Discussion
Principal findings
This study analysed expectant management versus induction of labour at
39 weeks of gestation in women 40 years of age or older at the time of
delivery. In older women, active labour management resulted in better
perinatal outcomes without increasing the caesarean section rate and
with similar vaginal delivery rates compared to expectant management.
Results in the context of what is known
The number of published studies on pregnant women of advanced maternal
age is scarce. Most of the studies on induction of labour at term
involved women with established complications, such as hypertensive
disorders8 rupture of membranes9,
foetal growth restriction10,11,
diabetes12, or foetal macrosomia13.
The 35/39 study was a randomised clinical trial designed to test the
hypothesis that induction of labour at 39 weeks of gestation would
reduce the rate of caesarean delivery among nulliparous women of
advanced maternal age. Their data showed that induction of labour at 39
weeks of gestation, as compared with expectant management, did not
increase caesarean delivery.14
The study by Knight et al included a total of 77,327 women aged 35
years. They found no statistically significant difference in the
caesarean section rate between the 39-week labour induction groups and
the expectant management group (Adjusted relative risk: 1.04, confidence
interval [CI] 95%: 0.99–1.01).15 In 2019, a
retrospective cohort study including 35-year-old nulliparas with
singleton gestations at term comparing elective induction at 37, 38, 39
and 40 weeks’ gestation and those with expectant management at the same
number of weeks found that induction at 39 weeks’ gestation was
associated with decreased odds of caesarean section delivery (Ora 0.69;
CI95%, 0.53-0.91).16 Our data supported previous
studies and found no statistically significant difference in the type of
delivery between the expectant management group and the induction at 39
weeks group. In the secondary analysis of the type of delivery according
to parity, we found no significant differences in the route of delivery
among the groups studied. In the expectant management group, the
subgroup of women aged 40 years at 39 weeks of gestation and without any
previous type of delivery (vaginal or caesarean) included 227 patients,
of whom 24.2% had vaginal deliveries and 41.4% had operative vaginal
deliveries. This meant that 65.6% of deliveries were vaginal delivery
versus 34.4% of deliveries by caesarean section. In the active
management group, the group of patients with the same characteristics
was made up of 252 women, of which 69% delivered vaginally (32.9%
vaginal delivery and 36.1% operative vaginal delivery) as opposed to
31% of deliveries by caesarean section.
Our data showed a rate of successful TOLAC similar to the 62.3%
reported in previous studies.17
Another main finding was better neonatal outcomes in the labour
induction group than in the expectant management group. The need for
paediatric support at birth, the type of neonatal resuscitation
measures, and the NICU admission rates were lower in the labour
induction group than in the expectant management group. These data
support the results of study lines in which perinatal outcomes improved
with elective induction at 39 weeks of gestation.16,18
Finally, another result to highlight is the 0% stillbirth in the active
management group versus the two intrauterine foetal deaths recorded in
the expectant management group. These differences were not statistically
significant because intrauterine foetal death is a rare adverse outcome,
and a large sample size would be needed to find significant differences
between the groups.
Research implications
There is a continuous risk for both the mother and baby with increasing
maternal age, with numerous studies reporting multiple adverse foetal
and maternal outcomes associated with advanced maternal age. Women ≥ 40
years of age had a similar stillbirth risk at 39 weeks of gestation with
younger women at 41 weeks of gestation. Induction of labour at 39 weeks
of gestation reduced these adverse outcomes. However, at present, there
are insufficient data available on the effect such a policy would have
on caesarean rates and perinatal outcomes, specifically in older women.
Our study analysed the effect of labour induction compared with
expectant management in women over 40 years of age. Our results provided
data on intrapartum complications, mode of delivery, neonatal morbidity,
and late stillbirth.
Strengths and limitations
Our study has several limitations. The definition of advanced maternal
age in the literature varies with publications using different criteria.
The definition used in our study aligns with the hospital’s definition
of ≥40 years. The major limitation of our study was its retrospective
nature. The retrospective dataset was subject to incomplete data entry
and variation in practice. Despite our limitations, there are only a few
studies in the literature that evaluated obstetric and perinatal
outcomes according to active or expectant management in pregnant women
of advanced maternal age and consider parity within their data.