410 SPO Abstracts

599 FETAL DEATH RISK. Myers, S.A., Ferguson, RX. Mt. Sinai Hosp., IL. Dept. Pub. Hlth., Chicago. Previous work has shown that birthweight (BWT) centile does not consistently predict fetal death (FD) and that black fetuses are more sensitive to altered growth (AG) (SPO, 1989). Also, population based risk, calculated based upon fetuses remaining (FDR/1000 R) represents true estimate of FD risk (SPO, 1990). As a result, we examined the simultaneous relation­ship between BW, GA and FDR/1000 R for both white and black races. Using the Illinois computer data we examined 550,559 white and 159,603 black births from 1984-88. For each race, mean BWT and BWT FDR4 (4x modal FDR) was determined. True FD r~~k for each 200 g BW cohort was determined (FD/births + est. remaining fetuses in each cohort) allowing the construction of figures simultaneously representing GA, BWT and FD risk. We conclude: 1) the centile-specific risk of FD is constant prior to 38 wks. GA, with the risk for black fetuses 2-3 times higher, 2) term AGA fetuses of both races have comparable FD risks to fetuses with AG prior to 38 wks. These data suggest that surveillance be directed to black fetuses prior to 38 wks. GA and fetuses of both races at term.

600 RECENT TRENDS IN MATERNAL DRINKING FOR AN INNER CITY CLINIC POPULATION

J Ager,X S Martier,X J Sloan,x J Hankin,x I Firestonex and R Sokol Wayne State Univ/Hutzel Hospital, Detroit, MI

Overall consumption of alcohol intake in the United States has decreased over the past few years, but the impact, if any, of public information campaigns, covering alcohol-related pregnancy risk, on maternal drinking must has not been reported. To look at recent trends in maternal drinking for our inner city black prenatal clinic population, alcohol measures were obtained from 5762 consecutive gravidas. These measures included average absolute alcohol per day around the time of conception (aad) , proportion drinking days (pdd) and MAST (Michigan Alcoholism Screening Test). For each of 131 consecutive weeks from September, 1986 through mid-March 1989, mean and 90th %ile aad, mean and 90th %ile pdd, and proportion abstainers and MAST positives (~ 5) were obtained. An ARIMA time series analysis done on each measure revealed no evidence of a decrease in maternal drinking for the aad and pdd measures over this period; for the MAST measures there was evidence of an increase in numbers of women who drank. Thus, there is no evidence for decreased drinking or heavy drinking or for decreased embryonic/fetal alcohol exposure. The time series will be extended for the next 3 years to evaluate if there are effects attributable to the new liquor labelling law instituted in November, 1989.

JanUdr), lY91 Am J Obstet G}necol

601 CESAREAN SECTION RATES SHOULD BE ADJUSTED FOR PATIENT PARtlY AND AGE !

AGrunebaum.MD.St.Luke's\Roosevelt He,New York,NY New York State has recently implemented that individual

hospital's cesarean section rates are made public to patients. Recent published data have shown that significant differences in cesarean section rates exist between individual hospitals. MATERIALS & METHODS: This study comprises a total of 9,647 consecutive deliveries over 2 years at a voluntary inner­city hospital. The overall primary cesarean section rate was 17.9%, and for individual patient groups it was was 22.3% (PRIVATE), 16.1% (CLINIC), and 10.3% (NO CARE) (p<O.OOI).

RELATIVE RISK OF PRIMARY CESAREAN SECTION BY PARIlY. AGE. AND STATUS

PARA/AGE PRlV. CUN. NO CARE P Mul{i<30 .54 .44 .42 NS Multi> ;30 .77 .79 .54 NS Primi<30 1.52 1.26 .81 <.01 Primi> ;30 2.20 1.92 2.02 NS

CONCLUSIONS: 1.Except for primigravida under 30 years of age there were no significant differences in CIS rates among patients with different levels of prenatal care. 2.Comparisons of CIS rates among different hospitals and populations are incomplete unless patients' characteristics such as parity and age are taken into consideration.

602 TRIAL OF LABOR AFTER A ONE OR TWO LAYER CLOSURE OF A LOW TRANSVERSE UTERINE INCISION JM Tucker, JC Hauth, CL Winkler, J Owen:lf M Dubard. Divis~on of Maternal-Fetal Medicine, University of Alabama at Birmingham, Alabama.

Vaginal birth is commonly attempted after a prior low cervical transverse cesarean inc~slon. However, there is little documen­tation of the safety of post-cesarean vaginal birth with respect to a one or two layer uterine incision closure. We reviewed the charts of all women ( 134) who had a low transverse cesarean section with no vertical extensions and had a subsequent labor and delivery in our unit between January 1, 1987 and February 14, 1990. In 51 women the uterine incision was closed in one continuous suture layer and in 83 it was closed in two continuous layers. Maternal morbidity and neonatal outcomes were similar in both groups during the subsequent pregnancy and delivery. There were two asymptomatic uterine scar separations in each group. We conclude that closure of a transverse uterine incision in one continuous suture layer should not preclude a trial of vaginal birth after low cervical cesarean section.