Predicting intrauterine growth retardation in sibships while considering maternal and infant covariates

A new method for measuring misclassification of maternal sets in maternally linked birth records: true and false linkage proportions

OBJECTIVES

Numerous studies have used maternally linked birth records to investigate perinatal outcomes, maternal behaviors, and the quality of vital records birth data. Little attention has been given to assessing errors in the linkages and to understanding how such errors affect estimates derived from the linked data. The author developed a framework for conceptualizing maternal linkage error and measures for quantifying it, and examined the behavior of the new measures in a maternally linked file.

METHODS

Linkage errors were conceptualized as misclassification, with the classes being the maternal sets (records classified as representing different births to the same woman). The true linkage proportion, analogous to sensitivity, was used to capture the degree to which all of a woman's births were assigned to a single maternal set; the false linkage proportion, analogous to specificity, was used to capture the degree to which the assigned maternal sets combined births from different women. The behavior of the two proportions was examined by introducing increasing degrees of linkage error into a maternally linked file.

RESULTS

Both measures indicated greater misclassification with increasing simulated linkage errors.

CONCLUSIONS

The new measures may be a useful tool for assessing the quality of maternally linked data, as well as other types of linked records where the linkages are within a single file. This is a necessary step towards developing methods for addressing misclassification bias in studies of maternally linked records through sensitivity analysis, adjustment, and other means.

Decrease in severity of intrauterine growth retardation in subsequent pregnancies

OBJECTIVE

Intrauterine growth retardation (IUGR) is likely to recur in a subsequent pregnancy. We investigated the obstetric features of recurrent cases and the severity of IUGR by comparing initial and subsequent deliveries.

METHODS

From a total of 12,567 deliveries, 95 women who were delivered of small-for-gestational-age (SGA) infants and who became pregnant again within 5 years, were enrolled. A retrospective, comparative study of recurrent and non-recurrent groups was performed.

RESULTS

Twenty-two of ninety-five women gave birth to SGA infants again, and a relatively high risk of recurrence was confirmed, but no single recurrence-associated features were revealed. Within the recurrent group, the degree of IUGR was more severe in only five cases in the subsequent pregnancy.

CONCLUSIONS

IUGR tends to recur, but does not increase in severity in most cases. We conclude that there is no need for excessive concern about the recurrence of IUGR.

Perinatal morbidity associated with violence experienced by pregnant women

OBJECTIVE

We investigated whether physical assault is independently associated with an adverse obstetric outcome.

STUDY DESIGN

We compared the perinatal outcomes of 32 indigent women who reported being physically abused during pregnancy with those of 352 control subjects who denied ever being assaulted. Patients were classified into the appropriate category on the basis of a structured interview. Logistic regression analyses were performed to estimate the relative risk of adverse outcome while adjusting for confounders.

RESULTS

Women assaulted in the current pregnancy were twice as likely to have preterm labor as compared with those who denied assault. In addition, crude odds ratios showed a twofold increased risk of chorioamnionitis in assault victims. No difference between abused and nonabused women was noted in the prevalence of preterm delivery, pregnancy-induced hypertension, cesarean section, meconium staining, infant birth weight, Apgar scores, intrauterine growth retardation, fetal distress, fetal death, neonatal seizures, sepsis, or admission to the intensive care unit.

CONCLUSIONS

This study demonstrates that physical assault during pregnancy is associated with preterm labor and chorioamnionitis. Screening for ongoing assault should be incorporated into routine prenatal care to identify women at risk of complications.

Scope and strategies of genetic epidemiology: analysis of articles published in Genetic Epidemiology, 1984-1991

Genetic epidemiology is a relatively new discipline that seeks to unravel the role of genetic factors and their interactions with environmental factors in the etiology of diseases, using population and family study approaches. To characterize the overall direction and emphasis of research strategies used in this field, we reviewed original research articles published in the journal Genetic Epidemiology since its inception in 1984 until the end of 1991. Of 259 published original articles, 92 (35%) focused primarily on methodologic/statistical developments, most commonly in the area of linkage analysis/gene mapping, and 167 (65%) articles were applied or data-derived. Only 42 articles (16%) were population studies, and 217 (84%) were family studies. Most family studies dealt with genetic analysis of pedigree data using segregation and linkage analyses. Of the 137 applied family studies, 73 (53%) were drawn from well-defined populations, and only 40 (29%) considered specific environmental factors in their analyses. These findings clearly indicate a rapid growth in the methodologic and statistical aspects of genetic epidemiology, and in the emphasis on family-based studies and genetic analysis methods. Further developments in genetic epidemiology will require greater integration of epidemiologic approaches of study design and analyses into population and family studies of disease etiology.