to magnetic fields.

OBJECTIVES: A recent study found that lung cancer may be associated with exposures encountered in the electrical utility industry. To further evaluate this possibility, data were collected and analysed from five large electrical utility companies in the United States. METHODS: A cohort of 138905 male workers employed between 1950 and 1986 was followed up for mortality to the end of 1988, with 20733 deaths identified of which 1692 were due to lung cancer. Mortality from lung cancer was examined in relation to the duration of employment in specific jobs thought to have high exposure to 60 Hz magnetic fields and to an index of cumulative exposure to magnetic fields based on personal measurements. Exposure to pulsed electromagnetic fields (PEMFs) as estimated from another study was also considered. Poisson regression generated rate ratios for categories of exposure based on comparisons within the cohort adjusted for age, calendar year, race, socioeconomic status, work status, and estimated exposure to asbestos. RESULTS: Mortality rose modestly with duration of work as an electrician or power plant operator reaching rate ratios of 1.4 with > or = 20 years in those jobs but not with duration of work as a lineman or a combination of jobs thought to have high exposures to 60 Hz magnetic fields or PEMFs. Cumulative indices of exposure to 60 Hz magnetic fields and PEMFs were both associated with rate ratios of 1.2-1.3 in the highest intervals. CONCLUSIONS: These data suggest that lung cancer is not strongly associated with duration of employment in specific jobs associated with high potential exposure to 60 Hz magnetic fields or to PEMFs. Small associations of lung cancer with indices of both 60 Hz magnetic fields and PEMFs leave open the possibility that larger associations have been diluted through exposure misclassification. Refined exposure assessment, especially to PEMFs, would be required to evaluate that possibility.

Cohort Studies↗
PubMed1997

Pesticides and childhood cancers.

To evaluate the possible association between pesticides and the risk of childhood cancers, epidemiologic studies published between 1970 and 1996 were critically reviewed. Thirty-one studies investigated whether occupational or residential exposure to pesticides by either parents or children was related to increased risk of childhood cancer. In general, the reported relative risk estimates were modest. Risk estimates appeared to be stronger when pesticide exposure was measured in more detail. Frequent occupational exposure to pesticides or home pesticide use was more strongly associated with both childhood leukemia and brain cancer than either professional exterminations or the use of garden pesticides. Occupational pesticide exposure was also associated with increased risk of Wilms' tumor, Ewing's sarcoma, and germ cell tumors. Residence on a farm, a proxy for pesticide exposure, was associated with increased risk of a number of childhood cancers. Although increased risk of some childhood cancers in association with pesticide exposure is suggested by multiple studies, methodological limitations common to many studies restrict conclusions; these include indirect exposure classification, small sample size, and potential biases in control selection. Opportunities for methodologic improvement in future studies of pesticides and childhood cancers are described.

Brain Neoplasms↗
PubMed1997

Employment, job strain, and preterm delivery among women in North Carolina.

OBJECTIVES: A population-based case-control study was conducted in central North Carolina to assess the relationship between occupational stress and preterm delivery. METHODS: Four hundred twenty-one women delivering infants before 37 weeks' gestation and 612 women delivering infants at term were interviewed a median of 6 months after delivery. Exposure information was collected for all jobs held for at least 1 month during pregnancy. RESULTS: Work in a "high strain" job (i.e., high demand and low control) was not associated with increased risk of preterm delivery compared with work in "low strain" jobs (all other combinations of job demand and control). Narrowing the exposure window to the third trimester did not modify the results. However, women who worked at a high-strain job full-time (odds ratio [OR] = 1.4, 95% confidence interval [CI] = 0.9, 2.0) or for 30 or more weeks (OR = 1.4, CI = 1.0, 2.2) had a modestly increased risk. Several analyses suggested that Black women were at greater risk from job strain than White women. CONCLUSIONS: This study suggests that chronic exposure during pregnancy to work characterized by high demand and low control may be modestly associated with preterm delivery.

Adult↗
PubMed1996

Maternal cigarette smoking as a risk factor for placental abruption, placenta previa, and uterine bleeding in pregnancy.

