late pregnancy termination for fetal anomaly

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592 PROGRESSIVE HEMODYNAMIC AND ACID-BASE ALTERATIONS IN AN OVINE MODEL OF IUGR OF DIFFERENT SEVERITY HENRY L. GALAN 1 , BARBRA DEVRIJER 2 , ALESSANDRA PADOAN 3 , ENRICO FERRAZZI 3 , RUSSELL V. ANTHONY 4 , RANDALL B. WILKENING 4 , TIMOTHY R.H. REGNAULT 4 , 1 University of Colorado Health Sciences Center, Obstetrics & Gynecology, Denver, CO 2 Erasmus University Medical Centre, Obstetrics & Gynecology, Rotterdam, The Netherlands 3 University of Milan, Obstetrics & Gynecology, Milan, Italy 4 University of Colorado Health Sciences Center, Pediatrics, Aurora, CO OBJECTIVE: Hyperthermia (HT) in ovine pregnancy raises core body temperature (CBT) and induces severe IUGR if the CBT response is rapid (HT- R) or intermediate IUGR (HT-I) if the CBT rise is slow. The aim of the study was to compare hemodynamic and acid-base values among control, HT-R, and HT-I sheep. STUDY DESIGN: 12 pregnant ewes exposed to HT from 35-115 days’ gestation (dGA) resulted in 8 HT-R and 4 HT-I ewes. These and 8 control ewes had an umbilical artery (UA) Doppler (S/D ratio) exam and fetal aortic catheter placement prior to sacrifice at 135 dGA. Fetal endpoints were compared among the 3 groups with regression and ANOVA: fetal weight, S/D ratio, heart rate (HR), blood pressure (BP), and UA gases. RESULTS: See Table below. No differences were found for HR, pCO 2 , or Hgb. S/D ratio changes showed a continuous and significant increase with decreasing weight. BP, pH, pCO 2 , & SaO 2 in control and HT-I were similar, but both were different from HT-R. An inflection point was detected at 2000 g, below which these values drop precipitously. CONCLUSION: UA Doppler shows that vascular changes occur continu- ously across groups, while gas tensions remain stable until about < 2000 g, at which point there is impending vascular collapse. 593 MOTHER’S OWN BIRTH WEIGHT INFLUENCES THE RATE OF SMALL- FOR-GESTATIONAL-AGE BIRTHS: AN ANALYSIS BY MATERNAL BODY MASS INDEX JOHN SMULIAN 1 , CANDE ANANTH 1 , WENDY KINZLER 1 , SUSAN LASHLEY 1 , ANTHONY VINTZILEOS 1 , 1 UMDNJ-Robert Wood Johnson Medical School/Robert Wood Johnson University Hospital, Obstet- rics, Gynecology and Reproductive Sciences, New Brunswick, NJ OBJECTIVE: Individuals with low birth weight, especially when small for gestational age (SGA), can have altered postnatal growth that may be due to metabolic reprogramming. Women born small due to SGA are also at risk for delivering an SGA infant themselves. This study tests the hypothesis that mother’s own birth weight (BW) influences the rate of SGA births but that this effect is modified by maternal body mass index (BMI). STUDY DESIGN: Liveborn singleton data from the National Maternal and Infant Health Survey including mother’s BW and detailed pregnancy outcome information were used. The data were collected in 1988 using sampling techniques that allow extrapolation of findings to the general U.S. population by weighted analyses. Rates for SGA births ( < 10th centile for 1988 births) were stratified by mother’s BW across BMI categories of < 20 (underweight), 20-24.9 (normal), 25-29.9 (overweight), and $30 (obese) after adjusting for weighted sampling. RESULTS: Out of 6744 births in the sample, there were 1243 SGA infants. This corresponds to a weighted population sample of 2,972,894 births and an SGA rate of 9.1%. SGA rates stratified on mother’s BW and BMI at delivery are presented in the Table. CONCLUSION: Lower maternal BW is associated with higher SGA rates for all BMI categories except for BW < 1500 g, which likely reflects more preterm rather than SGA births. However, extremes of BMI (underweight and overweight) have the highest rates of SGA birth across almost all maternal BW strata. These data suggest the possibility that maternal BW effects on pregnancy outcomes such as SGA births may be dependent on the maternal metabolic status as reflected by BMI. 594 NORMAL RANGES FOR FETAL LUNG VOLUME MEASURED BY 3- DIMENSIONAL ULTRASOUND FRANCA GERARDS 1 , JOS TWISK 2 , JOHN M.G. VUGT 1 , 1 VU Medical Center, Obstetrics and Gynaecology, Amsterdam, North Holland, Netherlands 2 VU Medical