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254 CHANGES IN FETAL PRESENTATION IN TWIN PREGNANCIES STE-PHEN T. CHASEN1, STACEY SPIRO1, FRANK CHERVENAK1, 1Weill MedicalCollege of Cornell University, Obstetrics and Gynecology, New York, NY

OBJECTIVE: Our objective was to describe the rate of spontaneous versionin twins in the third trimester, as well as the correlation between antepartum andbirth presentation.

STUDY DESIGN: Twin pregnancies at $20 weeks evaluated in ourultrasound unit from 1998-2001 were identified. Gestational age was dividedin 4 intervals: 20-23; 24-27; 28-31; and 32-36 weeks. Pregnancies evaluated in < 3intervals or delivering at < 34 weeks were excluded. Fetal presentation wascategorized as cephalic (C) or non-cephalic (NC). Records were reviewed fordemographic information and birth presentation. Chi-square was used tocompare distributions of presentations, and Cramer’s V measure of associationwas used to correlate presentations in individual pregnancies betweenantepartum intervals and birth.

RESULTS: 207 pregnancies were included. Antepartum and birth pre-sentations are seen below (Table). The distribution of fetal presentationschanged significantly over time (P < 0.001), though they were similar betweeninterval 4 and birth (P = 0.75). Correlation between antepartum and birthpresentation in individual pregnancies increased throughout the 4 intervals,with V = 0.16 (P = 0.06) and V = 0.57 (P < 0.001) between birth and intervals 1and 4, respectively. While all C/C pregnancies at $28 weeks delivered witha cephalic first twin, only 73% of pregnancies with an NC presenting twin at$28weeks delivered with an NC presenting twin. No correlation was seen betweenparity, gender, birthweight, ormode of conception and fetal presentation or rateof spontaneous version.

CONCLUSION: Many twins undergo spontaneous version in the thirdtrimester, though there is excellent correlation between presentation at 32-36

December 2003Am J Obstet Gynecol

S132 SMFM Abstracts

EFFECT OF EARLY MATERNAL WEIGHT GAIN IN MOTHERS OFTRIPLETS WITH A NORMAL PRE-PREGNANCY BODY MASS INDEXGEETA SHARMA1, ROBIN B. KALISH1, DEBBIE J. RHEA2, LOUIS G.KEITH3, ISAAC BLICKSTEIN4, 1Weill Medical College of Cornell University,Obstetrics and Gynecology, New York, NY 2Matria Healthcare�, Inc, ClinicalResearch, Marietta, GA 3Northwestern University, Obstetrics and Gynecology,Chicago, IL 4Kaplan Medical Center and the Hadassah-Hebrew UniversitySchool of Medicine, Obstetrics and Gynecology, Jerusalem, Israel

OBJECTIVE: We investigated the influence of maternal weight gain onneonatal outcomes in triplet pregnancies.

STUDY DESIGN: We performed a retrospective analysis of live-born tripletpregnancies with a normal pregravid body mass index in a group comprising1195 (65.5%) nulliparas and 625 (34.5%) multiparas. Total triplet birth weight,gestational age at delivery, and frequency of very low birth weight neonates(VLBW) were compared in patients who gained weight below or above averageper week.

RESULTS: Compared with nulliparas, multiparas had significantly highertotal triplet birth weight (5728 ± 1280 vs 5303 ± 1300 g, P < 0.001) and fewerVLBW infants (19.3% vs 27.8%, OR 0.62, 95% CI 0.5,0.7). Mothers who gainedmore than average weight had a significantly higher total triplet birth weight(multiparas: 5846 ± 1246 vs 5604 ± 1305 g, P = 0.02; nulliparas: 5487 ± 1307 vs5118 ± 1268 g, P < 0.001) and fewer VLBW infants (multiparas: 17.1% vs 21.3%OR 0.76, 95% CI 0.6,0.96; nulliparas: 23.9% vs 31.8% OR 0.67, 95% CI 0.6,0.8).Total triplet birth weight significantly correlated with weight gain for both paritygroups (R2 0.95 and 0.9, respectively).

CONCLUSION:Above average weight gain in triplet pregnancies is causallyrelated with improved neonatal outcomes in both nulliparas and multiparas.

IS THROMBOPHILIA WORKUP JUSTIFIED AFTER TWO UNEXPLAINEDFETAL LOSSES? ZOHAR NACHUM1, AMIR WEISS1, YASER HUJEIRAT2,STAVIT SHALEV-ALON2, RAED SALIM1, ELIEZER SHALEV3, 1Ha’EmekMedical Center, Ob&Gyn Department, Afula, Israel 2Ha’Emek MedicalCenter, Human Genetic Lab, Afula, Israel 3Technion, Rappaport Faculty ofMedicine, Haifa, Israel

OBJECTIVE: To determine the frequency of thrombophilia among womenwith two unexplained fetal losses.

