Elective caesarean section at 38 weeks versus39 weeks: neonatal and maternal outcomes in arandomised controlled trial*J Glavind,a SF Kindberg,a N Uldbjerg,a M Khalil,b AM Møller,c BB Mortensen,d OB Rasmussen,e

JT Christensen,f JS Jørgensen,g TB Henriksenh

a Department of Obstetrics and Gynaecology, Aarhus University Hospital, Aarhus N, Denmark b Department of Obstetrics and Gynaecology,

Kolding Hospital, Kolding, Denmark c Department of Obstetrics and Gynaecology, Aalborg University Hospital, Aalborg, Denmarkd Department of Obstetrics and Gynaecology, Regional Hospital of Viborg, Viborg, Denmark e Department of Obstetrics and Gynaecology,

Regional Hospital of Randers, Randers, Denmark f Department of Obstetrics and Gynaecology, Regional Hospital of Herning, Herning,

Denmark g Department of Obstetrics and Gynaecology, Odense University Hospital, Odense, Denmark h Department of Paediatrics, Aarhus

University Hospital, Aarhus N, Denmark

Correspondence: Dr J Glavind, Department of Obstetrics and Gynaecology, Aarhus University Hospital, Brendstrupgaardsvej 100, DK-8200

Aarhus N, Denmark. Email julie.glavind@dadlnet.dk

Accepted 14 April 2013. Published Online 20 May 2013.

Objectives To investigate whether elective caesarean section before

39 completed weeks of gestation increases the risk of adverse

neonatal or maternal outcomes.

Design Randomised controlled multicentre open-label trial.

Setting Seven Danish tertiary hospitals from March 2009 to June

2011.

Population Women with uncomplicated pregnancies, a single

fetus, and a date of delivery estimated by ultrasound scheduled for

delivery by elective caesarean section.

Methods Perinatal outcomes after elective caesarean section

scheduled at a gestational age of 38 weeks and 3 days versus

39 weeks and 3 days (in both groups �2 days).

Main outcome measures The primary outcome was neonatal

intensive care unit (NICU) admission within 48 hours of birth.

Secondary outcomes were neonatal depression, NICU admission

within 7 days, NICU length of stay, neonatal treatment, and

maternal surgical or postpartum adverse events.

Results Among women scheduled for elective caesarean section at

38+3 weeks 88/635 neonates (13.9%) were admitted to the NICU,

whereas in the 39+3 weeks group 76/637 neonates (11.9%) were

admitted (relative risk [RR] 0.86, 95% confidence interval [95%

CI] 0.65–1.15). Neonatal treatment with continuous oxygen for

more than 1 day (RR 0.31; 95% CI 0.10–0.94) and maternal

bleeding of more than 500 ml (RR 0.79; 95% CI 0.63–0.99) wereless frequent in the 39 weeks group, but these findings were

insignificant after adjustment for multiple comparisons. The risk

of adverse neonatal or maternal outcomes, or a maternal

composite outcome (RR 1.1; 95% CI 0.79–1.53) was similar in the

two intervention groups.

Conclusions This study found no significant reduction in neonatal

admission rate after ECS scheduled at 39 weeks compared with

38 weeks of gestation.

Keywords Elective caesarean section, maternal outcomes, neonatal

intensive care unit admission, neonatal outcomes, timing.

Please cite this paper as: Glavind J, Kindberg S, Uldbjerg N, Khalil M, Møller A, Mortensen B, Rasmussen O, Christensen J, Jørgensen J, Henriksen T.

Elective caesarean section at 38 weeks versus 39 weeks: neonatal and maternal outcomes in a randomised controlled trial. BJOG 2013;120:1123–1132.

Introduction

British and American societies in obstetrics recommend

elective caesarean section to be scheduled after 39 com-

pleted weeks of gestation.1,2 This recommendation is based

on a subset of several observational studies suggesting a

strong association between earlier gestational age at elective

caesarean section delivery and risk of respiratory morbid-

ity.3–7 In addition, two recent, large cohort studies investi-

gated timing of elective caesarean section and the incidence

of a composite adverse neonatal outcome including neona-

tal death or any of a series of adverse events. Both showed

a decreasing incidence of the composite outcome with

increasing gestational age from 37 to 39 completed weeks

of gestation.8,9 In contrast, any maternal benefit of post-

poning elective caesarean section to 39 completed weeks*Trial registration: www.clinicaltrials.gov, number NCT00835003

ª 2013 RCOG 1123

DOI: 10.1111/1471-0528.12278

www.bjog.orgGeneral obstetrics

has not been shown, but knowledge is sparse when it

comes to maternal consequences of elective caesarean sec-

tion timing.10,11

However, confounding by indication may impair results

from observational studies. In this case, neonates with a

higher risk of an adverse outcome may be over-represented

in caesarean sections undertaken before 39 weeks for rea-

sons other than the caesarean section per se. This method-

ological problem would only be solved in a randomised

controlled trial. Furthermore, to fully investigate the neona-

tal and maternal benefits or adverse events associated with

a certain elective caesarean section timing, outcomes from

women with unscheduled procedures who intended to deli-

ver by elective caesarean section should be included in the

assessment.

