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308 Stereological analysis of human myometriumn third trimester pregnancy: influence of

aternal age, body mass index and parityEva Sweeney2, Denis Crankshaw1, Yvonne O’Brien1, Peter

ockery2, John Morrison1

1National University of Ireland Galway, Obstetrics & Gynaecology, Galway,reland, 2National University of Ireland Galway, Anatomy, Galway, Ireland

OBJECTIVE: Knowledge of the stereology of human myometrium inregnancy, and its potential link to functional contractility, is limited.he aim of this study was primarily to investigate the stereology ofuman myometrium in the third trimester, and secondarily to evalu-te for a potential influence of maternal body mass index, age andarity.

STUDY DESIGN: Biopsies of human myometrium were obtained from7 women at cesarean section (n�26, n�13, n�18 normal, over-

weight and obese BMI respectively) in the third trimester. These wereparaffin embedded and stained with Masson’s Trichrome stain. Vol-ume fractions of smooth muscle and extracellular matrix were as-sessed using stereological point counting techniques (Figure 1), andconverted to percentage of total tissue. Data were compared usingMann Whitney, ANOVA and Krruskal-Wallis tests.RESULTS: The median gestation was 39 weeks (range 38-40) and the

ean age was 33.8 years (range 18-45) (n�57). For the 3 BMI groupshe parity details (median, range) prior to the index delivery were asollows: normal 1, 0-2, n�26; overweight 1, 0-2, n�13; obese 2, 0-4,�18. Smooth muscle constituted 65.2% �8.9% (SD) and the extra-ellular matrix 32.6% �7.7% (SD) (n�57). There was no correlation

of smooth muscle volume fraction or extracellular matrix volumefraction with maternal body mass index (P� 0.65, 0.24 respectively),age (P� 0.17, 0.26), or parity (P� 0.42, 0.66).CONCLUSION: This study provides reliable data for the relative propor-tions of smooth muscle and extracellular matrix in human myome-trium in the third trimester. The possibility that uterine contractileactivity may be altered in association with advanced maternal age, orincreasing body mass index, is not apparently related to the availabil-ity of smooth muscle. In addition, parity had no effect on the stereo-logical parameters. These findings raise the possibility that metabolicmodulatory factors, rather than the smooth muscle volume, play animportant role in regulation of labor.

Time to change one centimeter in minutes; median (5th and 95th percen-tile); P values obtained from regression models.

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309 The association between dystocicabors and circadian signals

Eva Wiberg-Itzel1, Andrea Pembe2, Anna-carin Wihlbäck3,lisabet Darj4, Helena Åkerud4

1Section of Obstetrics and Gynaecology, Karolinska Institute, Soder Hospital,weden, Department of Clinical Science and Education, Stockholm, Sweden,

2Muhimbili University of Health and Allied Sciences, Dar es Salaam,anzania, Department of Obstetrics and Gynaecology, School of Medicine,ar es Salaam, United Republic of Tanzania, 3University Hospital of Umea,

Sweden, Department of Clinical Science, Obstetrics and Gynecology, Umeå,Sweden, 4Uppsala University, Uppsala, Sweden, 4Department of Women’sand Children’s Health, Uppsala, SwedenOBJECTIVE: Human deliveries commonly occur during the dark pe-iod of the day. Melatonin hormone is released as a circadian signalrom the human brain, and has been shown to have a synergistic effectogether with oxytocin in facilitating the uterine contractions duringabor. Melatonin is inhibited by light and energized by dark. Duringinter the numbers of light hours per day in Sweden are few, buturing the summer they are numerous. In Tanzania there is no seasonifference.

STUDY DESIGN: In 2011,452 Tanzanian and 919 Swedish healthy pri-miparas with a normal pregnancy and a spontaneous onset of laborwere included in the study. Time and date together with the length andoutcome of delivery were studied, and a statistical comparison wasmade.RESULTS: 47% of the Swedish deliveries started in early morning, and

8% ended at midnight. The median time of active labor was signifi-antly longer during the summer season (May to August vs. Novem-er to February, p�0.05). The frequency of labor dystocia was in-reased during summer season, and significantly more in the regionn Sweden with midnight sun (29 vs. 40%, p�0.03). 48% of Tanzania

abors started at midnight, and 41% ended at lunch time. Amonganzanian women, no difference in median time of active delivery

p�0.5) or the frequency of dystocic labors was shown, according toeason of the year (13.7 vs. 14.1 %, p�0.8). Oxytocin was used in 68%f the Swedish deliveries, and the use was higher during the summereason. Oxytocin was used in 31% of the Tanzanian deliveries. Noifference in use of oxytocin was shown according to season.

