DTIC ADA546020: The Distribution and Predictive Value of Bishop Scores in Nulliparas between 37 and 42 Weeks Gestation

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TheJournalofMaternal-FetalandNeonatalMedicine,2011;EarlyOnline,1 5
(cid:2)2011InformaUK,Ltd.
ISSN1476-7058print/ISSN1476-4954online
DOI:10.3109/14767058.2011.573831
The distribution and predictive value of Bishop scores in nulliparas between
37 and 42 weeks gestation
PETER E. NIELSEN, BOBBY C. HOWARD, TAMI CRABTREE, ALISON L. BATIG, &
JASON A. PATES
1
1
7/ Madigan HealthSystem, Tacoma, Washington, USA
2
6/
0
n
o Abstract
nter Objective. Thenaturaldistribution andpredictiveaccuracyofBishopscoreswasevaluatedtopredictcesareandelivery(CD)in
Ce nulliparas between37and 42weeks gestation.
al Studydesign. Subjectsunderwentserialdigitalcervicalexaminations.TheBishopscorewasevaluatedasabinaryandcontinuous
c
di factortopredictCDateachgestationalweekbeginningat37weeks.Bishopscoreswerecategorizedas(cid:2)5or45,andCDrates
e
M were compared across Bishop score categories using chi square or Fisher exact tests at each gestational week beginning at
my 37weeks.
Ar Results. Inall,171patientswereprospectivelyfollowed.TheoverallCDratewas27.5%.TheprevalenceofunfavorableBishop
an scores,categorizedas(cid:2)5,decreasedwithincreasinggestationageuntil41weeks.CDratesforthecohortwithunfavorableBishop
g
di scores was higher than those with favorable scores at each week. The likelihood ratio for CD was 1.35 2.00, depending on
a
M gestationalage.TheBishopscorethatbestpredictedsubsequentvaginaldeliveryfollowingexpectantmanagementwas43at37
y weeks and 45 at 39weeks.
b
e.com only. Cscoonrcelu4sio5n.impAlyBinisghoanpsinctorriens(cid:2)ic5alblyethwigeehner3C7Danrdis3k9dwesepeiktsegeexsptaetcitoanntpmredanicatgseamheinght.erCDratecomparedtopatientswithaBishop
mahealthcarersonal use Keywords: Cesarean,Bishop score,distribution
m inforFor p Introduction managed is the appropriate control group rate and avoids
o selection bias associated with comparing electively induced
d fr Bishop scores have been used to predict the success of labor patients with thosewho presentinspontaneous labor.
e
ad induction at term [1]. In addition, vaginal delivery rates The purpose of this investigation was to evaluate the
o
nl followinginductionaresimilartospontaneouslaborwhenthe distributionofBishopscores,theCDratebasedonexpectant
w
o preinduction Bishop score exceeds 8 in nulliparas [2]. management by Bishop score and gestational age, and the
D
d Retrospectivestudiesevaluatinglaborinductiononnulliparas ability to predict CD in nulliparas between 37 and 42 weeks
e
M
with an unfavorable cervix (Bishop score of 8 or less) gestation.
al
at demonstrate a two fold higher cesarean delivery (CD) rate
n
o in those who are induced. [3 9]. However, prospective
Ne Materials and methods
al randomizedtrialsevaluatinginductionoflaborsuggesteither
et no increased risk [10 13] or a lower risk of CD [14]. This was an Institutional Review Board (IRB) approved
F
n Unfortunately, the observational studies compared induction prospective observational study. Potential study participants
er
at with spontaneous labor instead of expectant management. were identified between 34 and 37 weeks gestation. Study
M
J Theonlyoptionforprovidersorpatientsiseitherinductionor enrollment began in May 2005 and continued through the
expectant management, not spontaneous labor, since neither proscribed cutoff of March 2007. Individuals who met the
thepatient northeprovider can ensure thisoutcome [15]. followinginclusioncriteriawereofferedenrollment:noknown
Evaluation of potential factors for predicting successful indication for scheduled delivery, nulliparous, singleton gesta
vaginal delivery at term is important since maternal fetal tion,cephalicpresentation,age 18 to40years,no known fetal
complications increase at gestational ages beyond 38 weeks anomaly,nocontraindicationtolabororvaginaldelivery,intact
[16].Inaddition,characterizingBishopscoresandexpectant amniotic membranes, reliable for follow up. After informed
management delivery outcomes in term nulliparous patients consent, enrolled subjects were examined at each subsequent
may guide management options. Finally, these data could routineclinicvisitbeginningnotearlierthan37weeksgestation.
