Bringing on baby
Are you desperate to get that baby out, no matter
what it takes? Dr Anil Sharma explains what it means to have labour
induced.
While the majority of pregnant women will go into labour
spontaneously, around one to two in 10 women need a bit of help.
Most pregnancies last for around 40 weeks, but some will go
overdue, or perhaps there will be another medical issue that means
induction is necessary. While some pregnancies are induced for
social reasons or by maternal request, induction of labour involves
an interventional process and by and large it should be undertaken
for valid reasons. In other words, when induction is undertaken,
ideally it should be because carrying on with pregnancy involves
greater risk to the mum-to-be or baby (or both) than the process of
induction. Having had a previous Caesarean section does not mean
that induction is not possible, but the pros and cons need careful
consideration, as the risks of uterine scar rupture in labour are
slightly higher than with natural labour.
This article is a general guide to
induction of labour. Detailed assessment and discussion with your
own lead maternity caregiver (LMC) is advised.
During pregnancy, but especially towards
the end (by around 38 weeks), your LMC should have discussed
labour, induction, and other types of deliveries with you. This
will involve information about the risks associated with
pregnancies that last longer than 42 weeks, and their
options.
Reasons for induction
The most common reason is due to your pregnancy going "post-dates",
which usually means going beyond 41 weeks and 4 days pregnant.
Other reasons include medical problems of pregnancy, including
pre-eclampsia (a syndrome that usually involves blood pressure),
slow growth in the baby, or unexplained pain or bleeding at
term.
How an induction happens
Once the decision to undertake an induction of labour is made, the
biggest physical hurdle is overcoming the resistance to birth by
the cervix. After all, the normal cervix is thick, long, and
closed, and has helped keep the baby inside the uterus.
Normally, the cervix gradually softens,
shortens, and starts to dilate as the pregnancy gets ready to end
and labour is just around the corner. Some chemicals called
prostaglandins are released naturally to help these changes
occur.
If the cervix is still "unfavourable" for
labour, a prostaglandin (Prostin) gel is inserted into the upper
vagina. This gradually helps bringing about the changes noted
above. This aim of changing the cervix can take around four doses
of Prostin, and this is done gradually over two days or
thereabouts. A number of tests are undertaken during this
time to make sure the baby (and mum-to-be) don't have any side
effects due to the Prostin.
Once the cervix is significantly changed,
the bag of waters (the membranes) can be broken (this is called
amniotomy). The Prostin may work quicker, needing less than four
doses, but occasionally more than this is needed. While this whole
process can be long and arduous (not least because the whole family
is very excited about the arrival!), it pays to remember that the
natural means of getting the cervix ready usually takes weeks, not
days.
The induction process takes place in
hospital under careful conditions. If and when you need pain
relief, this is organised just as it is for natural labour.
Oxytocin is secreted by part of the brain into
the bloodstream, and causes the actual contractions of labour to
occur. Syntocinon is the laboratory-made version of oxytocin, and
is used to start the uterus contracting (once the waters have been
broken). It is given by a drip into a vein, but this also means
that it can be increased or decreased, or even stopped if
necessary.
Amniotomy (breaking the waters)
This process is usually not as painful as it sounds. It is
undertaken with a small hook (like a crochet hook) during an
internal examination. After the waters are broken, it is usual to
start syntocinon to get contractions started. Sometimes, however,
especially if you have had a baby already, your obstetrician
or midwife may suggest you get up and about (mobilise) for a few
hours to see if you start contracting on your own.
Pain relief during induction
While it is a commonly held belief that induction is more painful
than natural labour, this is not proven. What is, however, logical
is that the process of going from not-in-labour to labour is faster
with induction than natural labour. It is therefore no surprise
that the pain that is associated with this is greater than a
gradual onset of pain over days.
All the usual methods of pain relief in
labour, including epidurals, are fine in induced labour, but
epidurals are best reserved for when you are actually in labour
(more than 3cm dilated).
Membrane sweeps and other induction methods
This involves an internal examination, and a gloved index finger is
then passed into the cervical canal to stretch and sweep the area
where the membranes are in approximation to the upper part of the
cervix. This has the effect of releasing the natural prostaglandins
as discussed above.
Membrane sweeping makes spontaneous labour
more likely, and reduces the need for formal induction of labour to
prevent prolonged pregnancy.
Discomfort and slight vaginal bleeding are
possible from the procedure, but usually well-tolerated by the
mum-to-be. Membrane sweeps are commonly used in the UK, and their
advantages are becoming more apparent in New Zealand.
Despite widely held beliefs about
acupuncture, homeopathy, herbal supplements, castor oil, hot baths,
enemas, sexual intercourse, or eating hot curries, there is
unfortunately no actual good evidence to support their use as
agents for the induction of labour. Try any or all of the above if
you want to, but don't be surprised if you end up in the bathroom
with a tummyache.
If induction doesn't work…
If induction does not work, again it becomes an issue of weighing
up the pros and cons of the options specifically for you and your
pregnancy circumstances. It may be that further use of Prostin is
thought to be reasonable, but the only other option is delivery by
Caesarean section.
Women who do not wish to have an induction
when offered will need to raise their concerns with their LMC. In
the case of declined induction for post-dates pregnancy, the risks
will need to be discussed and if you accept the small risk of
serious outcome, then the pregnancy can continue. However, it would
be advised that frequent foetal heart rate monitoring and
ultrasound scans to check for foetal wellbeing should be
undertaken.
Induction of labour is a necessary
intervention, as nature sadly doesn't have all the answers. It also
involves small risks to fetal wellbeing, and risks of other
intervention such as Caesarean section.
Because induction does involve significant
interference and other risks, ideally it should only be carried out
if the risks of leaving the pregnancy to proceed are greater than
the risks of induction. However, when used in appropriate
circumstances, induction of labour is a well-tolerated and accepted
means of achieving safe vaginal delivery.
Dr Anil Sharma is a specialist doctor in
gynaecology and maternity. He is very involved in lectures and
updates for family doctors and frequently takes part in debate
regarding women's health and maternity for print media and radio.
He believes that anxiety and fear can be conquered by knowledge.
Anil immigrated to New Zealand from the UK in 2001 with his wife,
Rachel, and he tries hard to be a hands-on and fun father (putting
golf and cars on hold for the time being) to their three daughters,
who were all born here. Anil has his own website,
www.dranilsharma.co.nz, which has further
details about his practice.
As seen in OHbaby!
magazine Issue 9: 2010
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