Faculty Bibliography

OBJECTIVE:The purpose of this study was to examine if neonatal mortality rates (NMR) based on birth weight discordance (BWD) differ based on mode of delivery. STUDY DESIGN/METHODS:The population-based US "matched multiple birth" database (1995 to 1998) was used to examine the effect of vaginal/vaginal (VV) and cesarean/cesarean (CC) modes of delivery (MOD) on neonatal mortality (<28 days after birth). Births at <32 weeks, congenital malformations, chromosomal anomalies, and discordant MOD (vaginal/cesarean) were excluded. The association between MOD (with CC as the reference) and neonatal mortality was expressed as relative risks (RR) with 95% CI, derived from logistic regression models. RESULTS:The NMR increased with increasing degrees of BWD regardless of mode of delivery. CC was associated with decreased NMR when BWD was between 20% and 40%, but this reached significance at BWD > or =40%; VV pairs had a 1.6-fold (95% CI 1.1-2.2) increased NMR compared with CC. CONCLUSION/CONCLUSIONS:In twins with BWD <40%, MOD has no effect on NMR. Beyond or equal to 40% discordance, there was lower NMR with cesarean-cesarean delivery.

OBJECTIVE:The purpose of this study was to evaluate temporal trends in abruption risk and to assess how much underlying changes in the clinical determinants may have affected these trends. STUDY DESIGN/METHODS:We used the National Hospital Discharge Summary data (1979-2001), an annual survey of sampled non-federal, short stay, general, and specialty hospitals in the United States. Trends in abruption were assessed for the periods 1979 through 1981 and 1999 through 2001. Clinical determinants of abruption that were evaluated included hypertensive diseases, anemia, gestational diabetes mellitus, preterm labor, preterm premature rupture of membranes, chorioamnionitis, oligohydramnios, obstetric shock/trauma, uterine tumors, short umbilical cord, and velamentous cord insertion. Temporal trends in abruption were examined before and after adjustment for determinants through multivariable logistic regression. RESULTS:The rate of abruption increased 92% (95% CI, 88, 96) among black women between 1979-1981 (0.76%; n = 13,584 women) and 1999-2001 (1.43%; n = 18,960 women). Among white women, the rate increased by 15% (95% CI, 14,16) over the same period, from 0.82% (n = 66,186 women) in 1979-1981 to 0.94% (n = 59,284 women) in 1999-2001. The determinants that were associated with trends in abruption included anemia, gestational diabetes mellitus, preterm labor, short umbilical cord, and velamentous cord insertion, although their effects varied substantially by maternal race. CONCLUSION/CONCLUSIONS:The temporal increase in rates of abruption may reflect a true increase in risk or may be the result of improved diagnosis of both abruption and its determinants. Although the cause of abruption is still speculative, the trend is of concern and deserves scrutiny.

OBJECTIVE:The purpose of this study was to determine the best available antepartum fetal testing methods according to the underlying pathophysiologic condition. STUDY DESIGN/METHODS:We reviewed the current literature and our clinical experience with respect to condition-specific antepartum fetal testing. RESULTS:The efficacy of most antepartum tests that we use today is not supported by randomized controlled clinical trials, but from observational nonrandomized studies and expert opinion (evidence levels II or III). CONCLUSION/CONCLUSIONS:Based on the available evidence, the accuracy of a test depends on the underlying pathophysiologic condition. To improve accuracy, we must use condition-specific fetal testing.

OBJECTIVE:To determine whether differences in the clinical entities of HELLP syndrome and severe preeclampsia are associated with different placental lesions. STUDY DESIGN/METHODS:This was a case control study of singleton pregnancies with HELLP syndrome or severe preeclampsia. Archived pathology slides were retrieved and reviewed. Clinical and histopathological features were compared between the two groups. RESULTS:There were 31 women with HELLP syndrome and 56 with severe preeclampsia. HELLP syndrome was associated with epigastric pain and higher levels of LDH, bilirubin, liver enzymes and fibrin degradation products. Hemoglobin, hematocrit and platelet counts were lower. Abruption lesions of the placenta were less common with HELLP syndrome (Odds Ratio 0.1 95% Confidence Interval 0.01,0.8). None of the other 22 placental features examined were different between the two conditions. CONCLUSION/CONCLUSIONS:The significant overlap between HELLP syndrome and severe preeclampsia for both clinical and placental features suggests that the two conditions represent a spectrum of essentially the same pathophysiologic process.

OBJECTIVE:The purpose of this article was to propose guidelines for the design, execution, interpretation, and reporting of economic evaluation studies in obstetrics. Study design We performed a PubMed search of economic evaluation articles to identify those articles that deal with the quality of published economic evaluation studies, the development of guidelines, and the development of checklists/guidelines for the reporting of economic evaluation studies. All other articles were excluded from the review. RESULTS:We identified 160 articles. We included 8 articles in our review that reported on the quality of published economic analyses, 12 articles that reported on guidelines, and 3 articles that reported on checklists/guidelines that are used by journals. There were 2 articles that dealt with the quality of published economic evaluations in obstetrics and gynecology, both of which showed less than optimal quality. There were only 4 articles that provided some general guidelines for the reporting of economic evaluations in obstetrics and gynecology. We found no articles on any checklist/guidelines for the reporting of economic evaluation studies in obstetrics and gynecology. CONCLUSION/CONCLUSIONS:There is a need to improve the design, execution, interpretation, and reporting of economic evaluation studies in obstetrics.