helpdesignastudyevaluatingtheeffectofelectiveinduction A standardized Bishop scoring data sheet was used and com
in nulliparas, since the rate of CD in patients expectantly pleted immediately following the examination. Examinations
(Received21October2010;revised16March2011;accepted17March2011)
Correspondence: Peter E. Nielsen, Department of Obstetrics and Gynecology, Madigan Army Medical Center, MCHJ-OG (ATTN: COL Nielsen),
Tacoma,WA98431,USA.Tel:þ253-968-5161.Fax:þ253-968-5508.E-mail:[email protected]
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1. REPORT DATE 3. DATES COVERED
2011 2. REPORT TYPE 00-00-2011 to 00-00-2011
4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER
The Distribution And Predictive Value Of Bishop Scores In Nulliparas
5b. GRANT NUMBER
Between 37 And 42 Weeks Gestation
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
Madigan Army Medical Center, MCHJ-OG (ATTN: COL REPORT NUMBER
Nielsen,Department of Obstetrics and Gynecology,Tacoma,WA,98431
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)
11. SPONSOR/MONITOR’S REPORT
NUMBER(S)
12. DISTRIBUTION/AVAILABILITY STATEMENT
Approved for public release; distribution unlimited
13. SUPPLEMENTARY NOTES
Journal of Maternal-Fetal and Neonatal Medicine,Early Online, pgs 1-5, 2011
14. ABSTRACT
Objective. The natural distribution and predictive accuracy of Bishop scores was evaluated to predict
cesarean delivery (CD) in nulliparas between 37 and 42 weeks gestation. Study design. Subjects underwent
serial digital cervical examinations. The Bishop score was evaluated as a binary and continuous factor to
predict CD at each gestational week beginning at 37 weeks. Bishop scores were categorized as 5 or 45, and
CD rates were compared across Bishop score categories using chi-square or Fisher exact tests at each
gestational week beginning at 37 weeks. Results. In all, 171 patients were prospectively followed. The
overall CD rate was 27.5%. The prevalence of unfavorable Bishop scores, categorized as 5, decreased with
increasing gestation age until 41 weeks. CD rates for the cohort with unfavorable Bishop scores was higher
than those with favorable scores at each week. The likelihood ratio for CD was 1.35?2.00, depending on
gestational age. The Bishop score that best predicted subsequent vaginal delivery following expectant
management was 43 at 37 weeks and 45 at 39 weeks. Conclusion. A Bishop score 5 between 37 and 39
weeks gestation predicts a higher CD rate compared to patients with a Bishop score 45 implying an
intrinsically higher CD risk despite expectant management.
15. SUBJECT TERMS
16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a. NAME OF
ABSTRACT OF PAGES RESPONSIBLE PERSON
a. REPORT b. ABSTRACT c. THIS PAGE Same as 6
unclassified unclassified unclassified Report (SAR)
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std Z39-18
2 P. E. Nielsen et al.
wererepeatedateachvisituntildelivery.TheBishopscorewas
calculated at each examination using the cervical dilation,
effacement,consistency,position,andstation[1].Thecervical
assessments were performed by the particular staff or resident
obstetricianconductingtheofficevisitwiththepatientandthe
previous Bishop score was not available to this examiner.
Delivery data were collected for each participant and categor
izedaseitheravaginalorCD.Deliveriesthatoccurredvaginally
with use of forceps or vacuum assistance were categorized as
vaginal deliveries. Expectant management was defined as
weekly routine obstetric visits and delivery planned only for
thedevelopmentofmaternalorfetalindicationsorby42weeks
gestation.