We therefore conducted a randomised controlled trial of

neonatal and maternal morbidity after elective caesarean

section scheduled at 38+3 weeks compared with 39+3 weeks

of gestation. The primary study objective was to investigate

the risk of neonatal intensive care unit (NICU) admission

associated with elective caesarean delivery scheduled before

versus after 39+0 weeks of gestation.

Methods

We conducted a multicentre, open-label randomised con-

trolled trial in seven Danish hospitals, all with an NICU

within the hospital. Approvals were obtained from The

Central Denmark Region Committees on Biomedical

Research (ID M-20080142) and the Danish Data Protection

Agency (ID 2008-41-2522). Registration at www.Clinical-

trials.gov was ensured with identification number

NCT00835003. An independent trial steering committee

was appointed for data monitoring, safety and advice dur-

ing the trial.

Clinical management and data collectionParticipants were randomly assigned in a 1:1 ratio to an

elective caesarean section scheduled 11 days before the esti-

mated due date (38+3 weeks; referred to as 38-week group)

or to an elective caesarean section scheduled 4 days before

the estimated due date (39+3 weeks; referred to as 39-week

group). In both groups, the scheduled date was allowed to

deviate �2 days from this specific date.

Hospital staff and participants were all aware of the esti-

mated gestational age at the elective caesarean section sched-

uled date. During antenatal consultations, participants and

nonparticipants had a case report form assessing inclusion

and exclusion criteria filled out by the responsible physician,

and after written consent had been obtained, elective caesar-

ean section was booked according to the randomisation. To

limit the influence of subjective timing preferences, the

responsible staff members were asked to book the elective

caesarean section according to a prioritised gestational

age sequence (38+3 > 38+2 > 38+4 > 38+5 > 38+1 versus

39+3 > 39+4 > 39+2 > 39+1 > 39+5).

Neonatal outcomes were assessed 30 days after delivery

or at final discharge (with NICU length of stay >30 days)

by a designated physician, research nurse, or midwife.

Maternal outcomes were assessed 30 days postpartum. Data

from all the participating hospitals were collected and

checked for accuracy by the first author, before they were

entered into a database (EPIDATA software version 3.1).12

Study population and settingSingleton pregnant women with a gestational age deter-

mined by ultrasound before 15 weeks of gestation were eli-

gible for inclusion, when a decision of delivery by elective

caesarean section was made. Exclusion criteria were multi-

ple gestations, age <18 years, language difficulties requiring

an interpreter, or an estimated risk of the caesarean section

being undertaken before 39+5 weeks of gestation. Accord-

ingly, women with conditions such as placenta praevia,

high blood pressure, or elevated levels of liver enzymes

were not included. Women with type 1 diabetes or gesta-

tional diabetes, verified at the time of randomisation by an

oral glucose tolerance test, were also excluded from partici-

pation. Any fetal condition warranting delivery before

39+5 weeks or necessitating NICU admission also excluded

participation in the study.

In Denmark, elective caesarean section is only performed

at public hospitals; hence, women assessed for eligibility in

this study represented the entire population of the partici-

pating councils. All participating hospitals had one neona-

tal department (in our facilities named the neonatal

intensive care unit/NICU) and in-house obstetrician, paedi-

atrician and anaesthesiologists available day and night, with

physicians typically working in 8-, 16- or 24-hour shifts.

The participating units complied with the Danish National

Obstetrics Guidelines for elective caesarean section includ-

ing spinal anaesthesia as the preferred analgesia and admin-

istration of prophylactic intravenous antibiotics during the

procedure. A midwife handled the neonate immediately

after the birth.

Paediatricians were not routinely present in the operat-

ing theatre and were only called in if the neonate presented

with clinical signs warranting paediatric assistance. At all

the participating hospitals, NICU admission and separation

of the mother and child were avoided if possible, and all

decisions related to NICU admission were on a case-to-case

basis. Although the paediatricians responsible for the deci-

sion to admit the neonate to the NICU were not blinded

to gestational age at delivery, only neonates with a gesta-

tional age <35 weeks were routinely admitted to the NICU.

If paediatricians were called to assess the newborn, they

were unaware that a trial was being conducted.

1124 ª 2013 RCOG

Glavind et al.

RandomisationParticipants were randomised using a computer-generated

voice response telephone randomisation system in a per-

muted block design with block sizes of two, four and six in

random order, stratified by previous caesarean and site.

