Volume 16.t Number 1, Part 2

240 SIGNIFICANT DIFFERENCES IN CESAREAN BIRTH RATES FOR RESIDENT PHYSICIAN AND NURSE MIDWIFE SERVICES ARE THE RESULT OF SELECTIO!icCRITERIA. Linda Chambliss, M.D., Corne\ia DalytM.D. ,Arnold L. MedeanT~ M.D, Mary_~mes. M.D. ,Ruth urllquist.TC.N.M.x, Martha nR)'1!e

1 C.N.M. ,ana RIchard H. Paul, M.D. UnIVerSIty

of Southern Ca ifornia, LA CA. Our cesarean birth rate (CBR) varies SIgnificantly

between the physician (13%) and the nurse midwife service (2%). The purpose of this study is to investigate this difference and attempt to delineate the reasons. A randomIzed clinical trial was designed and instituted. Sample size needed to demonstrate a stattstically significant difference between a CBR of 2 % and 5 % in a low risk population was 478. Patients were screened m the admitting area to determine, "low risk" eligibility and actual labor. When both units had open beds, patients were randomly admitted to the units with the physicians and midwives unaware of study assignment. Admission criteria included gestational age (GA) > 36 or < 42 completed weeks, GA > 42 completed weeKs with a reactive NST and an amniotic flUid index of> 10 with estimated fetal weight> 2500 grams and < 4000 gram~ low risk class Al diabetes mellitus, previous cesarean sections With documented low transverse scar or an undocumented uterine scar with history of successful or uncomplicated vaginal deliveries. A list of high risk exclusion factors was also used. 490 patients were entered into the study. 254 to the physician service and 236 to the nurse midwife service. Gravidih', parity and estimated fetal weight were not statistically ditlerent oetween the two

groups. N (%) CIS Operative Total Midwife 5 (2.1%) 2 (.9%) 7 (3.0%) Physician 1 (0.4%, 17 ,.<§..7%) 18 (7.1%) There was no statis" , between the CBR for both services in ", < 0.08) There is a statistically sigllifi( erative deliveries (p > 0.002). However, when elective forceps and vacuum deliveries (12) were excluded from the physician service this difference was no longer significant (p < 0.67). We conclude: 1) the CBR rate comparing a physiCIan vs. midwife service is similar in a selected low nsk population, 2) our higher physician service CBR results from the "non low risk" popuTation and 3) a low CBR (2-3%) occurs in a '10w risk" populatIOn.

241 PREINDUCTION CERVICAL RIPENING WITH CONTROLLED-RELEASE POE 2 PESSARY, ~. ~rgX M.L.Yonekura, Division of Maternal-Fetal Medicine, Harbor-UCLA Medical Cenl8r, Torrance, California.

A prospective, randomized, placebo controlled, cross-over study was conduct8d to evaluate the safety and efficacy of a 1omg. dose of PGE 2 (ContRx TM Infusette TM - V, Controlled Therapeutics Corp.), administered in a controlled-release (1 mg.lhr x 10 hrs.) pessary to I8nn patien1S with an unfavorable cervix (Bishop score < 4) 12 hrs. prior to oxytocin induction of labor. The advantage of the current preparation over wax-based suppositories or gel is that it can be removed. Forty-one patien1S were enrolled, 20 in the PGE 2 group, and 21 in the control group. PGE 2 treatment resulted in a significant improvement in the mean Bishop score compared to control (8.11 versus 1.58, P < .001). Similar resuHs were observed in 17 patien1S who were originally in the placebo group and then crossed-over into the PGE 2 group (.53 versus 6.71, P < .001). In addition, 24% (5121) of the patienlS in the PGE 2 group progressed into active labor and delivered in the preinduction period. However, there was no significant difference in the incidence of cesarean section between the two study groups (14 and 30%, respectively in the PGE 2 and controVcrossover groups). Four instances of UlBrine hyperstimulation with the PGE 2 pessary in place, but after the onset of labor resolved with pessary removal and/or subcutaneous terbutatine. We therefore conclude that the controlled-release PGE 2 pessary is a safe and effective cervical priming agent. but it should be removed once a regular labor pattern is established.

SPO Abstracts 313

242 A RANDOMIZED, DOUBLE BLIND TRIAL OF PROSTA­GLANDIN E2 GEL FOR CERVICAL RIPENING AND A META ANALYSIS. J Owen~, CL Winkler, JC Hauth, BA Harrls, MC Smith~. Unlversity of Alabama at Birmingham, Schools of Medicine and Nursing.

The role of prostaglandin E2 (PGE 2 ) gel for cervical ripening and labor inductlon remains controversial. We studied 100 patients who were admitted for labor induction with an unfavorable cervix (modified Bishop score < 5) between 28 and 43 weeks. Each patient was randomly assigned to receive one dose of either intracervical PGE 2 gel, 0.5mg, or an identlcal placebo gel. After a monitored, 12 hour interval, oxytocin was started, unless sponta­neous labor had begun. The 47 women who received the PGE 2 gel were comparable to the 53 control patients with respect to gestational age, parity, initial cervlcal dilatation, and indlcation for delivery. We could demonstrate no benefit from the PGE 2 gel in terms of the incidence of spontaneous labor, duration of labor, cesarean section rate, or f alled induction rate. We also examined 13 other prospective randomized studies which utilized a single dose of at least 5mg of intravaginal or 0.5 mg of intracervical PGE 2 gel. Including our study, the meta analysis included 480 treated and 416 control patients. The cesarean section rate was not improved by the use of PGE 2 gel.

243 PLACENTA PREVIA IS NOT AN INDEPENDENT RISK FACTOR FOR IUGR. Edward J Wolf Angle Mallozzi, John Rod.s, James F.X. Egan, Anthony M. Vlntzileos, Winston A. Campbell, Luanna Lettieri, University of Connecticut Health Center, Farmington, CT.

Prior studies have presented conflicting evidence on the associat.on of intrauterine growth retardation with placenta previa, with some groups reporting rates of IUGR as high as 16·19% However, most of these studies have either failed to include a control population, included patients With other factors known to be assoc.ated with IUGR ( chronic hypertension, fetal anomalies, PIH, Insulin dependent diabetes mellitus, etc.), and/or did not confirm the patient's estimated gestational age. During the study period of January 1,1980 through June 30,1990, 54.969 deliveries occurred at the three hospitals staffed by the MFM diVISion of the University of Connecticut. Review of the delivery records revealed 217 singleton pregnancies diagnosed with placenta previa. Thirty eight patients were excluded from the study because the diagnosis was excluded at the time of delivery, gestational age was not confirmed, or the pregnancy was complicated by other conditions Independently known to be associated With IUGR. One hundred and seventy one of these 179 study patients were compared to 171 patients Without previa matched for confirmed gestational age, race, parity and fetal sex. Eight patients were excluded from the study group because they were unable to be matched for all these factors; none were IUGR. There was no statistical difference between the two groups in height, prepregnancy weight, or weight gain during pregnancy.The inCidence of IUGR (BW<10th%lle) was 4.1% and 5.8% In the study and control group, respectively. Median blrthweights were 2580 and 2466 grams, respectively. Neither difference was statiStically significant. These results suggest that the prenatal diagnosis of IUGR In a pregnancy complicated by placenta previa warrants a search for other etiologies of IUGR, and should not simply be attributed to abnormal placental implantation. Furthermore, routine ultrasonic exams for growth in these pregnancies are not indicated.