Using a logistic regression to determine the odds ratio
1 (OR), the Bishop score was evaluated as both a binary and a
1
7/ continuous factor to predict CD at each gestational week
2
6/ beginning at 37 weeks. For the binary evaluation, Bishop
0
on scores were categorized as (cid:2)5 or 45 as this Bishop score
er cutoff was previously studied in our institution and found to
nt
e be clinically useful in distinguishing a favorable from an
C
al unfavorablecervix[13].Usingthisbinarycategorization,CD
c
di rateswerecomparedacrossBishopscorecategoriesusingthe
e
M
chi square and Fisher exact test at each gestational week
y
m beginning at 37 weeks. The Bishop score at a given
Ar Figure1.Studyenrollment.
n observational window was used to evaluate subsequent CD
ga atanytimefollowingthiswindow.Thesensitivity,specificity,
di
a positiveandnegativelikelihoodratios,andpositivepredictive 19% were for pregnancy induced hypertension, 7% for
M
y value (PPV) and negative predictive value (NPV) of the premature rupture of membranes, and the remaining 5% (1
b
e.com only. Bistisicho(RpOscCo)recuwravsedweatesramlsionecdre.aAterdectoeivfuerrthoepreeravtaoluractheaBraischteorp pnaotnierenatsesaucrhin)gfofretuanlrhemeairtttintrgacbiancgk.pTaihne,oolivgeorhalyldCraDmnriaotse,awnads
mahealthcarersonal use svt0hca.5oalutr(eetishn.aedTsiachpraeetriaepndugvicnaatldouueresrseotlwhfeeseCsrReDpOcreaCadlcciucrcotluaosrtrsev)de.mFtwuooalrttseiapsleltllestshhpyetpohnotaeuntnhllteoihsaryilsepqctoeuutshtatelso,stifoasf 2isTnp7hdo.e5un%ctCatinDo(e4no7rua/o1tsef7l1aalb)ta.obeTroacrwhheacsgCoe4mDs2tp.a4rata%iroteend(ao2lf5two/t5he9oteh)skeovwseperaasstuwie2shn51ot.9s0.%w6p%rhe(o2s(e/r28ne2)tq/e1uad1tir23ei)dn7.
m inforFor p pcavnatl.uAe opfriloersisstahmanple0.s0i5zewcaaslccuolantsioidnerfeodr tshtaistissttiucdalylywsaigsnnifiot w19e.e6k%,2(59./94%6)(a7t/2470) awte3e8ksw,eaenkds,3381.5.1%%((1109//2661))aatt4319wweeeekkss,.
o
d fr performedastheactualincidenceofBishopscoresanddegree Onlyonepatientinthestudydeliveredat42weeksgestation
e of change across a range of gestational ages was unknown at and this delivery occurred vaginally. All patients included in
d
a
o thetime ofprotocol preparation. thisevaluationdeliveredbetween37and42gestationalweeks,
nl
w with the highest percentage (36.1%) delivering at 39 weeks.
o
D Ninety onepercentofpatientshadanultrasoundexamination
d Results
Me performedat(cid:2)20weeksgestationand52%hadanultrasound
al Three hundred and seventeen patients were identified for examination performed at less than 13 weeks gestation
nat possible enrollment between 34 and 37 weeks gestation. Of confirming gestational age. Last menstrual period dating
o
Ne these, 233 rendered their consent for participation and 84 and an ultrasound examination performed at greater than
al declined enrollment. Following enrollment, 62 additional 20 weeks gestation were used to assess gestational age in the
et
F patients were excluded. Reasons for exclusion included remaining 9% ofpatients.
