336 PRE-PREGNANCY BODY MASS INDEX AND LENGTH OF GESTATION AT TERMNAOMI STOTLAND1, A. EUGENE WASHINGTON1, AARON CAUGHEY1, 1University ofCalifornia, San Francisco, Department of Obstetrics, Gynecology and Repro-ductive Sciences, San Francisco, California

OBJECTIVE: To examine the relationship between pre-pregnancy body massindex (BMI) and length of gestation at term.

STUDY DESIGN: This was a retrospective study of 10,878 parturients. Weexcluded preterm births, multiple gestations, and elective cesareans withoutlabor. We performed univariate and multivariate analyses of the associationsbetween pre-pregnancy BMI and length of gestation (O40 weeks, O41 weeks,and O42 weeks).

RESULTS: Overweight women were more likely to deliver at O40 weeks,O41 weeks, and O42 weeks than women who were underweight or normalweight (Table 1). In multivariate analyses, higher pre-pregnancy BMI (as acontinuous variable) was associated with longer length of gestation at term.Obese women had a 30% higher adjusted odds of reaching 42 weeks gestationcompared to women of normal pre-pregnancy BMI (adjusted odds ratio 1.30,95% CI 1.08-1.57) (Table 2).

CONCLUSION: Higher BMI is associated with longer gestation at term.Despite the fact that higher BMI is associated with gestational diabetes andhypertension, conditions that frequently require delivery prior to 40 weeksgestation, overweight women were more likely to go past their estimated duedate. Achieving a healthy BMI prior to conception may reduce the risk ofpostterm pregnancy and its associated complications.

Table 1. Pre-pregnancy BMI and length of gestation at term

Low BMI Normal BMI High BMI Obese BMI p-value

GA O40 weeks 50.9% 52.5% 53.0% 57.0%GA O41 weeks 19.8% 23.1% 24.75% 29.0%GA O42 weeks 3.4% 4.7% 6.1% 5.7%

Table 2. Multivariate analysis of pre-pregnancy BMI and length of term

gestation

Low BMI Normal BMI High BMI Obese BMI

GA O40 weeks 0.95 (0.89-1.01) Reference 1.08 (0.99-1.18) 1.31 (1.19-1.46)GA O41 weeks 0.83 (0.77-0.89) Reference 1.19 (1.08-1.32) 1.39 (1.24-1.57)GA O42 weeks 0.77 (0.68-0.87) Reference 1.24 (1.06-1.46) 1.30 (1.08-1.57)

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.366

337 PATTERNS OF PHYSICAL AND SEXUAL ACTIVITY IN PRIMIGRAVIDAS.NATHAN FOX1, STEPHEN CHASEN1, 1Weill Medical College of Cornell University,Obstetrics/Gynecology, New York, New York

OBJECTIVE: There is a paucity of published data describing patterns ofphysical and sexual activity in pregnant patients, especially at the end ofpregnancy. Our objective was to survey women about their activity duringpregnancy.

STUDY DESIGN: Questionnaire-based anonymous survey of women duringthe immediate postpartum period. Women who delivered their 1st child andwere inpatients on our postpartum unit were eligible for inclusion. Womenwere asked to recall their levels of physical and sexual activity during the thirdtrimester, during the 2 weeks prior to delivery and during the 2 days prior todelivery.

RESULTS: 585 women were surveyed, 323 (55%) returned the question-naire. Mean maternal age was 32 C/�5 years. Mean GA at delivery was 39 4/7weeks C/�9 days. 74.3% of women reported being on their feet 5 or morehours/day in the third trimester. 56.4% reported similar activity during the 2days prior to delivery. 50.2% reported performing strenuous physical activity(‘‘working-out’’) at least every week during the third trimester. 36.5% did so inthe 2 days prior to delivery. 22.9% and 26.6% reported having intercourse andorgasm, respectively, at least every week during the third trimester. 16.6% and18.8%, respectively, reported such activity during the 2 days prior to delivery.The frequency of intercourse and orgasm during the third trimester was equalfor only 68.1% of patients. 13.6% reported more intercourse than orgasms;15.5% reported more orgasms than intercourse. During the 2 days prior todelivery the frequency of intercourse and orgasm was equal for 85.1%. 5.6%reported more intercourse than orgasms; 7.7% reported more orgasms thanintercourse.

