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Biomedical subjects

M E Tompkins

Publications and source records attributed to M E Tompkins.

12 recordsLinked to original sources
PubMed2000

Racial differences in temporal changes in newborn viability and survival by gestational age.

This study examines trends in the rates of very preterm, moderately preterm and gestational age-specific neonatal mortality, and in the gestational age limit of viability in South Carolina (SC) from 1975 to 1994. We also investigate whether trends were similar between African-Americans and Whites. We hypothesised that disproportionate reductions in gestational age-specific mortality, rather than any major changes in the gestational age distributions of either race group, underlie any increasing racial disparity in overall mortality rates. During 1975-94, single livebirths, who were born to mothers resident in SC and were either White or African-American based on recorded maternal race, were selected for the investigation. We define the gestational age limit of viability as the gestational age at which > or = 50% of infants in the population died within 28 days of life. Although preterm percentages have not improved, there was a marked decline in neonatal mortality. Gestational age-specific neonatal mortality decreased for both race groups, although there were greater reductions for White preterm infants. By the end of the study period, the African-American neonatal mortality rate was 2.3 times that of Whites and the gestational age at which 50% of newborns died within 28 days of life was 24.5 weeks for Whites and 23.9 weeks for African-Americans. The ongoing decline in neonatal mortality continues to be mainly due to reductions in gestational age-specific neonatal mortality, probably related to high-risk obstetric and neonatal care. Technological developments in these areas may have differentially benefited Whites, resulting in an increasing racial disparity in neonatal mortality rates. Preterm African-American infants no longer have a marked survival advantage over White infants, even at the gestational age limit of viability.

Black or African American↗
PubMed1999

Trends and racial differences in birth weight and related survival.

OBJECTIVE: In the past two decades, infant mortality rates in the United States declined in African-American and White populations. Despite this, racial disparities in infant mortality rates have increased and rates of low birth weight deliveries have shown little change. In this study, we examine temporal changes in birth weight distributions, birth weight specific neonatal mortality, and the birth weight threshold for an adverse risk of survival within both racial groups in order to explore the mechanisms for the disparities in infant mortality rates. METHOD: Single live births born to South Carolina resident mothers between 1975 and 1994 and considered White or African-American based on the mother's report of maternal race on the birth certificate were selected for investigation. We define the birth weight threshold for adverse survival odds as the birth weight at which 50% or more of infants in the population died within the first month of life. RESULTS: Despite significant increases in very low birth weight percentages, neonatal mortality rates markedly declined. Birth weight specific neonatal mortality decreased for both races, although greater reductions accrued to White low birth weight infants. By the end of the study period, the birth weight at which over 50% of newborns died within the first month of life was 696 g for Whites and 673 g for African-Americans. DISCUSSION: The ongoing decline in neonatal mortality is mainly due to reductions in birth weight specific neonatal mortality, probably related to high-risk obstetric and neonatal care. Technological developments in these areas may have differentially benefited Whites, resulting in an increasing racial disparity in mortality rates. Moreover, the relatively greater and increasing mortality risk from postmaturity and macrosomia in infants of African-America mothers may further exacerbate the racial gap in infant mortality.

Female↗
PubMed1992

Validity of postnatal assessments of gestational age: a comparison of the method of Ballard et al. and early ultrasonography.

This study investigates the accuracy of the postnatal gestational age assessment method of Ballard et al. to predict very preterm, preterm, term, postterm, and small-for-gestational-age infants, with gestational age by early ultrasonography used as the gold standard. Sensitivity, specificity, and predictive value were examined for each gestational age category, with 4193 single live births occurring during the period from 1982 through 1989 with an ultrasonographic examination done by 20 weeks' gestation and a postnatal assessment at 28 to 44 weeks. These data indicate that the postnatal assessment overestimated the gestational age of preterm births, resulting in an underestimation of very preterm and preterm percentages. Nearly three fourths of the postterm births by ultrasonography were misclassified by the method of Ballard et al. because of underestimation of postterm gestational ages. These data indicate that, for research purposes, appreciable misclassification of preterm, postterm, and small-for-gestational-age infants will occur if gestational age is determined by the technique of Ballard et al.

Evaluation Studies as Topic↗
PubMed1992

Ethnic variation in postnatal assessments of gestational age: a reappraisal.