CONCLUSION: In this project a variation of labor dystocia according toseason of the year has been studied. A significant overrepresentation

Myometrial stereological point counting

of prolonged and dystocic deliveries were shown during the summer

ent to JANUARY 2013 American Journal of Obstetrics & Gynecology S139

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season in Sweden. This new knowledge may be of a great importance,when handling a dysfunctional labor.

310 Association between a polymorphism in anutophagy-related gene, ATG16L1, and time toelivery in women who require induction of labor

Georgios Doulaveris1, Theofano Orfanelli1, Kiesha Benn2,oannis Zervoudakis1, Daniel Skupski2, Steven Witkin1

1Weill Cornell Medical College, Obstetrics and Gynecology, New York, NY,2New York Hospital Queens Medical Center, Obstetrics and Gynecology,

ew York, NYOBJECTIVE: Autophagy is an intracellular process designed to elimi-

ate damaged organelles and proteins and to maintain homeostasis. Aingle nucleotide polymorphism (SNP) in the autophagy-related 16-ike 1 (ATG16L1) gene has been associated with decreased autophagyn humans. Inhibition of autophagy in pregnant mice has been showno result in labor induction. We evaluated whether the ATG16L1 poly-

orphism influenced the time to delivery in pregnant women whoequired labor induction.

STUDY DESIGN: DNA was obtained from 69 women who required la-or induction at term for an unfavorable cervix (Bishop score � 6)nd tested for a SNP in ATG16L1 (rs2241880) by gene amplificationnd endonuclease digestion. Labor induction was by one of threeomparable protocols showing no significant difference in time toelivery between the groups. Indications for induction were post-erm (�294 days) (26), oligohydramnios (17), hypertension or pre-clampsia (10), abnormal fetal heart rate (8), diabetes (3) or othereasons (5).

RESULTS: The ATG16L1 genotype distribution was 44.9% AA, 37.7%G and 17.4% GG and was in Hardy-Weinberg equilibrium. Theean hours (SD) from labor induction to delivery was 20.8 (9.7) foromen who were AA, 19.2 (8.8) for those who were AG and 14.3 (6.6)

or women who were GG (p � 0.03 AA vs. GG, p � 0.04 AA/AG vs.G). The GG prevalence was 24.4% for those who delivered �24ours vs. 4.2% for women delivering �24 hours (p�0.04). The GGenotype was associated with reduced time to delivery for each indi-ation and there was no difference in genotype distribution by indi-ation for labor induction.

CONCLUSION: In women who require labor induction, a decreased ge-netic capacity for autophagy is associated with a more rapid progres-sion to delivery. Inhibition of autophagy may be beneficial in womenwhose labor has to be induced.

311 The third stage of labor–a look into thehysiology of a deserted stage of labor

Hadar Rosen2, Eran Hadar1, Nir Melamed1, Amir Aviram1,ded Raban1, Liat Saltzer1, Ilan Calderon3,al Ben-David3, Avi Ben-Haroush1, Yariv Yogev1

1Rabin Medical Center, Obstetrics and Gynecology, Petach Tiqva, Israel,2Shaare Zedek Medical Center, Obstetrics and Gynecology, Jerusalem, Israel,3Bnai Zion Medical Center, Obstetrics and Gynecology, Haifa, IsraelOBJECTIVE: We aimed to evaluate uterine activity during the 3rd stage

f labor and to compare it to that observed in the 2nd stage of laborsing a novel technique that records electrical uterine myographyEUM).

STUDY DESIGN: Uterine electric activity was prospectively measuredusing EUM in 44 women with singleton pregnancies at term duringthe last 30 minutes of the 2nd stage and throughout the 3rd stage oflabor. The EUM device measures myometrial electrical activity usinga multichannel amplifier and a noninvasive position sensor. A scoringindex (1-5) of uterine electrical activity was developed based on thefollowing parameters: period between contractions (seconds); powerof contraction peaks (root mean square (RMS)) and movement of thecenter of electrical activity (mm). Oxytocin was not administered dur-ing the 3rd stage. Patients were stratified into 2 groups based on the

duration of the 3rd stage (�15 min. and � �15 min.