n
er withdrawalofconsent,failuretopresentforfollow upbeyond ROC curves evaluating the relationship between Bishop
at
M 37 weeks, and delivery prior to 37 weeks. Subjects were also scoresbygestationalageandsubsequentCDwerecreatedfor
J withdrawnfromtheevaluation iftheydidnotmeetinclusion each gestational week from 37 to 40. The ROC curves at 37
criterionfollowingenrollmentbutbefore37gestationalweeks and39weeksdemonstratedthelargestareaunderthecurveat
(i.e., developed an indication for induction or primary CD 0.77 and 0.73, respectively (Figures 2and 3), and both were
after enrollment but before 37 weeks gestation). There were statistically significant (p50.0001). The Bishop score that
171 evaluable patients who delivered after 37 gestational bestpredictedsubsequentvaginaldeliveryfollowingexpectant
weeks and for whom cervical examination and delivery data management was 43 at 37 weeks and 45 at 39 weeks. The
were available at thecompletion ofthestudy (Figure 1). sensitivityofaBishopscoreof3at37weekswas80%andfor
Themeanmaternalagewas23.6years(SD¼4.1)andthe a Bishop scoreof5 at 39weeks was 73%.
mean gestational age at enrollment was 37.6 weeks (SD¼ The prevalence of unfavorable Bishop scores, defined as
0.6).EightypatientshadtheirfirstBishopscoreassessmentat thosescores(cid:2)5,decreasedwithincreasinggestationageuntil
37 weeks gestation and 91 had their first Bishop score 41gestational weeks. At37gestational weeks,71.3%[57/80,
assessmentat38weeksgestation.Thirty fivepercent(59/171) 95% confidence interval (CI): 60.5 80.0] of enrollees had a
ofpatientsrequiredinductionoflaborafterenrollmentdueto Bishopscore(cid:2)5.Theratewas63.7%(79/12495%CI:55.0
thedevelopmentofamaternalorfetalindication.Specifically, 71.6) at 38 gestational weeks, 46.6% (48/103, 95% CI:
69%ofinductionswereforpostdatism(41weeksorgreater), 37.3 56.2) at 39 gestational weeks, 40.4% (23/57, 95% CI:
Predictive value of nulliparous Bishop score 3
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adi Figure2.ROCcurveforCDbasedonBishopscoreat37weeksgestation(n 80).PointsonthecurvearevaluesofBishopscore.Approximate
M
y areaunderthecurve 0.771(standarderror 0.056).
b
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Figure3.ROCcurveforCDbasedonBishopscoreat39weeksgestation(n 102).PointsonthecurvearevaluesofBishopscore.Approximate
areaunderthecurve 0.731(standarderror 0.056).
28.6 53.3) at 40 gestational weeks, and 44.0% (11/25, 95% The CD rate was statistically significantly increased by more
CI: 26.7 62.9) at 41gestational weeks. thantwo fold at37,38,and 39gestational weeks (Figure4).
CD ratesforthecohortwithBishopscores (cid:2)5washigher As abinaryfactortopredict CD,aBishop score(cid:2)5at 37
thanforthecohortwithBishopscores45ateachgestational gestationalweekshadanORof6.6.ThisORdecreasedwith
week,basedonthegestationalageatBishopscoreevaluation. advancinggestationalage(TableI).Asacontinuousfactorto
