387 THE EFFECT OF SMOKING ON MATERNAL THYROID AND ADRENAL FUNCTIONSARAH MCDONALD1, ARNE OHLSSON2, JOSEPH BEYENE3, SHERRY PERKINS4,MARK WALKER5, 1McMaster University, Obstetrics and Gynecology, Hamilton,Ontario, Canada, 2University of Toronto, Pediatrics, Toronto, Ontario, Can-ada, 3Hospital for SickChildren, PopulationHealth Sciences, Toronto,Ontario,Canada, 4University of Ottawa, Biochemistry, Ottawa, Ontario, Canada, 5Uni-versity of Ottawa, Obstetrics and Gynecology, Ottawa, Ontario, Canada

OBJECTIVE: We sought to determine the relationship between smoking andendocrine disruption of maternal thyroid and adrenal function.

STUDY DESIGN: This was a prospective cohort study of 21 smoking and 83non-smoking mothers. One to four matching was selected to reflect theproportion of smokers in our population and also to increase power. Theprimary exposure was self-reported cigarette smoking (dichotomous, ‘‘yes’’ or‘‘no’’). (McDonald, 2005) Healthy women (without endocrine diseases) hadfasting, morning blood samples drawn at term from the antecubital vein usingstandard phlebotomy technique.

RESULTS: Baseline characteristics were similar except for maternal age(smokers were significantly younger, 29.4 C 6.0 years versus 32.6 C 4.3 years,respectively, p=0.030) and the household income and education levels werelower in smokers. TSH levels were significantly lower in smokers than non-smokers (1.8 C0.7 mIU/L versus 2.4 C 1.0 mIU/L, respectively, p=0.012).

CONCLUSION: We demonstrated for the first time during pregnancy to ourknowledge that smokers have lower TSH levels than non-smokers. This non-pregnant literature supports this, with increased risks of Graves disease insmokers, and of ophthalmopathy in Graves patients who smoke. It has beensuggested that the lower TSH levels are due to suppression from glucocorti-coids, which are typically elevated in smokers, although the difference was notstatistically significant in our population. This study provides further evidenceabout the detrimental effects of smoking during pregnancy.

Laboratory values

Mean (SD) in smokers Mean (SD) in non-smokers p value

# cigarettes smoked/day

12.4 (9.4) 0 0.006

Maternal cotinine,ng/mL

96.2 (83.4) 0.1 (0.5) !0.001

Maternal TSH, mIU/L 1.8 (0.7) 2.4 (1.0) 0.012Maternal FT4, pmol/L 9.5 (1.1) 9.7 (1.4) 0.598Maternal cortisol,nmol/L

918 (186) 857 (201) 0.207

388 PRELABOR ESTIMATED FETAL WEIGHT (EFW) - EFFECT ON LABOR MANAGEMENTYAEL MELAMED YEKEL1, AHARON TEVET1, RENAT REENS1, RONIT CALDERON-MAR-GALIT2, EFRAIM GDANSKI1, SORINA GRISARU-GRANOVSKY1, MICHAEL SHAYA1,ARTHUR I. EIDELMAN3, ARNON SAMUELOFF1, 1Shaare Zedek Medical Center af-filiated with Ben-Gurion University of the Negev, Obstetrics and Gynecology,Jerusalem, Israel, 2Hebrew University of Jerusalem, Hadassah School of Pub-lic Health, Jerusalem, Israel, 3Shaare Zedek Medical Center affiliated withBen-Gurion University of the Negev, Pediatrics, Jerusalem, Israel

OBJECTIVE: To evaluate the effect of predelivery EFW on labor manage-ment of nulliparas with a macrosomic fetus (O4 kg).

STUDY DESIGN: Nulliparas that delivered babies 4 kg, were dividedaccording to the predelivery EFW into macrosomic (O4 kg) (Group 1) andEFW !4 kg (Group 2). Predelivery clinical and ultrasonic EFW, mode ofdelivery and postpartum complications were compared. Parturients withsuspected macrosomic fetuses were allowed to proceed into a trial of labor(TOL) if EFW !4.5 Kg, singleton, head presentation and not diabetic.