STUDY DESIGN: A total of 144 women, study to control ratio of 2:1 (96:48),are needed to be screened in order to achieve power of 0.8 and alpha of 0.05,assuming a thrombophilia prevalence of 55% in study subjects and 30% incontrols. All women with two fetal losses in the first or second trimester, in a3-year period, were included. Of 97 women, 19 had at least one 2nd-trimesterfetal loss. Women were excluded from the study if there were chromosomal,anatomic, or endocrine abnormalities. The study group was matched forethnicity with 53 healthy women with a normal obstetrical history. All women, inboth groups were tested for mutations of factor V Leiden, prothrombin gene,MTHFR; for the deficiencies of protein S, protein C, antithrombin III; and forlupus-anticoagulant and anticardiolipin antibodies.

RESULTS: The prevalence of any form of thrombophilia was 43% in thestudy group compared to 32% in the control group (P = 0.22). Inheritedthrombophilia was found in 36% of the study group compared to 21% ofcontrols (P = 0.06). The rate of acquired thrombophilia did not differ betweenthe groups (13% vs 19%, respectively), nor did the rate of combinedthrombophilias (10.3% vs 7.5%). 13 out of 19 (68%) of the women who hadsecond-trimester fetal loss had thrombophilia, a rate significantly higher thanthat of controls (OR 4.59; 95% CI 1.49 to 14.15; P < 0.01) and that of those withfirst-trimester fetal losses (37%) (OR 3.66; 95% CI 1.25 to 10.68; P < 0.02).Absence or existence of previous normal delivery did not change the results.

CONCLUSION: Our findings suggest that a thrombophilia workup isjustified in patients who have had two unexplained fetal losses only if at least oneoccurred during the second trimester.

weeks and birth. A cephalic presenting twin at $28 weeks is very unlikely to benoncephalic at birth, while noncephalic presentation is less stable.

255 INCREASING BODY MASS INDEX RELATED TO FETAL AND MATERNALCOMPLICATIONS ROBERT K. SILVERMAN1, MARTHA WOJTOWYCZ1,JOHN T. NOSOVITCH, JR1, JOHN J. FOLK1, RICHARD H. AUBRY1,1Upstate Medical University, OB/GYN, Syracuse, NY

OBJECTIVE: To use a population-based birth registry to study the statisticalassociation between progressively increasing body mass index (BMI) andmaternal and fetal morbidity.

STUDY DESIGN: We identified 137,580 women who gave birth in centralNew York during 1996-2002. We retrospectively analyzed the associationbetween progressively increasing BMI (not obese [BMI < 29.0], obese [BMI> 29.0 but < 35.0], morbid obesity [BMI $35.0]) and maternal and neonatalcomplications. Maternal medical conditions and complications includedchronic hypertension, chronic lung disease, diabetes mellitus, hospitalizationfor a reason other than the delivery, preeclampsia, cesarean section, uterineatony, chorioamnionitis, and fever. Neonatal complications included low5-minute Apgar scores, meconium aspiration, congenital anomalies, pretermdelivery, and NICU admission. We used chi-square analyses andmultiple logisticregression to determine statistical significance.

RESULTS: We identified 21,121 women as obese and 12,319 as morbidlyobese. These patients were at an increased risk for chronic hypertension (OR2.2, 3.3, respectively, P < .001), chronic lung disease (OR 1.3, 1.4, P < .001),diabetes mellitus (OR 1.6, 2.7, P < .001), preeclampsia (OR 1.9, 2.1, P < .001),and cesarean section (OR 1.7, 2.3, P < .001). We found no significant associationbetween obesity and morbid obesity and uterine atony, chorioamnionitis, andfever. Morbidly obese women were more likely to be hospitalized (OR 1.2,P < .001). Infants of morbidly obese women were more likely to have low Apgarscores at 5 minutes (OR 1.5, P < .001), to have meconium aspiration (OR 1.3,P < .05), to be preterm (OR 1.1, P < .01), and be admitted to a NICU (OR 1.4,P < .001).

CONCLUSION: This large population-based analysis provides strongevidence that excessive maternal BMI is associated with significant maternaland fetal complications. These results argue strongly that BMIs in the obese andmorbidly obese ranges should be independent factors when risk assessinga pregnancy.

Presentation vs gestational age

C/C C/NC NC/C NC/NC

20-23 weeks 13.5% 50.0% 8.0% 28.5%24-27 weeks 25.3% 42.5% 9.7% 22.6%28-31 weeks 29.4% 33.5% 7.2% 29.9%32-36 weeks 40.4% 32.1% 11.4% 16.1%Birth 38.6% 34.8% 8.7% 17.9%