4 P. E. Nielsen et al.
predictCD,eachunitincreaseintheBishopscoredecreased on gestational age. Specifically, the probability ofsubsequent
theriskofCD.TheeffectofincreasedBishopscorevariedby CDwithaBishopscoreof(cid:2)5at39weeksis44%comparedto
gestationalweek,withthelowestOR(thehighestincremental 15% (p50.05). This implies an intrinsically higher CD risk
reduction in CD rate with each unit increase in the Bishop in patients with unfavorable Bishop scores at this gestational
score) occurring at 37gestational weeks (Table II). age, despite expectant management, and may explain why
Thesensitivity,specificity,positiveandnegativelikelihood previouslypublishedobservationalstudiesdemonstrateatwo
ratios, and PPVs and NPVs for the Bishop score (cid:2)5 as a fold increased risk of CD in patients induced with an
predictor of CD was calculated by gestational week unfavorable cervix [3 9]. These studies compared patients
(Table III). inducedwithanunfavorablecervixtothosewhopresentedin
spontaneouslaborandthuswithafavorablecervix.Ourdata
confirm that patients who are admitted in spontaneous labor
Discussion
haveapproximatelyone halftheCDrateofthosewhorequire
ThepercentageofnulliparaswithaBishopscore(cid:2)5decreases inductionoflaborforamaternalorfetalindication.However,
after 37 gestational weeks. A Bishop score (cid:2)5 at any if elective induction were instead compared to expectant
1 gestational age beyond 37 weeks predicts a higher CD rate management (whose probability of CD is greater than two
1
7/ comparedtopatients withaBishop score45 andtheOR of foldhigheramongthosewithanunfavorablecervixcompared
2
6/ eventual CD is highest (OR¼6.6) when the Bishop score is tothosewithafavorablecervix)thetwogroupsmayshowno
0
on (cid:2)5 at 37 gestational weeks. At this gestational age, each unit difference in CD rates since in our study, 35% of patients
er increase in the Bishop score has the greatest impact on expectantlymanagedultimatelyrequiredaninductionoflabor
nt
e reducing therisk ofCD (OR0.60). resulting ina42% CD ratein thisgroup.
C
al PatientswithBishopscores(cid:2)5hadCDratesthatwere2to Itisalsopossiblethatbycontinuingexpectantmanagement
c
di 4timesgreaterthanthosewithBishopscores45,depending beyond39weeksgestation,thelikelihoodofCDmayactually
e
M
increaseoverthosepatientselectivelyinducedsincenumerous
y
m factors which may increase the risk of CD also increase with
Ar
n advancing gestational age such as birth weight, placental
ga insufficiency, oligohydramnios, and preeclampsia.
di
a The strengths of our study include the prospective design
M
y andthefollow upandevaluationofonlythosepatientsatterm
b
e.com only. tgheasttahtaiodnn.oAplllpanatfioenrtasnwinerdeiceaxtpeedcitnadnutlcytmioannoafgleadb,omraeta3n7inwgetehkast
mahealthcarersonal use rdiinnoedduliiutvcicenatrteiyioonponlbsoasfntolenartebrdiobcryoicns4alny2roeftowwpreeaterhskfeosprdmrgeoevevseditdlaoietnipdoomnuw.erniIittnhnsotfwaitdmeudetaikitotleiynor;nnvta,hilseeiotrlsreecffoateinrtveade,l
m inforFor p tuhnisdestruwdeynitsnaontcinondfuocutinodnedobfyltahbisormafonragcelmineincat.lPiantdieincatstioonnlsy.
o
d fr Adequate numbers of patients also permitted stratification of
e deliveryoutcomebasedonBishopscoreandgestationalageat
d
a
o examination. Finally, confirmation of gestational age by an
nl
w ultrasound examination at less than 20 weeks gestation was
o
D Figure4.CDrateforenrolleeswithBishopscores(cid:2)5comparedto performedongreaterthan90%ofpatients.
Med thosewithBishopscores45bygestationalageatassessmentofscore. The limitations ofthis study include thefact that multiple
al Samplesizebygestationalage:37weeks,N 80;38weeks,N 124; examiners were used to document the Bishop score and
nat 39weeks,N 103;40weeks,N 57;41weeks,N 25(*p50.05, interobserver variation in examinations was not performed.
o **p 0.05).
Ne However,allproviderswereexperiencedupper levelresidents
al or attending physicians and a standardized Bishop scoring
et
F TableI.UsingBishopscore(cid:2)5asabinarypredictorforCD. sheet was used and completed immediately following the
n
er examination.Proscribedclinicalindicationsforinductionand
at Gestationalage(weeks) OR 95%CI
M labor management for each patient studied were not
J 37(n 80) 6.60 1.41 31.0 specifically delineated for this study and were left up to the
38(n 124) 2.66 1.05 6.77 discretion of the attending physician. However, our large
39(n 102) 4.56 1.78 11.72
40(n 57) 4.00 1.04 15.44
41(n 25) 3.00 0.57 15.77
TableIII.Sensitivity,specificity,positive(LRþ)andnegative(LR )
likelihood ratios, and PPV and NPV for Bishop score (cid:2)5 as a
predictorofCDinexpectantlymanagednulliparous.