RESULTS: 189 of 221 nulliparous (86%) received TOL and had at least oneprelabor EFW, either clinical (Group 1 – n=62, Group 2 – n= 79) orultrasonic (Group 1 – n=64, Group 2 – n=65). The actual birth weight inGroup 1 and 2 were similar. However, the Cesarean section rate in Group1 according to clinical estimation was significantly increased over Group 2(17% vs. 8% p!0.026). Ultrasound estimations did not correlate to the modeof delivery (p !0.11). Post partum complications rate did not differ betweenthe cesarean deliveries and the VD for both groups. Neonates in both groupsdid well and had null perinatal mortality. Four cases of shoulder dystocia werereported, two cases in each group.

CONCLUSION: Prelabor clinical estimate of birth weight, biases clinicalmanagement of a trial of labor in nulliparas with fetuses who are potentiallymacrosomic. In situations when fetuses were estimated to be less than 4.0 kgthere was less medical intervention even though in reality such fetuses were nodifferent in actual birth as compared to those estimated to weigh more. Thus,such trials of labor should be unbiased by prenatal estimate of weight andshould be managed only on objective obstetric criteria. Clinical and ultrasonicestimates proved to be a poor predictor for birth weight.

389 DOES PRENATAL CARE INFLUENCE DOWN SYNDROME LIVEBIRTHS? BRUCEMORRIS (F)1, JAMES EGAN1, HENRY ROQUE1, MARY BETH JANICKI1, VICTORFANG1, WINSTON CAMPBELL1, 1University of Connecticut, Obstetrics and Gyne-cology, Farmington, Connecticut

OBJECTIVE: From 1989 to 2001 reported Down syndrome (DS) livebirthsdecreased while the mean maternal age increased. DS screening has contributedto this reduction. We chose to evaluate whether the adequacy of prenatal careaffects the number of DS livebirths as measured by the Kessner index.

STUDY DESIGN: Using National Center for Health Statistics Data for 2001recorded maternal age-specific DS livebirths were stratified into livebirths towomen 15-34 and 35-49 years old and compared to a baseline of livebirths towomen 15-34 in 1989. Age-specific maternal livebirths were multiplied by age-specific DS risk to estimate the number of DS livebirths. We assumed no changein accuracy of birth certificate reporting of DS. Percent reduction from baselineof DS livebirths was calculated for the two age groups and stratified accordingto Kessner criteria for adequacy of prenatal care (adequate, intermediate,inadequate, timing of first visit, number of visits, and gestational length).

RESULTS: There were a total of 3,954,271 deliveries in our study group. Aminimum 30% reduction was seen in every group (Fig. 1). The largestreduction occurred among thoseR35 years old with little difference seen in the!35 year old age groups.

CONCLUSION: Adequacy of prenatal care as reflected by the Kessner indexdoes not affect DS livebirths for women !35 years old but does affect DSlivebirths for women R35 years old.

390 HUMAN CHORIONIC GONADOTROPIN LEVELS FOLLOWING SPONTANEOUS ABOR-TION IN THE FIRST TRIMESTER NDAYA MULEBA (F)1, BRIAN CASEY1, C. EDWARDWELLS1, DONALD MCINTIRE1, KENNETH LEVENO1, 1University of Texas South-western Medical Center at Dallas, Obstetrics and Gynecology, Dallas, Texas

OBJECTIVE: To determine the rate of human chorionic gonadotropin (hCG)decline in women with spontaneous resolution of early pregnancy failure.

STUDY DESIGN: This is an observational study of women who presentedbetween September 2002 and June 2005 with vaginal bleeding during the firsttrimester and subsequently identifiedwith early pregnancy failure. These womenwere followed at least every two weeks in a special obstetrics clinic and serumhCG levels were drawn at each visit. Women with spontaneous resolutionwithout medical or surgical intervention were included in this analysis. Spon-taneous resolution was defined as a hCG level of 10 mIU/mL or less. Linearregression was applied to determine the slope of the natural logarithm of thehCG levels of each patient to the number of days from identification. Summarystatistics were computed for these slopes to determine the mean and percentiles.

RESULTS: During the study period, 1,371 women were identified withspontaneous resolution of an early pregnancy failure and 1,152 (84%) had twoor more quantitative hCG levels. The median time from identification tospontaneous resolution was 21 days [interquartile range: 14, 29]. Linesrepresenting the mean and 95th percentile decline in hCG are depicted below.

CONCLUSION: In women with successful spontaneous resolution of earlypregnancy failure, hCG levels declined on average by 50% every two days.Human chorionic gonadotropin levels declined by half within 7 days in over 95% of women managed expectantly.

S116 SMFM Abstracts