While the possibility of an ethnic bias in postnatal assessments of gestational age has been suggested by several investigators, others have reported that postnatal assessments do not provide biased estimates in non-White ethnic groups. In the light of this ongoing controversy, this study examines the validity of the Ballard postnatal assessment of gestational age by ethnicity, using a relatively large hospital data base that allows for the inspection of ethnic variations in the agreement between the Ballard assessment and last menstrual period (LMP). The results indicate that there is a greater over-estimation of the LMP interval by the Ballard method in Blacks compared with Whites and suggest that systematic differences exist by ethnicity of mother in the agreement between the Ballard postnatal assessment and the LMP interval. After taking maternal characteristics and pregnancy complications into account, for a given gestational age interval, Blacks have on average a greater level of maturity as measured by Ballard. One interpretation of these findings is that postnatal assessments may provide biased over-estimates of the LMP gestational age interval in certain ethnic groups. An alternative interpretation of these data is that the gestational age interval based on LMP is not a valid indicator of fetal maturity, readiness for birth and infant risk status across all ethnic groups.

Bias↗
PubMed1991

Source of bias in prenatal care utilization indices: implications for evaluating the Medicaid expansion.

BACKGROUND: Recent expansions in eligibility for coverage of prenatal care services by the Medicaid program reflect national initiatives to improve pregnancy outcomes. This study investigates the potential impact that completeness of reporting of prenatal care and gestational age variables and strategies to impute missing data may have on evaluations of the Medicaid expansion. METHODS: This study, examining 15 years of vital record data from a single state and comparing 1 year of data from four mid-Atlantic states, selected single live births to resident mothers for analyses. The "day 15" and the "preceding case" methods were used to impute missing gestational age data. RESULTS: Considerable temporal and geographic variation was detected in completeness of reporting of variables used to construct prenatal care indices. After imputing values for cases with missing data, the proportion of cases for which adequacy of prenatal care utilization could not be determined ranged from 3% to 24% among the states investigated. For those cases where gestational age data could be imputed, the distribution of prenatal care utilization was not markedly disparate from those cases with complete reporting of gestational age. CONCLUSIONS: The results indicate that variations in reporting, decisions regarding the treatment of missing data, and the choice of the denominator can alter prenatal care utilization percentages and have implications for evaluations of the impact of the recent Medicaid expansion on prenatal care utilization.

Bias↗
PubMed1989

A comparison of gestational age reporting methods based on physician estimate and date of last normal menses from fetal death reports.

Utilizing 10,587 cases from the 1980 National Center for Health Statistics Fetal Death Statistics File, we examined the comparability of two methods of determining the gestational age of a fetal death, the calculated interval from date of last normal menses (DLNM) and the physician's estimate. The physician estimated gestational age distribution exhibits even number digit preference and a distinct clustering at the 40-week value. The DLNM distribution appears more smoothly distributed but with a more pronounced post-term tail. An exact agreement between the two methods is observed in only 27.9 per cent of the cases. A 1.7 week mean difference between the methods indicates a systematic underestimation by physician reported gestational age when compared to that calculated from the DLNM, potentially biasing gestational age distributions when the physician estimate is substituted for cases with a missing DLNM. Over 8 per cent of cases 20+ weeks by DLNM are estimated as less than 20 weeks by the physician. This underestimation has important implications for the completeness of reporting of fetal deaths on vital records and the comparability of fetal death rates. Further, it may limit investigations of the completeness of reporting of less than 500 gram live births.

Female↗
PubMed1989

Variations in the reporting of gestational age at induced termination of pregnancy.

Utilizing the 1980 Induced Abortion File maintained by the National Center for Health Statistics, we compared gestational age from date of last normal menses and the physician-based estimate of gestational age. An average .51 week difference between the two methods was observed. Beyond seven weeks gestation, the date of last normal menses value was underestimated by the physician-based estimate with a markedly greater divergence after 20 weeks. A relatively greater underestimation of the date of last normal menses interval by the physician estimate was apparent for Whites after 13 weeks. The data of last normal menses value for non-state residents was overestimated across the entire range of the date of last normal menses gestational age distribution until 21 weeks.

Abortion, Induced↗
PubMed1985

The risk of low birth weight. Alternative models of neonatal mortality.