Study outcomesThe primary outcome was admission to the NICU, regard-

less of cause, within 48 hours of birth, which was assessed

by information from individual hospital records. Secondary

short-term neonatal outcomes were admission to the NICU

within 7 days of birth, NICU length of stay, type and dura-

tion of treatment (mechanical ventilation, continuous oxy-

gen supplementation, continuous positive airway pressure

[CPAP], intravenous antibiotics, treated hypoglycaemia),

Apgar score, umbilical artery pH and standard base excess

values. We defined any respiratory morbidity as mechanical

ventilation, continuous oxygen supplementation, or CPAP

during NICU admission. Serious respiratory morbidity was

defined as mechanical ventilation, or three or more initi-

ated days of treatment with oxygen or CPAP during NICU

admission. Furthermore, birthweight and gender were reg-

istered. If a neonate was transferred to another NICU, data

were registered continuously throughout the entire admis-

sions, and the total admission period was registered until

discharge from the final NICU.

The following maternal outcomes were registered: mater-

nal death, hysterectomy, or serious thromboembolic compli-

cations (deep venous thrombosis or pulmonary embolism).

Surgical adverse outcomes such as injury to bowel or bladder

or a uterine lateral tear were registered if they were specifi-

cally mentioned in the procedure description. Likewise, pro-

cedural complications such as adherences, difficulties in

delivery (prolonged, described as difficult, use of forceps or

vacuum), or the presence of total uterine rupture or a noted

dehiscence (intact serosa) were registered if mentioned in the

operation description. Anaesthetic complications included

serious cases of hypotension or hypertension, spinal head-

ache, or the need for general anaesthesia. A re-operation was

registered if any of the following procedures were performed

after delivery: evacuation, wound opened because of sus-

pected infection or bleeding in the abdomen, or other opera-

tions such as the placement of a JJ-catheter. Treatment for

excessive postoperative bleeding was registered if a blood

transfusion was administered, or if uterotonic medication in

addition to prophylactic treatment was instituted at the

operating theatre. Total blood loss volume was defined as the

volume registered in the operating theatre during the caesar-

ean section procedure, or in vaginal deliveries until transfer

from the delivery room occurred. Any antibiotic treatment

and the suspected source of infection (endometritis, wound

infection, mastitis, or any other infection attributed to the

delivery) were registered from the patient record. The diag-

nosis of endometritis was based on clinical criteria with fever,

elevated biochemical inflammatory markers and vaginal dis-

charge. Finally, we constructed a composite outcome with

inclusion of at least one of the following adverse outcomes:

maternal death, hysterectomy, pulmonary embolism or deep

venous thrombosis, uterine incision lateral tear, injury to

bowel or bladder, procedural or anaesthesia complications,

rupture or dehiscence, bleeding requiring treatment, addi-

tional operations, or antibiotic treatment within 30 days of

delivery.

Sample sizeWith an a (two-sided) of 0.05 and a power of 0.80, an

estimated sample size of 1010 participants was calculated

based on primary outcome proportions of 8% (39-week

group) and 14% (38-week group), which were numbers

available from a large cohort (women with diabetes and

fetal malformations excluded) at the beginning of the

trial in 2008.6 After delivery of 750 participants, approxi-

mately 9% of the participants had not been delivered

within the two 5-day randomisation group intervals for

reasons such as the mother’s request for another delivery

date, miscalculations of the gestational age, or postponing

of the procedure for logistic problems in the operating

theatre. To account for the higher than expected non-

compliance, the steering committee recalculated the sam-

ple size, without knowledge of the results until then, and

decided to increase the sample size to a total of 1270

participants.

Statistical analysesBasic demographic data are presented with counts and per-

centages for categorical variables, with mean and standard

deviation for continuous Gaussian variables and with med-

ian and interquartile range (IQR) for continuous non-

Gaussian variables. We analysed all data according to the

intention-to-treat principle.

In the outcome analyses, relative risks and absolute risk

differences with 95% confidence intervals (95% CI) were

calculated for dichotomous outcomes using Fisher’s exact

test. Non-Gaussian continuous variables were compared

using the Wilcoxon rank-sum test, and birthweight was

compared using Student’s t test. For the primary outcome

and the maternal composite outcome a potential centre

effect was evaluated by testing the hypothesis of no treat-

ment by centre interaction in a multiple logistic regression

model. Adjustment for multiple comparisons (Bonferroni)

was made in evaluating the secondary outcomes.

All data analyses were performed using the statistical

software program STATA v.11 (2009).13

ª 2013 RCOG 1125

Timing of elective caesarean section: RCT

Results

ParticipantsFrom March 2009 to June 2011, a total of 1274 pregnant

women were enrolled in this study (Figure 1). Seven study

sites recruited between 119 and 329 participants each, rep-

resenting approximately 20–34% of all eligible women.

Baseline characteristics (Table 1) were similar in the two

intervention groups at trial entry; however, slightly more

women with two or more previous caesarean sections were

randomised to the 38-week group whereas more women in

the 39-week group had a maternal request caesarean. Four

women who were randomised did not fulfil the inclusion

criteria: two of these had no ultrasound-validated

gestational age, one woman was only 17 years old, and one

fetus had a planned NICU stay after delivery (39-week

group). One neonate (39-week group) died from congenital

pulmonary lymphangiectasia 11 days postpartum. The

intention-to-treat analysis included these participants. Only

data from two participants (one in each group) were not

included in the analyses of neonatal outcomes. Both had

induced vaginal delivery because of stillbirth.