TableII.UsingBishopscoreasacontinuousfactortopredictCD.
Gestationalage
Gestationalage(weeks) OR 95%CI (weeks) Sensitivity Specificity LRþ LR PPV NPV
37(n 80) 0.59 0.44 0.88 37(n 80) 91.7 37.5 1.47 0.22 38.6 91.3
38(n 124) 0.85 0.72 1.01 38(n 124) 78.8 41.8 1.35 0.51 32.9 84.4
39(n 102) 0.72 0.59 0.87 39(n 102) 72.4 63.5 1.98 0.43 43.8 85.5
40(n 57) 0.79 0.61 1.03 40(n 57) 66.7 66.7 2.00 0.50 34.8 88.2
41(n 25) 0.86 0.62 1.19 41(n 25) 60.0 66.7 1.80 0.60 54.6 71.4
Predictive value of nulliparous Bishop score 5
group practice has no ‘private patients’ and all clinical
References
decisionsaremadebasedonagenerallystandardizedpractice
patternwithresidentsmanagingpatientssupervisedbyanin 1. Freidman EA, Niswander KR, BayonetRivera NP, Sachtleben
houseattendingobstetrician.Thisfactminimizesvariationin MR. Relationship of prelabor evaluation in inducibility and the
courseoflabor.ObstetGynecol1966;28:495 501.
our clinical practice for both antepartum and intrapartum
2. AmericanCollegeofObstetriciansandGynecologists:induction
patients. Another limitation of this study may be that the
of labor, ACOG Practice Bulletin No. 10. Washington, DC:
incidenceofCDisrelatedtootherfactorsbesidesthecervical
AmericanCollegeofObstetriciansandGynecologists;1999.
Bishop score to include body mass index or the presence of
3. Yeast JD, Jones A, Poskin M. Induction of labor and the
gestational diabetes and other medical conditions. However, relationship to cesarean delivery: a review of 7001 consecutive
toourknowledgethestrongestpredictorofvaginalbirthisthe inductions.AmJObstetGynecol1999;180:628 633.
cervical condition prior to induction or at presentation in 4. Maslow AS, Sweeny AL. Elective induction of labor as a risk
labor,andothermaternalorfetalcomorbiditiesarenotclearly factor for cesarean delivery among lowrisk women at term.
establishedmodifiersofcervicalripeness[17]. Itwouldhave ObstetGynecol2000;95:917 922.
beenoptimaltoknowwhichwomenprogressedtoactivelabor 5. Seyb ST, Berka RJ, Socol ML, Dooley SL. Risk of cesarean
delivery with elective induction of labor at term in nulliparous
1 (4cm)butweunfortunatelydidnotcollectthisdata.Finally,
7/1 womenwereenrolledpriorto37weeksgestation(between34 women.ObstetGynecol1999;94:600 607.
6/2 and37weeksgestation) toprovidecervicalexamination data 6. PrysakM,CastronovaFC.Electiveinductionversusspontaneous
0 labor: a casecontrol analysis of safety and efficacy. Obstet
on forthestudybythisgestationalage.Failuretopresentforcare Gynecol1998;92:47 52.
nter beyond 37 weeks or preterm birth were the most common 7. Macer JA, Macer CL, Chan LS. Elective induction versus
Ce reasons forexclusion. spontaneous labor: a retrospective study of complications and
al Thisstudyprovidesimportantdataforfurtherevaluationof outcome.AmJObstetGynecol1992;166:1690 1697.
c
di theeffectofelectiveinductionoflaborcomparedtoexpectant 8. JohnsonDP,DavisNR,BrownAJ.Riskofcesareandeliveryafter
e
M management at term. A recent review of this subject and the induction at term in nulliparous women with an unfavorable
y
m accompanying clinical commentary highlighted the need for cervix.AmJObstetGynecol2003;188:1565 1572.