Center, Biostatistics, Amsterdam, North Holland, Netherlands OBJECTIVE: To determine the normal lung volume ranges by 3- dimensional ultrasound in the second and third trimesters of pregnancy. STUDY DESIGN: In 15 uncomplicated pregnancies with certain gestational ages between 18 and 34 weeks, four ultrasound examinations were performed with an interval of 4 weeks. Images were acquired by moving the transducer in a transverse plane from the fetal neck to below the level of the diaphragm. A transmitter and receiver connected to the ultrasound machine measured the position and orientation of the transducer. The outlines of the lungs, thorax, and heart were highlighted. To standardize the measurements, an upper anatomical limit at the level of the fetal clavicles and a lower limit at the dome of the diaphragm were set. From these 2D outlines, 3D models were rendered. Each measurement was repeated three times. The formula used for the volume calculation was: Volume = Sum of all drawn contours of vol i; vol i = Distance i * (A + Sqrt (A*B) + B)/3; A = Area of contour-1, B = Area of contour-2, distance i is the distance between the slices where the contour was drawn. RESULTS: The mean lung volume increase was calculated using linear regression analysis. The right lung volume increased with 2.58 ± 0.46 mL/wk; the left lung, 1.60 ± 0.26 mL/wk; the thorax, 6.57 ± 1.04 mL/wk; the heart, 1.02 ± 0.15 mL/wk; and the average total lung volume, with 4.55 ± 0.72 mL/ wk. The intraclass correlation coefficient of all measurements was >0.99. CONCLUSION: This study shows that 3-dimensional ultrasound allows determination of the normal range of fetal lung growth. These normal values may be of importance in cases in which lung hypoplasia is suspected. 595 LATE PREGNANCY TERMINATION FOR FETAL ANOMALY JAN E. DICKINSON 1 , 1 The University of Western Australia, School of Women’s and Infants’ Health, Perth, Western Australia, Australia OBJECTIVE: To review the indications and outcomes for abortion beyond 20 weeks’ gestation within an environment of legislated notifiable pregnancy termination. STUDY DESIGN: In Western Australia legislation allowing abortion >20 weeks’ gestation for serious maternal-fetal conditions was enacted in May 1998. Late abortions are only permitted in a single state institution and notifiable by law. All pregnancy terminations >20 weeks’ gestation performed since this legislation were prospectively identified with the indications and outcomes reviewed. RESULTS: During the study period 201 women underwent abortion >20 weeks’ gestation. This group represented 0.37% of all abortions in the state. Comparison with 427 contemporaneous medical abortions for fetal anomaly at 14-20 weeks’ gestations is shown in the Table. Misoprostol was the primary abortifacient for both. The principal indications for abortions >20 weeks were karyotypic (28.3%), cerebrospinal (23.1%), and cardiac (15.1%) anomalies. Cardiac anomalies represented 3.1% of fetal anomaly terminations at 14-20 weeks (P < 0.01). 11.3% of abortions were performed at gestations beyond 24 weeks, with feticide used for all non-lethal anomalies. CONCLUSION: Abortion >20 weeks’ gestation under medically regulated legislation is used primarily for serious fetal anomalies. The women are younger and the abortion duration is greater than at earlier gestations. Control HT-I HT-R P Value Fet. wt. (g) 3617 ± 592* 2986 ± 285* 1690 ± 559* < 0.003 BP (torr) 43 ± 2.3 49 ± 1.1 51 ± 0.6* < 0.03 pH 7.36 ± 0.02 7.37 ± 0.01 7.30 ± 0.07 0.06 SaO 2 46.0 ± 5.1 44.4 ± 14.0 19.2 ± 11.5* < 0.008 SGA rates (per 100 live births) by maternal BW and BMI Maternal BMI BW (g) < 20 20-24.9 25-29.9 $30 < 1500 19.3 9.9 6.7 2.7 1500-2499 20.5 17.6 12.4 12.7 2500-2999 13.8 10.6 10.2 17.0 3000-3499 10.6 5.6 7.1 8.6 3500-3999 9.5 4.8 5.9 9.5 $4000 4.8 2.2 1.3 7.6 14-20 weeks (n = 427) >20 weeks (n = 201) P value Maternal age (years) 32 (27,36) 29 (25,34) < 0.001 Parity 1 (0,2) 1 (0,2) 0.76 Prenatal karyotype 67.5% 61.3% 0.14 Duration (hours) 15.7 (11.5,23.4) 18.4 (14,26.9) 0.001 Placental retention 42.9% 8.6% < 0.001 Blood loss (mL) 100 (50,150) 100 (50,200) 0.13 Transfusion 2.8% 0.5% 0.11 Volume 189, Number 6 Am J Obstet Gynecol SMFM Abstracts S221

