Most of us accept the "no pain,
no gain" rule -- after all, nothing worthwhile achieving
is ever easy. Try explaining this to a woman in labour
though and you're likely to get your head bitten off.
Of course, most women would rather do without the agony,
but numerous studies suggest that receiving an epidural
to numb the pain in early labour increases the likelihood
of a cesarean section delivery. So, although an epidural
controls pain better and doesn't result in the nausea
and vomiting associated with opiates, if mom wants a natural
birth she's going to pass on this option. Recent research
suggests, however, that we may have been too quick to
judge this pain treatment.
DEFECTIVE
DATA?
Suspicions that the anesthetic may be linked to higher
rates of c-sections led the American College of Obstetricians
and Gynecologists to recommend that epidural analgesia
be delayed in women who have not previously given birth
until their cervix dilates to 4cm. However, a study
in the February 17 issue of the New England Journal
of Medicine argues that previous research was based
on flawed methodology, and in fact epidural anesthesia
is less likely to result in c-section than opiates.
Researchers from Chicago's Northwestern
University randomized 750 nulliparous pregnant women
to receive either spinal fentanyl or systemic hydromorphone
at their first request for anesthesia. The fentanyl
group continued to receive that drug, while the opiate
group was only given fentanyl on their second request
if they met the criterion for a sufficiently dilated
cervix. If they didn't, they received fentanyl only
on their third request.
Contrary to conventional wisdom,
the fentanyl group did not experience more cesarean
deliveries than the opiate group. In fact, they were
fractionally less likely to require c-section, requiring
18 such operations compared to 21 in the opiate group.
Moreover, the fentanyl patients
progressed more rapidly to complete dilation, taking
an average 398 minutes compared to 479 minutes in the
opiate group. This finding runs directly counter to
those of previous studies.
"That was a surprising finding,
and I'm not sure how to account for that one," said
lead author Dr Cynthia Wong, an anesthesiologist at
Northwestern. But she believes that previous studies,
which were all retrospective, failed to account for
some hidden risk factor that linked the patients who
received early epidural anesthesia to increased risk
of later c-sections.
PAINFULLY
OBVIOUS
"I think the key is pain, possibly linked to large babies,
babies the wrong way round, and babies in awkward positions.
There's plenty of research suggesting that women who
ask for anesthesia earlier in labour are more likely
to undergo cesarean."
The logic is forehead-slappingly
obvious, but the simple answer has somehow eluded us
until now. If women are in more pain, they're more likely
to request anesthesia early in labour, and more likely
to get epidural anesthesia, which better controls pain.
Ergo, they will generally experience a longer delay
from anesthesia to dilation, not because the dilation
began late, but because the anesthesia began early.
And it stands to reason that women who are in greater
pain are more likely to request a cesarean. Failure
to control for these factors has led us to wrongly blame
the anesthetic itself. It may be time to revisit the
guidelines.
NEJM Feb 17, 2005;352:655-65
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