OBJECTIVE: The purpose of this study was to validate prospectively a previous retrospectively established nomogram for the prediction of gestational age using transcerebellar diameter, especially in the third trimester. STUDY DESIGN: In a previous study, we retrospectively constructed a cross-sectional nomogram using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses. In the present study, this nomogram was validated prospectively on the basis of patients who were seen between August 2002 and May 2003 and who were carrying non-anomalous and non-malformed singleton gestations between 14 and 42 weeks (n = 2597 gestations). The actual gestational age was then subtracted from the predicted gestational age, and the concordance between actual and predicted gestational ages was assessed based on the Pearson correlation (r). RESULTS: Concordance between the actual and predicted gestational age was high (r = 0.92; P < .0001). This agreement was superior in the second trimester (r = 0.93; P < .0001) than in the third trimester (r = 0.81; P < .001). Between 17 and 21 weeks, and between 22 and 28 weeks of gestation, the predicted gestational age ranged between 0 and 4 days, and between 0 and 2 days, respectively, of actual gestational age. Between 29 and 36 weeks of gestation, predicted gestational age was within 5 days of actual gestational age; at 37 weeks of gestation, the predicted gestational age was discrepant by 9 days. CONCLUSION: This prospective study demonstrates that transcerebellar diameter measurement is an accurate predictor of gestational age, even in the third trimester of pregnancy.

OBJECTIVE:To estimate the pattern of maternal vascular reactivity in normal and high-risk pregnancies using postocclusion brachial artery diameter. METHODS:Prospective, longitudinal study of 44 low-risk singleton pregnancies and 28 high-risk pregnancies, defined as pregestational diabetes (n = 7), chronic hypertension (n = 4), twin gestation (n = 6), and a previous history of preeclampsia, fetal growth restriction, or vascular disease (n = 11). During each trimester, the brachial artery was ultrasonographically imaged above the antecubital crease. Brachial artery diameter was measured and then occluded for 5 minutes using an inflated blood pressure cuff. Changes in brachial artery diameter at 1 minute after occlusion were expressed as percent change from baseline and were compared across trimesters for both low-risk and high-risk groups, adjusting for potential confounders. RESULTS:Brachial artery diameters were increased after occlusion in every trimester for all groups. For low-risk women, the degree of postocclusion brachial artery dilatation was similar in the first and second trimesters, but was lower in the third trimester. In the first trimester, low-risk women had significantly greater brachial artery diameter increases at 1 minute compared with high-risk singleton pregnancies (19% compared with 12%; P <.001). Compared with low-risk women, pregnancies complicated by pregestational diabetes or chronic hypertension had significantly smaller 1-minute brachial artery diameter changes in the first trimester (7.0 +/- 0.5%, P <.001), whereas twin gestations had greater brachial artery responses (22.9 +/- 6.0%, P <.001). Women with previous preeclampsia or vascular disease had responses similar to low-risk women. CONCLUSION/CONCLUSIONS:Maternal vascular reactivity as assessed by postocclusion brachial artery dilatation decreases in the third trimester in both low-risk and high-risk women. In addition, singleton pregnancies at high risk for preeclampsia display decreased brachial artery reactivity compared with low-risk women.

OBJECTIVE:Time is an important variable in understanding the recent increase in twin deliveries in the United States. Therefore, this study was designed to estimate the influences of maternal age, period (year) of delivery, and maternal-birth-year cohort on trends in rates of twin deliveries. METHODS:United States natality data were used to assess trends in twin pregnancies resulting in live births. This age-period-cohort analysis included 7, 5-year maternal-age groups (15-19 through 45-49 years), 6 twin delivery periods (1975, 1980, 1985, 1990, 1995, and 2000), and 12, 5-year maternal birth cohorts (1926-1930 through 1981-1985). The independent effects of maternal age, twin delivery period, and maternal birth cohort on twin delivery rates for blacks and whites were modeled using Poisson regression techniques. RESULTS:Our study assessed 95,042 blacks and 401,989 whites with twin deliveries. Twin deliveries increased by 46% for blacks and 62% for whites from 1975 to 2000, with the largest increase occurring in the year 2000. For blacks, maternal age had the strongest impact on the increasing twin delivery rates, followed by period of delivery. For whites, the greatest effect was due to period of delivery, followed by maternal birth year cohort and, lastly, maternal age. CONCLUSION/CONCLUSIONS:Our data confirm the importance of nature's biologic contribution of maternal aging to twin delivery rates, but suggest that recent changes in the environment surrounding pregnancy (nurture) also influence twin delivery rates. The relative contributions of biologic versus environmental influences appear to differ among blacks and whites.