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Page 1: Late pregnancy termination for fetal anomaly

592 PROGRESSIVE HEMODYNAMIC AND ACID-BASE ALTERATIONS IN ANOVINE MODEL OF IUGR OF DIFFERENT SEVERITY HENRY L. GALAN1,BARBRA DEVRIJER2, ALESSANDRA PADOAN3, ENRICO FERRAZZI3,RUSSELL V. ANTHONY4, RANDALL B. WILKENING4, TIMOTHY R.H.REGNAULT4, 1University of Colorado Health Sciences Center, Obstetrics &Gynecology, Denver, CO 2Erasmus University Medical Centre, Obstetrics &Gynecology, Rotterdam, The Netherlands 3University of Milan, Obstetrics &Gynecology, Milan, Italy 4University of Colorado Health Sciences Center,Pediatrics, Aurora, CO

OBJECTIVE: Hyperthermia (HT) in ovine pregnancy raises core bodytemperature (CBT) and induces severe IUGR if the CBT response is rapid (HT-R) or intermediate IUGR (HT-I) if the CBTrise is slow. The aim of the study wasto compare hemodynamic and acid-base values among control, HT-R, and HT-Isheep.

STUDY DESIGN: 12 pregnant ewes exposed to HT from 35-115 days’gestation (dGA) resulted in 8 HT-R and 4 HT-I ewes. These and 8 control eweshad an umbilical artery (UA)Doppler (S/D ratio) exam and fetal aortic catheterplacement prior to sacrifice at 135 dGA. Fetal endpoints were compared amongthe 3 groups with regression and ANOVA: fetal weight, S/D ratio, heart rate(HR), blood pressure (BP), and UA gases.

RESULTS: See Table below. No differences were found for HR, pCO2, orHgb. S/D ratio changes showed a continuous and significant increase withdecreasing weight. BP, pH, pCO2, & SaO2 in control and HT-I were similar, butboth were different fromHT-R. An inflection point was detected at 2000 g, belowwhich these values drop precipitously.

CONCLUSION: UA Doppler shows that vascular changes occur continu-ously across groups, while gas tensions remain stable until about < 2000 g, atwhich point there is impending vascular collapse.

593 MOTHER’S OWN BIRTH WEIGHT INFLUENCES THE RATE OF SMALL-FOR-GESTATIONAL-AGE BIRTHS: AN ANALYSIS BY MATERNAL BODYMASS INDEX JOHN SMULIAN1, CANDE ANANTH1, WENDY KINZLER1,SUSAN LASHLEY1, ANTHONY VINTZILEOS1, 1UMDNJ-Robert WoodJohnson Medical School/Robert Wood Johnson University Hospital, Obstet-rics, Gynecology and Reproductive Sciences, New Brunswick, NJ

OBJECTIVE: Individuals with low birth weight, especially when small forgestational age (SGA), can have altered postnatal growth that may be due tometabolic reprogramming. Women born small due to SGA are also at risk fordelivering an SGA infant themselves. This study tests the hypothesis thatmother’s own birth weight (BW) influences the rate of SGA births but that thiseffect is modified by maternal body mass index (BMI).

STUDY DESIGN: Liveborn singleton data from the National Maternal andInfant Health Survey including mother’s BW and detailed pregnancy outcomeinformation were used. The data were collected in 1988 using samplingtechniques that allow extrapolation of findings to the general U.S. population byweighted analyses. Rates for SGA births ( < 10th centile for 1988 births) werestratified by mother’s BW across BMI categories of < 20 (underweight), 20-24.9(normal), 25-29.9 (overweight), and $30 (obese) after adjusting for weightedsampling.

RESULTS: Out of 6744 births in the sample, there were 1243 SGA infants.This corresponds to a weighted population sample of 2,972,894 births and anSGA rate of 9.1%. SGA rates stratified on mother’s BW and BMI at delivery arepresented in the Table.

CONCLUSION: Lower maternal BW is associated with higher SGA rates forall BMI categories except for BW < 1500 g, which likely reflects more pretermrather than SGA births. However, extremes of BMI (underweight andoverweight) have the highest rates of SGA birth across almost all maternal BWstrata. These data suggest the possibility that maternal BW effects on pregnancyoutcomes such as SGA births may be dependent on the maternal metabolicstatus as reflected by BMI.

594 NORMAL RANGES FOR FETAL LUNG VOLUME MEASURED BY 3-DIMENSIONAL ULTRASOUND FRANCA GERARDS1, JOS TWISK2, JOHNM.G. VUGT1, 1VU Medical Center, Obstetrics and Gynaecology, Amsterdam,North Holland, Netherlands 2VU Medical Center, Biostatistics, Amsterdam,North Holland, Netherlands

OBJECTIVE: To determine the normal lung volume ranges by 3-dimensional ultrasound in the second and third trimesters of pregnancy.