A total of 1097 participants (571 in 38-week group ver-

sus 526 in 39-week group) had an elective caesarean deliv-

ery and 156 participants (59 in 38-week group versus 97 in

39-week group) had an unscheduled caesarean (within

8 hours of the decision). Among these, 49 women in 38-

week group (7.7%) and 82 women in 39-week group

(12.9%) had spontaneous onset of labour. Twenty-one par-

ticipants delivered vaginally (five in 38-week group versus

16 in 39-week group). Apart from one vaginal stillbirth in

each group, five out of 16 vaginal deliveries among women

in 39-week group occurred because of imminent delivery,

whereas the remaining ten women in 39-week group and

Elective CS assessed for eligibility (n = 4048)

Excluded (n = 2774)* Did not meet study criteria (n = 1380)

• No validated due date (n = 69) • Below 18 years of age (n = 11) • Needs interpreter (n = 152) • Multiple pregnancy (n = 269) • Likely to have CS before 39+5 weeks (n = 935) • Diabetes (n = 218) • Previously participated or too close to due date to

participate (n = 147) Met study criteria (n = 1394)

• Refused to participate (n = 849) • Logistics (n = 133) • Not asked (n = 165) • Information not available (n = 247)

1274 women randomised

Allocated to elective CS at 38+3 weeks (n = 636) Received allocated intervention (n = 591) Did not receive allocated intervention (n = 45)

• Logistics (n = 20)• Mother’s wish (n = 7)• Unspecified (n = 18)

Allocated to elective CS at 39+3 weeks (n = 638) Received allocated intervention (n = 567) Did not receive allocated intervention (n = 71)

• Logistics (n = 16)• Mother’s wish (n = 35)• Unspecified (n = 20)

All participants available to follow-up All participants available to follow-up

Included in the intention-to-treat analyses • 635 neonates (one stillbirth excluded) • 636 mothers

Included in the intention-to-treat analyses • 637 neonates (one stillbirth excluded) • 638 mothers

Figure 1. CONSORT Flow diagram. CS, caesarean section. *One woman can have more than one reason for not participating.

1126 ª 2013 RCOG

Glavind et al.

four women in 38-week group decided to deliver vaginally

because of spontaneous reversion to an occipital presenta-

tion or change of preferred mode of delivery after inclu-

sion.

Systematic registration of nonparticipants during the

inclusion period showed baseline characteristics similar to

participants in terms of age, body mass index, smoking

habits and previous vaginal births. Eligible nonparticipants

were more likely than participants to be nulliparous (27%

versus 19%), with no previous caesarean section (49% ver-

sus 40%), and to have a breech or transverse lie presenta-

tion (24% versus 16%).

Primary and secondary outcomesThe median difference in gestational age at delivery was

6 days (38+3; IQR 38+1–38+5 versus 39+2; IQR 38+6–39+5).Gestational ages at delivery in the two groups are illus-

trated in Figures 2 and 3. There was no significant differ-

ence in the primary outcome proportion as 88 of 635

neonates (13.9%) randomised to elective caesarean section

at 38 weeks of gestation were admitted to the NICU com-

pared with 76 of 637 neonates (11.9%) at 39 weeks of ges-

tation (Table 2). The relative risk (RR) of NICU admission

was 0.86 (95% CI 0.65–1.15) for elective caesarean section

at 39 weeks compared with 38 weeks, and the risk differ-

ence was � 1.9% (95% CI � 5.6 to 1.8). No significant

treatment by centre interaction was found for the primary

outcome (P = 0.57).

With respect to secondary neonatal outcomes (Table 2),

duration of treatment with continuous oxygen for more

than 1 day was significantly less frequent in the 39-week

group, with an RR of 0.31 (95% CI 0.10–0.94) and a risk

difference of � 1.4% (95% CI �2.7 to �0.2). After adjust-

ment for multiple comparisons, this association was no

0

50

100

150

200

<38+

0

38+0

38+1

38+2

38+3

38+4

38+5

38+6

39+0

39+1

39+2

39+3

39+4

39+5

39+6

>39+

6

Num

ber

of d

eliv

erie

s

Group 38+3 weeks: gestational age at delivery

Elective delivery

Unscheduled delivery

Figure 2. Gestational age at caesarean section in the 38-week group

in number of weeks + days (n = 630).