CONCLUSION: Physical and sexual activity is very common amongstprimigravidas in the third trimester and continuing until labor. This includeshaving orgasms apart from intercourse.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.367

338 MATERNAL ACTIVITY DURING PREGNANCY AND INTRAPARTUM CESAREANSECTION RATES: ARE THEY ASSOCIATED? NATHAN FOX1, STEPHEN CHASEN1,1Weill Medical College of Cornell University, Obstetrics/Gynecology, NewYork, New York

OBJECTIVE: To search for an association between maternal physical andsexual activity during pregnancy and intrapartum CS rates.

STUDY DESIGN: Questionnaire-based anonymous survey of women duringthe immediate postpartum period. Women who delivered their 1st child andwere inpatients on our postpartum unit were eligible for inclusion. Womenwere asked details of their delivery and asked to recall their levels of physicaland sexual activity during three separate time periods: the third trimester, the2 weeks prior to delivery and the 2 days prior to delivery. Women who had anelective CS before labor were excluded.

RESULTS: 585 women were surveyed, 323 (55%) returned the question-naire. 36 patients reported a CS before labor and were excluded leaving 287patients. Mean age was 31 +/�5 years and mean GA at delivery was 39 4/7weeks +/�9 days. The CS rate was 32.6%. 188 patients (65.3%) reportedspontaneous labor and their CS rate was 28.7%. 100 patients (34.7%) reportedinduction of labor and their CS rate was 40%. For those who went intospontaneous labor, increased daily activity (O9hours/day on feet) in the thirdtrimester was associated with a decreased CS rate (16% vs. 35%, p=.007).However, physical and sexual activity in the 2 days and 2 weeks prior to laborwas not associated with CS rate. For those patients with induced labor,increased physical and sexual activity in any of the time periods were notassociated with CS rate.

CONCLUSION: Increased daily activity in the third trimester is associatedwith a lower CS rate in those patients who go into spontaneous labor.Increased sexual activity or strenuous physical activity prior to induction oflabor or prior to spontaneous labor does not change the rate of CS.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.368

339 HEAD-TO-BODY INTERVAL TIME: WHATIS THE NORMAL RANGE? NICOLA STROBELT1,ANNA LOCATELLI1, GIOVANNA CASARICO1, SIMONA FERRINI1, MARTINA BONASSERA1,ANNA LONGONI1, MADDALENA INCERTI1, 1University of Milano-Bicocca, Obstetricsand Gynecology, Monza, Italy

OBJECTIVE: In Institutions utilizing the one-step approach to delivery ofthe body (i.e. applying traction immediately after delivery of the head toaccomplish delivery of the body) it has been proposed that a head-to-bodyinterval O60 sec be used for definition of shoulder dystocia (Spong Ob Gyn1995), as it correspond to O2 SD above the mean interval . In EuropeanInstitutions such as ours assistance to vaginal delivery utilizes a ‘‘two-step’’approach, i.e. waiting for subsequent contractions if the shoulders are notdelivered after expulsion of the head before applying traction. We haveprospectively recorded the head-to-body delivery interval using such approachto establish the normality range and to evaluate its effect on rates of shoulderdystocia.

STUDY DESIGN: Prospective observational study on all singleton termvaginal deliveries during the period June-December 2005. Duration of thephases of labor, time interval between delivery of the head and the body,number of contractions after delivery of the head, and mode of delivery wereprospectively collected. Shoulder dystocia was defined as the need for ancillarymaneuvers to facilitate delivery of the shoulders.

RESULTS: In the 789 cases of the cohort mean second stage duration was32G22 min. In 33 cases (4%) the body was delivered 2 or more contractionsafter delivery of the head. Mean head-to-body delivery interval was 88G61sec, and it lasted O60 sec in 495 cases (63%). Operative vaginal delivery wasrequired in 20 cases (2.5%). Shoulder dystocia occurred in only 2 cases(0.25%). Mean birth-weight was 3292G 416 and only 1 neonate (0.1%) had anApgar score at 5 min !7.

CONCLUSION: A ‘‘two-step’’ approach to vaginal delivery leads to a head-to-body delivery time interval longer than previously reported but results in alower rate of shoulder dystocia than reported in case series utilizing otherapproaches to delivery of the body.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.369

S110 SMFM Abstracts