STUDY DESIGN: In 15 uncomplicated pregnancies with certain gestationalages between 18 and 34 weeks, four ultrasound examinations were performedwith an interval of 4 weeks. Images were acquired by moving the transducer ina transverse plane from the fetal neck to below the level of the diaphragm. Atransmitter and receiver connected to the ultrasound machine measured theposition and orientation of the transducer. The outlines of the lungs, thorax,and heart were highlighted. To standardize the measurements, an upperanatomical limit at the level of the fetal clavicles and a lower limit at the dome ofthe diaphragm were set. From these 2D outlines, 3D models were rendered.Each measurement was repeated three times. The formula used for the volumecalculation was:

Volume = Sum of all drawn contours of vol i; vol i = Distance i * (A + Sqrt(A*B) + B)/3; A = Area of contour-1, B = Area of contour-2, distance i is thedistance between the slices where the contour was drawn.

RESULTS: The mean lung volume increase was calculated using linearregression analysis. The right lung volume increased with 2.58 ± 0.46 mL/wk;the left lung, 1.60 ± 0.26 mL/wk; the thorax, 6.57 ± 1.04 mL/wk; the heart,1.02 ± 0.15 mL/wk; and the average total lung volume, with 4.55 ± 0.72 mL/wk. The intraclass correlation coefficient of all measurements was >0.99.

CONCLUSION: This study shows that 3-dimensional ultrasound allowsdetermination of the normal range of fetal lung growth. These normal valuesmay be of importance in cases in which lung hypoplasia is suspected.

595

Control HT-I HT-R P Value

Fet. wt. (g) 3617 ± 592* 2986 ± 285* 1690 ± 559* < 0.003BP (torr) 43 ± 2.3 49 ± 1.1 51 ± 0.6* < 0.03pH 7.36 ± 0.02 7.37 ± 0.01 7.30 ± 0.07 0.06SaO2 46.0 ± 5.1 44.4 ± 14.0 19.2 ± 11.5* < 0.008

SGA rates (per 100 live births) by maternal BW and BMI

Maternal BMI

BW (g) < 20 20-24.9 25-29.9 $30<1500 19.3 9.9 6.7 2.71500-2499 20.5 17.6 12.4 12.72500-2999 13.8 10.6 10.2 17.03000-3499 10.6 5.6 7.1 8.63500-3999 9.5 4.8 5.9 9.5$4000 4.8 2.2 1.3 7.6

Volume 189, Number 6Am J Obstet Gynecol

SMFM Abstracts S221

LATE PREGNANCY TERMINATION FOR FETAL ANOMALY JAN E.DICKINSON1, 1The University of Western Australia, School of Women’sand Infants’ Health, Perth, Western Australia, Australia

OBJECTIVE: To review the indications and outcomes for abortion beyond20 weeks’ gestation within an environment of legislated notifiable pregnancytermination.

STUDY DESIGN: In Western Australia legislation allowing abortion >20weeks’ gestation for serious maternal-fetal conditions was enacted in May 1998.Late abortions are only permitted in a single state institution and notifiable bylaw. All pregnancy terminations >20 weeks’ gestation performed since thislegislation were prospectively identified with the indications and outcomesreviewed.

RESULTS: During the study period 201 women underwent abortion >20weeks’ gestation. This group represented 0.37% of all abortions in the state.Comparison with 427 contemporaneous medical abortions for fetal anomaly at14-20 weeks’ gestations is shown in the Table. Misoprostol was the primaryabortifacient for both. The principal indications for abortions >20 weeks werekaryotypic (28.3%), cerebrospinal (23.1%), and cardiac (15.1%) anomalies.Cardiac anomalies represented 3.1% of fetal anomaly terminations at 14-20weeks (P < 0.01). 11.3% of abortions were performed at gestations beyond 24weeks, with feticide used for all non-lethal anomalies.

CONCLUSION: Abortion >20 weeks’ gestation under medically regulatedlegislation is used primarily for serious fetal anomalies. The women are youngerand the abortion duration is greater than at earlier gestations.

14-20 weeks(n = 427)

>20 weeks(n = 201) P value

Maternal age (years) 32 (27,36) 29 (25,34) < 0.001Parity 1 (0,2) 1 (0,2) 0.76Prenatal karyotype 67.5% 61.3% 0.14Duration (hours) 15.7 (11.5,23.4) 18.4 (14,26.9) 0.001Placental retention 42.9% 8.6% <0.001Blood loss (mL) 100 (50,150) 100 (50,200) 0.13Transfusion 2.8% 0.5% 0.11