S140 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2

RESULTS: 1) The mean duration of the 2nd and 3rd stages were1.9�63.5 and 15.4�7.5 minutes, respectively. 2) Significant uterinectivity was identified during the 3rd stage with the power of contrac-ion peaks (Mean RMS) being similar to that observed during the 2ndtage of labor (3.4�0.6 vs. 3.4�0.6 p�0.8). 3) No correlation wasound between the duration of the 3rd stage and EUM measurementsuring the 3rd (p�0.9) or the 2nd (p�0.2) stages of labor. 4) Nossociation was found between EUM during the 3rd stage and parity,aternal age, fetal weight and duration of labor 5) Maternal age, ges-

ational age, gravity, parity, BMI, birthweight, EUM during the 2nd orrd stage, oxytocin use during the 2nd stage, did not differ amonghose who had short vs. long duration of the 3rd stage.

CONCLUSION: EUM allows the unprecedented quantification of 3rdstage contraction intensity. Uterine activity during the 3rd stage iscomparable and as intense to that occurring during the 2nd stage. 3rdstage length cannot be predicted by contraction intensity during the2nd or 3rd stage of labor.

312 Amniotomy: does artificial rupturing of membranes inhe active phase enhance myometrial electrical activity? Aommon practice still in controversy

Hadar Rosen2, Liran Hiersh1, Liat Saltzer1, Amir Aviram1,vi Ben-Haroush1, Nir Melamed1, Oded Raban1,

lan Calderon3, Eran Hadar1, Yariv Yogev1

1Rabin Medical Center, Obstetrics and Gynecology, Petach Tiqva, Israel,2Shaare Zedek Medical Center, Obstetrics and Gynecology, Jerusalem, Israel,3Bnei Zion Medical Center, Obstetrics and Gynecology, Haifa, IsraelOBJECTIVE: Controversy exists if amniotomy by itself is associated

ith shortening of spontaneous labor. Moreover, IUP cannot be mea-ured prior to membrane rupture and tocodynamometry yields lim-ted information regarding contraction intensity. Thus, we aimed tossess uterine myometrial activity before and after amniotomy using aovel technique of Electrical Uterine Myography (EUM).

STUDY DESIGN: EUM was prospectively measured in 23 women withsingleton pregnancy at term in active phase of labor (cervical dilata-tion of 4-8 cm). EUM was continuously measured at least 30 minutesprior and for at least 30 minutes after performing amniotomy. EUMwas measured using non-invasive 9 channels recorder with an EMGamplifier and 3-dimensional position sensor. A scoring index (1-5) ofuterine electrical activity was developed based on the following pa-rameters: period between contractions (seconds); power of contrac-tion peaks (root mean square (RMS) and movement of the center ofelectrical activity (mm).RESULTS: 1) The average power of contractions following amniotomy

as significantly enhanced compared to that before (mean EUM mea-urements 3.21�0.43 vs. 3.44�0.45, p�0.01). 2) In a multivariantogistic regression model accounting for maternal age, gravity, gesta-ional age, BMI, cervical dilatation during amniotomy and use of oxy-ocin in labor, a trend implies that as BMI increases the uterine re-ponse to amniotomy decreases.

CONCLUSION: Data suggests that amniotomy during labor enhanceselectrical uterine activity thus reinforcing the claim that amniotomyaugments labor. A rise in BMI may be a factor hindering this effect.

313 Factors associated with higher oxytocin requirementsHeather Frey1, Methodius Tuuli1, Kimberly Roehl1, Anthony

dibo1, George Macones1, Alison Cahill11Washington University in St. Louis, Obstetrics and Gynecology,

t. Louis, MOOBJECTIVE: Obstetricians frequently encounter women who require

igher doses of oxytocin for labor induction or augmentation than aresually administered, however research regarding this population is

imited. We sought to identify maternal, fetal and labor characteristicsssociated with high maximum oxytocin (max OT) doses required tochieve a spontaneous vaginal delivery.

STUDY DESIGN: A nested case-control study was performed within a

cohort of all consecutive women admitted at term to a single center

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