The authors carried out an epidemiologic study to evaluate the role of maternal cigarette smoking as a potential risk factor for placental abruption, placenta previa, and uterine bleeding of unknown etiology in pregnancy. Data for this prospective cohort study were obtained from women seeking prenatal care at any of the two tertiary, seven regional, or 17 community hospitals in the province of Nova Scotia, Canada, between January 1, 1986, and December 31, 1993. A total of 87,184 pregnancies (among 61,667 women) were registered in the database. Women who smoked during pregnancy (33%) were compared with nonsmokers, and all women were followed until the termination of pregnancy. Placental abruption was indicated in 9.9 per 1,000 pregnancies, while placenta previa and uterine bleeding of unknown etiology were indicated in 3.6 and 58.9 per 1,000 pregnancies, respectively. Women who smoked had a twofold increase in the risk of abruption (relative risk = 2.05, 95% confidence interval (CI) 1.75-2.40) in comparison with nonsmokers, while the relative risk for placenta previa was 1.36 (95% CI 1.04-1.79). However, cigarette smoking was not found to be associated with uterine bleeding of unknown etiology (relative risk = 1.01, 95% CI 0.94-1.08). There was no evidence for an increased risk of uteroplacental bleeding disorders with increasing numbers of cigarettes smoked. All analyses were adjusted for potentially confounding factors through logistic regression models based on the method of generalized estimating equations. The study confirms a positive association between cigarette smoking and placental abruption and a weak association with placenta previa but not with other uterine bleeding. The distinct pattern of results for placental abruption, placenta previa, and uterine bleeding of unknown origin suggests that these three uteroplacental bleeding disorders do not have a common etiology in relation to cigarette smoking.

Abruptio Placentae↗
PubMed1996

Male and female employment in the textile industry in relation to miscarriage and preterm delivery.

To address potential reproductive hazards in textile manufacturing, we conducted a community-based case-control study in central North Carolina. Miscarriage cases were identified from medical records (280 interviewed cases): preterm delivery cases and term, normal birth weight controls (454 and 605, respectively) were identified from area hospitals. Exposures were based on job title, an interview concerning textile-related exposures, expert imputation of exposure based on job titles and interviews, and self-reported exposures by women. Relative to women and men working in nonhazardous occupations, workers in the textile industry were not at increased risk of miscarriage or preterm delivery, with the possible exception of preterm delivery among women and men employed in sectors other than knitting and yarn mills and men employed in yarn mills. Inferred exposures to specific agents were also not associated with adverse pregnancy outcome. Subject to uncertainty in exposure assessment and nonresponse, these data indicate an absence of adverse effects of the textile workplace environment on these pregnancy outcomes.

Case-Control Studies↗
PubMed1996

Placental abruption and its association with hypertension and prolonged rupture of membranes: a methodologic review and meta-analysis.

OBJECTIVE: To conduct a meta-analysis of published studies on placental abruption to examine its incidence, recurrence, and association with hypertensive disorders (chronic hypertension and preeclampsia) and prolonged rupture of membranes (PROM) in pregnancy. DATA SOURCES: We reviewed studies on placental abruption published since 1950, based on a comprehensive literature search using MEDLINE, and by identifying studies cited in the references of published reports. METHODS OF STUDY SELECTION: We identified 54 studies, excluding case reports on placental abruption and studies relating to placenta previa and vaginal bleeding of unknown origin. We also restricted the search to articles published in English. TABULATION, INTEGRATION, AND RESULTS: Studies chosen for the meta-analysis were categorized based on their study design (case-control or cohort), where they were conducted (United States or other countries), source of the data (vital records versus other sources), and magnitude of risk (risk of abruption greater or less than 1.0%). We used both fixed- and random-effects analysis to identify sources of heterogeneity in results among studies. There were striking differences in the incidence of placental abruption between cohort (0.69%) and case-control (0.35%) studies. United States-based studies found a somewhat higher incidence both for cohort (0.81%) and case-control (0.37%) studies compared with studies conducted outside the U.S. (0.60% and 0.26%, respectively). Abruption was more than ten times more common in pregnancies preceded by a pregnancy with abruption. Chronically hypertensive patients were more than three times as likely to develop placental abruption (odds ratio [OR] 3.13, 95% confidence interval [CI] 2.04-4.80) as normotensive patients. The OR for placental abruption was 1.73 (95% CI 1.47-2.04) for patients with preeclampsia. Similarly, women with pregnancies complicated by PROM were more than three times as likely to develop placental abruption (OR 3.05, 95% CI 2.16-4.32). United States-based studies, case-control studies, and studies with an incidence of abruption greater than 1% demonstrated stronger associations between abruption and hypertension and PROM. CONCLUSION: Risk of abruption is strongly associated with chronic hypertension, PROM, and especially abruption in a prior pregnancy, and somewhat more modestly with preeclampsia. The criteria for the diagnosis of placental abruption, hypertensive disorders, and PROM may have introduced variability among the results of these studies. More standardized definitions of these pregnancy complications would improve the comparability of the study results.

Abruptio Placentae↗