Table 1. Baseline characteristics of the study population

Elective

caesarean

section at

38+3 weeks

Elective

caesarean

section at

39+3 weeks

Maternal age in

years, mean (SD)

32.1 (4.4) 31.6 (4.6)

Maternal height in

cm, mean (SD)

167.7 (6.5) 167.6 (6.5)

Maternal pre-pregnant weight

in kg, median (IQR)

68 (50–86) 68 (49–87)

Body mass index �30 107 (16.8) 111 (17.4)

Maternal smoking 65 (10) 83 (13)

Gestational age

validated by ultrasound

before 15 weeks

636 (100) 636 (99.7)

Nulliparous 126 (19.8) 117 (18.3)

Previous caesarean

section births

0 253 (39.8) 255 (40.0)

� 1 383 (60.2) 383 (60.0)

Previous vaginal births

0 426 (67.0) 421 (66.0)

� 1 210 (33.0) 217 (34.0)

Gestational age at

randomisation

<32+0 weeks of gestation 279 (43.9) 290 (45.5)

� 32+0 weeks of gestation 357 (56.1) 348 (54.5)

Skin closure type*

Suture 63/628 (10.0) 64/621 (10.3)

Staples 565/628

(90.0)

557/621 (89.7)

Indication for

caesarean section**

Two or more previous

caesarean sections

128 (20.1) 102 (16.0)

Maternal disease/caesarean

section advised by

the physician

54 (8.5) 57 (8.9)

Breech or transverse

lie presentation

114 (17.9) 90 (14.1)

Previously complicated birth 78 (12.3) 83 (13.0)

Maternal request 262 (41.2) 306 (48.0)

Data are presented as number (*) unless indicated with mean (SD)

or median (IQR).

*Information missing for four women (two in each group) and not

applicable in 21 vaginal deliveries (six in 38-week group and 15 in

39-week group).

**Categorised according to most weighty indication for caesarean

section.

ª 2013 RCOG 1127

Timing of elective caesarean section: RCT

longer significant (adjusted level of significance 0.003).

There were no significant differences in the frequency of

NICU admission within 7 days of birth, respiratory mor-

bidity, or treatment with intravenous antibiotics. Similar

proportions were found in the two groups with respect to

NICU length of stay of � 2 days (Figure 4).

Among the neonates who did not receive respiratory

support (e.g. mechanical ventilation, nasal CPAP, oxygen

supplementation, or intravenous antibiotics), 12 neonates

in the 38-week group versus 11 in the 39-week group had

transitory tachypnoea or respiratory distress as their pri-

mary diagnosis. Apart from prematurity (five neonates in

the 38-week group versus three in the 39-week group), the

remaining reasons for NICU admission comprised a broad

range of categories in both groups, such as asphyxia (one

versus two), hypoglycaemia (three versus none), or various

suspected endocrine or haematological disorders. Two

neonates in the 39-week group compared with none in the

38-week group were admitted because of congenital malfor-

mations detected at birth.

Participants were defined as compliant if elective caesar-

ean section was performed within the randomisation group

dates or at any other date because of labour or complica-

tions in pregnancy, as any rescheduling among the last-

mentioned groups of women would be based strictly on

professional criteria. Accordingly, we performed a per pro-

tocol analysis with exclusion of 117 non-compliant and

four not eligible participants and found an RR of the pri-

mary outcome of 0.90 (95% CI 0.67–1.21). Finally, if

vaginal deliveries were excluded from the analysis, the RR

was 0.92 (95% CI 0.68–1.23).

With respect to secondary maternal outcomes no cases

of maternal death, hysterectomy, or serious thromboembo-

lic events were registered (Table 3). The risk of maternal

bleeding >500 ml was significantly lower in the 39-week

group (17.1%) compared with the 38-week group (21.7%)

with an RR of 0.79 (95% CI 0.63–0.99), but this finding

was insignificant after Bonferroni adjustment. The median

bleeding volume was 300 ml in each group. The number of

maternal adverse events was low in the majority of the

complications evaluated. We registered three versus one

case of uterine rupture or dehiscence (RR 3.04, 95% CI

0.31–29.13) and one versus four cases of injury to the

bowel or bladder (RR 0.25; 95% CI 0.03–2.26) in the 39-

week group versus the 38-week group, respectively. We also

found a similar risk of uterine incision lateral tear, proce-

dural difficulties, and bleeding needing further treatment in

the two groups. The risk of a composite maternal outcome

was similar in the two groups with proportions of 66/638

women (10.3%) in the 39-week group and 60/636 women

(9.4%) in the 38-week group (RR 1.1; 95% CI 0.79–1.53).No significant treatment by centre interaction was found

for the maternal composite outcome (P = 0.81).

Discussion

Main findingsIn this randomised controlled trial including 1274 pregnant

women, scheduling elective caesarean section at 39+3 weeks

compared with 38+3 weeks did not result in a significant

decrease in neonatal admission within 2 days of birth. In

addition, no secondary neonatal or maternal outcomes

improved significantly with late scheduling.