Ar 9. VahratianA,ZhangJ,TroendleJF,SciscioneAC,HoffmanMK.
gan cbueyrroenndt 3st9udwieeeskesvgaelustaattiinogneslienccteivetheinreduacrteionnoorefcleanbtorreaptorotsr Labor progression and risk of cesarean delivery in electively
di inducednulliparas.ObstetGynecol2005;105:698 704.
a that adequately define the effects of elective induction of
M 10. Tylleskar J, Finnstrom O, Leijon I, Hedenskog S, Ryden G.
by nulliparous patients [15,18]. In fact, well designed rando Spontaneous labor and elective induction a prospective
e.com only. mexipzeecdtacnltinmicaalnatgrieamlsenotf aetle3ct9iveweienkdsucatniodnboefyolnabdorthavtersaures rGaynndeocmolizSecdanstdud1y9.79I.;5E8f:f5e1c3ts5o1n8.mother and fetus. Acta Obstet
mahealthcarersonal use apreedfafqreeiuqcteytussatatoenoflfdyetlpehBcoisitwsivheeeodrepiitdnodsrticuaooclrtae[ios1sn8ae]ts.osfrUialmnnabdtpioolormrftuaairztntahtoteirsorunbdbegaywtroaoanuscdplaas3r9issfiupewceshecetifihkacess 1112.. CAlEalmboeolceartni:RvoaeAKri,na,nHdSduoaociwttmoiioeiKnseP,odWSfphl,aroMbodosaparceTaNct,tia3Tvu9eagnwthirteiAoaenlk,.sYLMooafCsnhgc.ieehEstatlar1eatc9iotH7inv5,:e;N1ai:n7ipcd6rhou7isjciptm7ieo7acn0tM.ivoef.
m inforFor p guensdtaetrioann, itnhsistitcultiinoincaall rmevaineawgebmoeanrdt sahpopurlodveodnlpyrobteocooflfearnedd 13. NrainedlsoemnizPeEd,tHriaolw.JarOdbBstCet,GHyilnlaCecCo,lRLeasrs1o9n99P;L2,5:H33oll3a7n.d RHB,
o Smith PN. Comparison of elective induction of labor with
d fr electiveinductionoflaborpriorto39weeksgestationshould favorable Bishop scores versus expectant management: a
e never be performed or offered if amniotic fluid analysis does
d randomized clinical trial. J Matern Fetal Neonatal Med 2005;
a
nlo notconfirmfetallungmaturitybecauseofincreasedneonatal 18:59 64.
w morbidity. 14. CaugheyAB,SundaramV,KalmalAJ,GiengerA,ChengYW,
o
D McDonaldKM,ShafferBL,OwensDK,BravataDM.Systema
d
Me tic review: elective induction of labor versus expectant manage
Acknowledgment
al mentofpregnancy.AnnInternMed2009;151:252 263.
nat Presentedatthe55thAnnualClinicalMeeting/ACOG,May, 15. CaugheyAB,NicholsonJM,ChengYW,LyellDJ,Washington
Neo 2007. AE.Inductionoflaborandcesareandeliverybygestationalage.
al AmJObstetGynecol2006;195:700 705.
et 16. Caughey AB, Musci TJ. Complications of term pregnancies
F Declaration of interest: The authors report no conflicts of
n beyond37weeksofgestation.ObstetGynecol2004;103:57 62.
ater interest.Theauthorsaloneareresponsibleforthecontentand 17. Crane JM. Factors predictinglabor induction success: a critical
M writingofthepaper,andtheviewsexpresseddonotrepresent analysis.ClinObstetGynecol2006;49(3):573 584.
J officialpoliciesoftheUSFederalGovernmentorDepartment 18. Macones GA. Elective induction of labor: waking the sleeping
ofDefense. Supported byAdeza Biomedical. dogma?AnnInternMed2009;151:281 282.