Evaluating the threshold of abnormal second trimester multiple marker screens (MMS) associated with intra-uterine growth restriction (IUGR)

Abstract

SCREENS (MMS) ASSOCIATED WITH INTRA-UTERINE GROWTH RESTRICTION (IUGR) ANTHONY ODIBO, CHRISTOPHER RIDDICK, RAEGAN MCDONALD, DAVID STAMILIO, HARISH SEHDEV, GEORGE MACONES, University of Pennsylvania, Obstetrics and Gynecology, Philadelphia, Pennsylvania, New York University, Obstetrics and Gynecology, New York, New York, Pennsylvania Hospital of the University of Pennsylvania Health System, Obstetrics and Gynecology, Philadelphia, Pennsylvania OBJECTIVE: Although unexplained abnormal MMS results have been associated with adverse perinatal outcomes including IUGR, the reported critical thresholds for the analytes have been conflicting. Our objective is to evaluate the optimal thresholds for abnormal MMS that are associated with IUGR. STUDY DESIGN: A nested-case control study from our perinatal database. MMS analyte levels (Multiples of Median, MoM) of cases with IUGR (birthweight !10th percentile for gestational age) were compared with a control group without IUGR. Pregnancies with fetal anomalies or aneuploidy were excluded. Biochemical markers evaluated include alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol (uE3). Using ROC curves, the optimal thresholds of MMS (OTM) associated with IUGR were determined. RESULTS: Of 2045 patients with complete MMS records identified from the databse, there were 229 (11%) with IUGR. The OTM associated with IUGR were: AFP >2.0 MoM, with OR of 2.5, 95% CI 1.2-5.2; hCG >2.5 MoM, OR 2.7, 95% CI 1.1-6.9, and uE3 !0.9 MoM, OR 2.2, 95% CI 1.5-3.3. At AFP levels >3.0 MoM, the OR (95% CI) was 6.5 (1.8-23.1) for the association with IUGR. The sensitivity, specificity, positive and negative predictive values for predicting IUGR in the presence of at least one abnormal MMS were: 46%, 66%, 11% and 90% for predicting IUGR, respectively; and with two abnormal analytes 15%,96%, 31% and 90%, respectively. Elevated AFP >2.0 MoM and hCG >2.5 MoM were the most specific markers for IUGR, with specificity of 94% and 95% respectively. When all 3 analytes were abnormal, the specificity for predicting IUGR increased to 99%. CONCLUSION: Abnormal MMS results are associated with IUGR. As a screening tool for IUGR, the biochemical markers were associated with poor sensitivity. Elevated AFP and hCG were however, highly specific in predicting IUGR. The provided thresholds could be useful in designing policies regarding women with abnormal MMS who would benefit most from sonographic screening for IUGR. 423 THE RISE OF PREECLAMPSIA RATES: THE CONTRIBUTION OF INCREASING MATERNAL OBESITY YVETTE LACOURSIERE, LOIS BLOEBAUM, JEFFREY DUNCAN, MICHAEL VARNER, University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah, Utah Department of Health, Salt Lake City, Utah, University of Utah, Maternal-Fetal Medicine, Salt Lake City, Utah OBJECTIVE: Preeclampsia is associated with increasing BMI. Maternal overweight and obesity has increased 40% over the past decade in Utah. Reports documenting the impact of rising BMI on preeclampsia rates have not been published. Thus we set out to explore if the increase in maternal obesity has affected preeclampsia rates in the state of Utah, after accounting for changes in maternal age and race distribution. STUDY DESIGN: Using computerized birth certificates, data on all women who delivered live-born singleton infants in Utah from 1991 to 2001 were collected. Pre-pregnancy BMI (kg/m) was stratified by categories: 20-24.9 normal, >25 overweight/obese. Temporal trends of pre-pregnancy BMI and preeclampsia were analyzed. Changes in maternal age and race distributions were characterized. The adjusted RR was calculated and attributable fractions for all years in the interval were determined. RESULTS: 180,311 nulliparous women were included in the analysis. From 1991 to 2001, preeclampsia among nulliparous women increased from 5.2 to 8.2%. There has been a decrease in women aged !19 and no significant increase in nulliparas >35 years during the interval. There was a 2-fold increase in Hispanic women, but the rates of preeclampsia are not higher in this subgroup compared to non-Hispanics. After excluding multiple gestations and controlling for maternal age, race/ethnicity, education, weight gain, gestational age, chronic hypertension, and diabetes, the converted adjusted RR were stable over the interval. The attributable fraction of preeclampsia in women with a BMI >25 before pregnancy ranged from 0.53 to 0.63. In 2001, nearly 1 in 5 of all nulliparous preeclampsia were attributable to overweight and obesity. CONCLUSION: Increasing rates of maternal overweight and obesity have resulted in an increase in preeclampsia from 1991 to 2001. This is the first study to document this phenomenon, while accounting for other changes in maternal demographics and risk factors.