Strengths and weaknesses of the studyThe major strength of this trial was the randomised design,

which has, to the best of our knowledge, not previously

been used for investigating the association between gesta-

tional age at elective caesarean section and adverse perina-

tal outcomes. With an intention-to-treat analysis, the data

presented reflect the whole spectrum of consequences of

timing of elective caesarean from booking of the procedure

to birth of the child. The trial population was homoge-

neous, with approximately 95% being of white European

descent which in this case should be considered a strength,

as neonates delivered by White women in particular may

be vulnerable to performing the elective caesarean section

before rather than after 39 completed weeks of gestation.14

We had a 100% short-term follow-up rate, which among

other circumstances was related to the fact that if a neonate

required admission within 7 days postpartum, the neonate

was admitted to the NICU in the same hospital as the

delivery. Furthermore, a major advantage compared with

0

50

100

150

200<3

8+0

38+0

38+1

38+2

38+3

38+4

38+5

38+6

39+0

39+1

39+2

39+3

39+4

39+5

39+6

>39+

6

Num

ber

of d

eliv

erie

s

Group 39+3 weeks: gestational age at delivery

Elective delivery

Unscheduled delivery

Figure 3. Gestational age at caesarean section in the 39-week group

in number of weeks + days (n = 623).

1128 ª 2013 RCOG

Glavind et al.

previous studies was a due date validated by ultrasound in

99.8% of the participants.

With this trial we wanted to be able to assess the bal-

ance of potential adverse events or benefits of elective

caesarean section timing to the neonate and mother

according to the two timing interventions.3 Hence, NICU

admission that reflects a composite outcome as the pri-

mary outcome should be considered an advantage over

more specific measures. Although the decision to admit

a neonate relies on the physician, this decision is taken

on the basis of objective symptoms or signs necessitating

further observation or treatment, and no neonate would

be hospitalised without a clear indication. At the same

time, admission has implications for the families

involved, because it may lead to separation of mother

and child, anxiety and worries.

Some limitations to this study may apply. In terms of

serious events such as stillbirth, hysterectomy, thrombo

embolism, or death, the study was not powered to evaluate

the influence of elective caesarean section timing. In a

recent study, Rosenstein et al.15 found a similar risk of fetal

and neonatal death associated with delivery and expectant

management at 38 weeks, whereas at 39 weeks, delivery

carried a lower risk of neonatal death than expectant man-

agement. Hence, large observational studies would be of

value in this field. Another limitation to the current study

may be that the outcomes evaluated were all short-term. In

fact, delivery at 38 weeks may lead to increased healthcare

use in early childhood or increased risk of special educa-

tional school needs compared with delivery at 39 weeks of

gestation, but this association has not been investigated in

elective deliveries only.16,17

InterpretationBefore applying the results to other populations and set-

tings, several factors have to be considered. Overall, the

Table 2. Neonatal outcomes by intervention group: elective caesarean section (ECS) at 38 or 39 weeks of gestation*

ECS 38 weeks

(n = 635)

ECS 39 weeks (n = 637) Relative risk (95% CI) Unadjusted P value

Primary outcome

NICU admission within 48 hours 88 (13.9) 76 (11.9) 0.86 (0.65–1.15) 0.3136

Secondary outcomes

NICU admission within 7 days of delivery 101 (15.9) 89 (14.0) 0.88 (0.68–1.14) 0.3460

NICU length of stay � 2 days 39 (6.1) 38 (6.0) 0.97 (0.63–1.50) 0.9070

NICU length of stay in hours, median (IQR) 44.5 (42.2–46.8) 47.9 (45.6–50.2) NA 0.6995

Birth weight in g, mean (SD) 3369 (449) 3509 (511) NA <0.0001

Neonate male gender 324 (51.0) 329 (51.6) NA 0.8237

Apgar score at 1 minutes � 7 20 (3.1) 24 (3.8) 1.20 (0.67–2.14) 0.6458

Apgar score at 5 minutes � 7 6 (1.0) 12 (1.9) 1.99 (0.75–5.28) 0.2345

Umbilical artery pH at birth <7.10 5 (1.0) 6 (1.2) 1.24 (0.38–4.03) 0.7700

Standard base excess ��10 3 (0.6) 2 (0.4) 0.69 (0.12–4.13) 1.0000

Mechanical ventilator treatment** 1 (0.2) 4 (0.6) 3.99 (0.45–35.6) 0.3740

CPAP treatment 55 (8.7) 42 (6.6) 0.76 (0.52–1.12) 0.1711

CPAP treatment � 1 day 17 (2.7) 9 (1.4) 0.53 (0.24–1.18) 0.1178

Continuous oxygen supplementation 23 (3.6) 14 (2.2) 0.61 (0.32–1.17) 0.1307

Continuous oxygen supplementation � 1 day 13 (2.0) 4 (0.6) 0.31 (0.10–0.94) 0.0296***

Any respiratory morbidity**** 57 (9.0) 43 (6.8) 0.75 (0.51–1.10) 0.1459

Serious respiratory morbidity***** 11 (1.7) 9 (1.4) 0.82 (0.34–1.95) 0.6607

Intravenous antibiotic treatment 17 (2.7) 14 (2.2) 0.82 (0.41–1.65) 0.5916

Intravenous antibiotic treatment � 5 days 7 (1.1) 5 (0.8) 0.71 (0.23–2.23) 0.5788

Treated hypoglycaemia 5 (0.8) 5 (0.8) 1.0 (0.29–3.43) 1.0000

NA, not applicable.