The authors examine the use of the infant's weight at birth to estimate its risk of mortality by the 28th day of life. The performance of several commonly employed statistical models is compared for the population of single births to resident South Carolina mothers in 1975-1980. A log-linear function, fitting the natural logarithm of the probability of neonatal mortality to birth weight, performs far better in this analysis than a quadratic or a logistic model or a model using the logarithm of the probability of survival. The parsimonious log-linear model also appears preferable to more complex models with additional parameters. The authors use the model in an analysis of data in two-year periods to demonstrate its value as an indicator of underlying changes in neonatal prospects and its easily interpreted parameters. The results highlight the importance of changes in neonatal mortality affecting low birth weight infants, which produce a noticeable shift in the range in which low birth weight is associated with the risk of mortality. These have proven more important in accounting for the decline in mortality rates than have changes affecting only neonates with more typical birth weights in South Carolina in 1975-1980.

Birth Certificates↗
PubMedDate not supplied

Gestational age reporting and preterm delivery.

This study examines recent trends in the reporting completeness and quality of gestational age estimates derived from the date of the last normal menses (DLNM) as reported in South Carolina vital records from 1974 to 1985. Noteworthy improvements in the completeness of reporting emerged during this period with a decline from 31.1 percent missing information in 1974 to 6.6 percent missing in 1985. Completeness of reporting and strategies for imputing values for missing data were analyzed for their impact on the calculation of the percentage of preterm live births. The results indicate that the underreporting of gestational age can lead to marked underestimation of the preterm percentage in a population and to misinterpretation of trends in these percentages. Based on the results of this analysis, it is recommended that preterm percentages be based on cases with DLNM gestational age values between 20 and 50 weeks. Since cases with missing or implausible gestational age data have a greater risk of a poor pregnancy outcome, these findings emphasize the importance of identifying both the completeness of data reporting and the use of imputation and deletion strategies when employing population-based DLNM data to calculate gestational age related indicators.

Adolescent↗
PubMedDate not supplied

Racial differences in the relation of birth weight and gestational age to neonatal mortality.

Utilizing South Carolina live birth-infant death cohort files for the period 1975-80, this study examines the bivariate distribution of birth weight-gestational age (BW-GA), intrauterine growth curves, and BW-GA specific neonatal mortality rates (NMRs) by race. Comparison of BW-GA distributions revealed an appreciable shift between racial subgroups. Nonwhites, on the average, were born 1 week earlier and 270 grams lighter in weight than whites. In addition to racial differences in rates of intrauterine growth, nonwhites experienced lower BW-GA NMRs than whites in BW-GA categories less than 3,000 grams and less than 38 weeks. However, the improved mortality experience of nonwhites at more immature BW-GA categories was not consistently present when different cause-specific NMRs were considered. These persistent racial variations highlight continuing issues regarding both the use of a single norm for defining low birth weight or prematurity and the role of nonsocioeconomic factors related to racial BW-GA distribution and mortality disparities. As birth weight and gestational age represent empirical indicators of the maturity and survivability of an infant at birth, these data and previous supporting research raise further concerns regarding the ability of these indicators to accurately reflect equivalent fetal development and subsequent risk of mortality among racial groups.

Birth Weight↗
PubMedDate not supplied

Discordance between LMP-based and clinically estimated gestational age: implications for research, programs, and policy.

This study examines the comparability between the last menstrual period-based and clinically estimated gestational age as collected on certificates of live birth. It explores whether sociodemographic or delivery characteristics influence their agreement and contrasts health status and health care utilization indicators, such as preterm, small for gestational age, and adequacy of prenatal care percentages, produced by each gestational age measure. The 1989-91 South Carolina public use live birth files were used for this analysis. A total of 169,082 single births to resident mothers were selected for investigation. The clinically estimated gestational age distribution exhibited a higher mean and a tendency toward even number digit preference. The last menstrual period-based measure produced higher preterm and postterm percentages. More than 60 percent of the last menstrual period-based preterm births were classified as preterm by the clinical estimate. The sensitivity of the clinical estimate was 27 percent for postterm births. The overall concordance (the percentage of cases with the same value for both measures) was 47 percent, but it varied considerably by gestational age. Between 30 and 35 weeks, the clinical estimate exceeded the last menstrual period-based value by 2 weeks or more for more than 40 percent of the cases. Concordance also varied by race of mother, hospital delivery size, trimester prenatal care began, and birth weight. The last menstrual period-based and the clinically estimated gestational age distributions exhibited notable dissimilarities, produced marked differences in health status indicators, and varied in concordance by gestational age and by sociodemographic, prenatal care, and hospital characteristics. These systematic differences suggest that a transition from the traditionally used last menstrual period-based measure to the clinical estimate or a composite measure will not produce uniform results across geo-political areas and at-risk groups but will be appreciably influenced by population and health care characteristics.

Birth Certificates↗