In breech presentation, most obstetricians agree that an above-average weight fetus is best delivered by caesarean section. If, on an ultrasound scan, the baby is estimated to weigh 4 kg (81b 10 oz) or more, then the majority will advise a caesarean section. In fact, for a first pregnancy, the cut-off point is lower for most obstetricians, probably around 3.5 kg. Even in these countries, the ultra-cautious obstetrician will perform a caesarean section for all first-time mothers with a breech presentation.
How does the type of breech influence the decision on the method of delivery?
We have seen that there are three main types of breech presentation: frank (where the legs are extended), footling and complete (flexed leg).
The most common type of breech, which is where legs are extended (frank), is considered the most ideal for vaginal delivery, as it is the one least associated with cord prolapse. On the other hand, about one in ten (10%) footling breech presentations will be complicated by cord prolapse. The figure is about one in twenty five (4%) for complete breech where legs are flexed.
Many obstetricians consider footling breech reason enough to recommend a caesarean section as soon as it is recognized. Again, where breech vaginal delivery is practised, this is only a relative indication and there is room for alternative opinions.
What is cord prolapse?
This is a state where the ‘waters’ break and the umbilical cord protrudes through the cervix. The cervix is normally incompletely dilated, and consequently the cord is compressed, causing acute fetal distress.
Cord prolapse requires immediate caesarean section to save the baby - unless it occurs when the cervix is fully dilated and vaginal delivery can be achieved almost immediately. This latter situation is rare.
Can the cord prolapse accident be prevented?
In managing labour in breech presentation, the membranes (waters) are left intact for as long as possible. This helps to dilate the cervix and reduces the risk of a cord accident (prolapse). However, sometimes the membranes break spontaneously, and these are the circumstances where footling breech is particularly risky whereby the leading foot and leg as well as a loop of cord may protrude through the incompletely dilated cervix. If this were to happen, an emergency caesarean section will be performed.
It appears as if obstetricians prefer to deliver breech babies by caesarean section.
It is not a question of preference but of being realistic.
It is a known fact that the risk of vaginal breech-delivered babies dying just before or after the birth is almost 10 times as high as those presenting with the head. Even morbidity is five times higher. Admittedly, most of this is influenced by prematurity and the higher incidence of major abnormalities for these babies. The increased morbidity and mortality is therefore not wholly due to the breech vaginal delivery per se.
With all that in mind, most obstetricians would want to err on the side of caution. This is why most breech presenting babies are delivered by caesarean section. As mentioned earlier, in some countries, including the UK, all term breech babies are routinely delivered by caesarean section.