Data are presented as number (%) unless otherwise indicated. Data were missing for neonates in the following categories: birthweight, one in

38-week group, base excess, 137 in 38-week group and 158 in 39-week group; pH, 135 in 38-week group and 152 in 39-week group,

hypoglycaemia, one in 38-week group and three in 39-week group.

*Two cases of stillbirth were not included in the intention-to-treat analysis.

**Duration was more than 1 day in all neonates treated with mechanical ventilation.

***Bonferroni significance level 0.05/18 = 0.003.

****Mechanical ventilation, continuous oxygen supplementation or CPAP during the NICU stay.

*****Mechanical ventilation, or three or more initiated days of treatment with continuous oxygen supplementation or CPAP during the NICU stay.

ª 2013 RCOG 1129

Timing of elective caesarean section: RCT

study population had a low body mass index and was very

homogeneous, and the study aimed to only include healthy

women with no a priori risks related to the neonate. In

addition, the eligible non-participating women may have

had a lower risk of an adverse neonatal outcome, because

they were probably booked closer to their due date (more

breech presentations) and fewer women were to have

repeat procedures.

The NICU admission rate was quite high compared with

those of other studies.8,9 This may be a consequence of all

neonatal admissions being included, whereas studies con-

ducted in facilities with differentiated levels of neonatal

care may have excluded neonatal admissions that were not

to the NICU. Comparing the incidence of a composite

adverse neonatal outcome after caesarean delivery at 38

and 39 weeks of gestation, Tita et al. 8,9 found an odds

ratio of 0.67 and Wilmink et al. found an odds ratio of

0.71 in favour of delivery at 39 weeks of gestation, which

are both estimates that lie within our calculated 95% CI of

0.65–1.15. Our primary outcome may compare with these

composites, which in our setting in each case would proba-

bly translate into NICU admission. Some of the excess

morbidity in our trial may be explained by prematurity or

unscheduled procedures because of complications or

labour. Still, these studies reported significant benefit of

elective caesarean section at 39+0–6 weeks compared with

1 week earlier, in opposition to the smaller (insignificant)

differences observed in our trial.8,9

In terms of maternal morbidity, the most interesting

aspect before the trial was whether more women with

spontaneous onset of labour in the late ECS group would

result in an increase in the number of women with infec-

tion or intraoperative complications because of the urgency

of the procedure. Apart from maternal intensive care

admission not being evaluated in our sample, the individ-

ual adverse outcomes otherwise assessed were comparable

Per

cent

age

in g

roup

15

10

5

038+3 weeks group 39+3 weeks group

<1 day 1–2 days≥2–7 days ≥7 days

Figure 4. NICU length of stay in days in neonates admitted within

48 hours of delivery. NICU length of stay proportion in 38-week group

versus 39-week group was � 1 day: 5.5% versus 4.4%; 1–2 days:

2.2% versus 1.6%; �2–7 days: 3.0% versus 3.1%; and �7 days:

3.1% versus 2.8%, respectively.

Table 3. Maternal individual and composite outcomes by intervention group: elective caesarean section (ECS) at 38 or 39 weeks of gestation

ECS 38 weeks

(n = 636)

ECS 39 weeks (n = 638) Relative risk (95% CI) Unadjusted P value

Uterine incision lateral tear 17 (2.7) 16 (2.5) 0.94 (0.48–1.84) 0.8622

Bowel or bladder injury 4 (0.6) 1 (0.2) 0.25 (0.03–2.22) 0.2173

Adherences, procedural or delivery complications 14 (2.2) 16 (2.5) 1.14 (0.56–2.31) 0.8538

Anaesthesia complications 2 (0.3) 7 (1.1) 3.49 (0.73–16.7) 0.1781

Rupture or dehiscence 1 (0.2) 3 (0.5) 3.0 (0.31– 28.7) 0.6244

Bleeding needing treatment or transfusion 9 (1.4) 12 (1.9) 1.33 (0.56–3.13) 0.6610

Reoperation* 10 (1.6) 6 (0.9) 0.60 (0.22–1.64) 0.3286

Antibiotic treatment within 30 days of delivery** 15 (2.4) 14 (2.2) 0.93 (0.45–1.91) 0.8537

Blood loss at delivery >500 ml 138 (21.7) 109 (17.1) 0.79 (0.63–0.99) 0.0399***

Composite maternal outcome**** 60 (9.4) 66 (10.3) 1.1 (0.79–1.53) 0.6391

Data are presented as number (%). Data were missing in the following outcomes: surgical outcomes: one case in 38-week group, two in 39-

week group; bleeding: nine cases in 38-week group, 11 cases in 39-week group; uterotonic perioperative medications: three cases in each group.

