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Pregnancy Bliss | Reproductive Health Hub

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Labour after a prolonged pregnancy


How is labour induced?
This may be by using some form of a prostaglandin preparation - usually a gel or pessary, vaginally. This  is to prime the cervix, allowing it to open easily in labour.
If the cervix is already favourable, induction will be in the form of breaking the waters (membrane rupture). This, in itself, may be sufficient to trigger contractions. More often, an infusion of an oxytocin hormone is required to bring about contractions.
See Chapter 35, "Induction and augmentation of labour", for more details.


If an expectant mother requests a caesarean section for prolonged pregnancy, can this be granted?
Most obstetricians frown upon caesarean section on demand, and rightly so. Prolonged pregnancy per se is not an indication for caesarean section and the obstetrician will be within his or her rights to decline such a request. In fact, by declining to perform a caesarean, he or she will be doing the expectant mother a favour, even though it won't be perceived that way at the time. After all, the obstetrician is acting in the mother's best interests. It is a dangerous fallacy to perceive caesarean section as a risk-free undertaking.  
  

How likely is prolonged pregnancy to recur?
It appears that this mostly happens in first pregnancies. The majority of mothers will not get it again. It is estimated, however, that up to a third will have a similar experience in a subsequent pregnancy.


Can prolonged pregnancy be predicted in the antenatal period?
No.


Is there any natural way of expediting the onset of labour if prolonged pregnancy is threatening?
Sexual intercourse to bring about the onset of labour is the stuff of folklore. There may be something in the claim, considering that semen is rich in prostaglandins, but this has never been proven scientifically - probably because setting up such a study would be rather tricky. For more details on this subject, go to: Induction of labour: Can you 'DIY'?



What role a 'membrane sweep'?
A membrane sweep is performed by performing a vaginal examination. If the cervix is partially open to allow a finger through, this is inserted and swept around to separate the bag of amniotic fluid from the inner wall of the cervix. This is thought to facilitate release of prostaglandins which are responsible for triggering labour. There is solid evidence that, in some cases at least, this succeeds in setting labour off. Many obstetricians advocate the use of this method once a woman has gone past her due date.


Is there anything special about amniotic fluid volume and prolonged pregnancy?
As a general rule, amniotic fluid volume starts to decline around about 38 week of pregnancy. In prolonged pregnancy, reduced amniotic fluid volume is common. This, combined with the ever-increasing fetal size and weight, means there is less and less room in the uterine cavity. Because of all that, movements may be perceived less during this time. More importantly, the risk of cord compression is increased. If, during the routine fetal surveillance at around 41 weeks, the amniotic fluid is found to be significantly reduced, intervention in the form of labour induction may be advised by many obstetricians. In any case, this is around the time when  induction of labour will be advised anyway.


What is an amniotic fluid index (AFI)?
It is a way of estimating the fluid volume, using an ultrasound. It is a standardized way of measuring the volume which has been found to be reasonably objective, though not infallible. An equally useful way of estimating fluid volume is by measuring the deepest pool of water in the womb.


Is labour after a prolonged pregnancy in any way special?
Yes. Labour after a prolonged or post-term pregnancy is no longer low-risk. Because of this, many obstetricians would prefer to have continuous electronic fetal monitoring (cardiotocograph). However, in the absence of other detectable risk factors, others will be content with intermittent monitoring, provided the first hour or so at the establishment of labour has shown a satisfactory trace of the baby's heartbeat and the expectant mother wishes to have this kind of monitoring. When this is adopted, the monitoring will be performed for about thirty minutes every two hours or so. There are no strict rules about this.

Expected date Term After 42 weeks Predisposing factors Fetal wellbeing Labour in postmaturity