The ideal
time for delivery in low risk pregnancies has been debated since very long.
ACOG efforts to stop elective induction before 39 weeks in well dated
pregnancies have decreased neonatal morbidity and mortality. So, this year’s debaters for The Edith Louise Potter Memorial Lecture at the ACOG annual conference tried to answer a difficult
question by offbeat approach: If recommendation say no elective induction
before 39 weeks, why not induce every well dated patient at 39 weeks?
The debaters
were Dr. Errol Norwitz, MD, PhD, chairman of the Department of
Obstetrics and Gynecology, and professor at Tufts University School of Medicine
and Dr. Charles Lockwood, MD, senior vice president, USF Health, dean of the
Morsani College of Medicine, University of South Florida, professor of
obstetrics and gynecology at Morsani College of Medicine, and professor of
health policy and management at the College of Public Health, University of
South Florida.
Interestingly
both the debaters agreed that continuing pregnancy beyond 39 weeks is risky for
the fetus.
Several
studies from USA and UK were cited to support the argument. Dr Norwitz said “Continuing
the pregnancy beyond 39 weeks is riskier than previously believed for the
fetus. In addition, risks to the mother associated with routine induction
"are lower than appreciated."
Dr. Lockwood
also seconded the opinion saying "I was absolutely opposed" to the
elective induction of labor at 39 weeks but after much reading it's
overwhelmingly evident that elective induction of labor is the logical
strategy."
Dr Norwitz
stressed that higher rates of stillbirths after 39 weeks have been known since
1980’s but the research was always overlooked. According to a study published
in BMC Pregnancy Childbirth. 2015; 15(Suppl 1): A11 late stillbirths (pregnancies
28 weeks or later) occur twice a common as deaths due to congenital anomalies;
twice as common as deaths due to preterm complications, and ten times more
common that Sudden Infant Deaths.
Another
retrospective study of 171,527 notified births published in BJOG, evaluated
gestation-specific risks of stillbirth, neonatal and post-neonatal mortality.
The study concluded that with each passing week the risk of still births and
neonatal mortality increases by nearly 11 fold to that at 37weeks. Multiple factors like the effects of parity, multiple pregnancy, congenital
abnormality, meconium aspiration and uteroplacental insufficiency may be responsible for it but,
requires further detailed analysis.
Several
other studies and meta-analysis have reiterated these findings.
The major
risk factor for induction at 39 weeks is failed induction leading to an
operative intervention, but surprisingly both Dr. Norwitz and Dr. Lockwood did
not see any increased rate of cesarean delivery, albeit they found a
decrease. Because of paucity of data on
routine induction at 39 weeks, Dr Norwitz extrapolated data from IOL vs.
expectant management (EM) at 41 weeks and it showed a decrease in cesarean
section rate.
He and his
colleagues performed a
comparative-effectiveness analysis and the model consisted of 60 probable outcomes. The
team then also created a Monte Carlo microsimulation to map out head-to-head
effectiveness.
It was seen
that expectant management were associated with higher operative intervention and
clear increase in perinatal mortality.
Maternal rates were the same for the two groups, but complications rates
were more for mother and infant in the expectant management group.
To conclude
Dr Lockwood said “elective IOL at 39
weeks was always the superior decision strategy to expectant EM with IOL at 41 weeks.”
Both the debaters agreed that to induce
the patient successfully at 39 weeks requires accurate gestational dating otherwise
it may not be beneficial as planned.
References:
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