*Included in 38-week versus 39-week group: Evacuation (three versus two), wound revision (two versus two), and other operations (five versus

two).

**Included in 38-week group versus 39-week group: Endometritis (four versus one), wound infection (six versus five), and other procedure-related

infection (five versus eight).

***Bonferroni adjusted level of significance 0.05/9 = 0.006.

****Defined by any of the following events: uterine incision lateral tear, injury to bowel or bladder, procedural or anaesthesia complications,

rupture or dehiscence, bleeding needing additional treatment, re-operation, or antibiotic treatment.

1130 ª 2013 RCOG

Glavind et al.

with the composite outcome of Tita et al.10 We found a

higher proportion of composite maternal outcome in both

groups (9.4% versus Tita et al. 10 7.5% at 38 weeks and

10.3% versus Tita et al. 6.6% at 39 weeks), but similarly,

no difference was found between the 2 weeks of gestation.

This may reflect the fact that unscheduled caesarean sec-

tions were included in our population.

When this study was initiated, a substantial number of

elective caesarean sections in Denmark were scheduled

before 39 weeks of gestation. Recently published literature

on the timing of elective caesarean section almost uniformly

advises against elective caesarean section before 39 com-

pleted weeks.4,8,9,18–22 The risk estimates from this trial are

currently the only estimates available from a randomised

trial, and they could be interpreted in different ways. If the

power calculations overestimated the difference in NICU

admission between the two groups, this study would be

underpowered to detect a statistically significant difference.

Assuming a valid power calculation, our study has an 80%

chance that the findings were correct. We predicted (and

found) that 14% of the 38-week group neonates would be

admitted to the NICU, whereas the risk of NICU admission

in the 39-week group was almost 50% higher than expected.

This difference could be explained by an increased risk of an

adverse outcome in women who were delivered before their

scheduled date because of complications or labour. Interest-

ingly, the proportion of neonates with an NICU length of

stay >2 days was almost identical in the two groups. This

may indicate that even if more neonates were admitted with

elective caesarean section at 38 weeks, there was a similar

risk of severe neonatal morbidity in the two groups.

Our results could suggest that scheduling elective caesar-

ean section after the prevailing cut-off at 39+0 weeks of gesta-

tion may have less impact on short-term neonatal morbidity

than previously anticipated. In the mothers, timing of elec-

tive caesarean section at 38 or 39 weeks seems to carry a sim-

ilar risk of adverse events. Accordingly, scheduling of elective

caesarean section 3–5 days before 39+0 completed weeks may

be an acceptable option in women in whom an acute caesar-

ean section delivery should be avoided. Otherwise, schedul-

ing after 39 completed weeks may continue to be the best

option, until further trials support the evidence from this

study, and possible long-term consequences of elective cae-

sarean section timing are clarified.

Conclusions

In conclusion, elective caesarean section scheduled after

39 weeks of gestation versus before 39 weeks carried a

similar risk of neonatal special care admission. The inci-

dence of other adverse neonatal and maternal outcomes

was similar in the two groups. Any long-term consequences

to the neonate or mother of elective caesarean timing at

term are uncertain and need further investigation.

Disclosure of interestsThe authors have no conflicts of interest.

Contribution to authorshipJG, SFK, NU and TBH had the idea for the study and were

responsible for the data analysis. JG was the principle inves-

tigator and wrote the first draft of the protocol and the

manuscript. JG, SFK, NU and TBH contributed to the gath-

ering of data from the University Hospital of Aarhus and

were responsible for the overall supervision of the trial man-

agement. MK was the responsible investigator at the Hospi-

tal in Kolding. AMM was the responsible investigator at

Aalborg University Hospital. BBM was the responsible

investigator at the Regional Hospital of Viborg. OBR was

the responsible investigator at the Regional Hospital of Ran-

ders. JTC was the responsible investigator at the Regional

Hospital of Herning. JSJ was the responsible investigator at

Odense University Hospital. Guarantors for the study were

JG, NU and TBH. All authors had full access to the data in

the study and take responsibility for the integrity of the data

and the accuracy of the data analysis. All authors reviewed

and approved the final version of the paper.

Details of ethics approvalThe study was approved by The Central Denmark Region

Committees on Biomedical Research (ID M-20080142).

FundingThe study was supported by grants from The Danish

Council for Independent Research Medical sciences, Health

Research Fund of Central Denmark Region, The Philan-

thropic Foundation TrygFonden, Aase and Ejnar Daniel-

sen’s Foundation, Sophus Jacobsen’s Foundation, Dagmar

Marshall’s Foundation, Marie Dorthea and Holger From,

Haderslev’s Foundation. The funders of the study had no

role in study design, data collection and analysis, or prepa-

ration of the manuscript.

AcknowledgementsWe wish to thank all the families who participated in this

trial, the dedicated staff from all participating departments,

and our trial steering committee members.&

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