19 Oct Delivering Twins
Are you expecting twins and want to know more about your birthing options? Here is a guide to delivering twins.
One of the elements in the decision about which will be the best method of delivery is the position –or ‘presentation’ – of the babies in the womb during the third trimester.
Presentation will have been recorded at each of your antenatal appointments and is confirmed by scanning (establishing this by abdominal palpation alone is difficult in a twin pregnancy). Babies can be positioned longitudinally (vertical), horizontally (transverse) or diagonally (oblique) and this is termed the ‘lie’.
In a longitudinal lie, each baby’s presentation is determined by the part of its body that is closest to the pelvis: it can either be vertical head down (cephalic) or vertical bottom first (breech). Hence, with twins, there are seven variations of presentation and lie.
The method of delivery chosen depends on the presentation of the first twin and the various options will be discussed with you. The breech presentation increases the risk of complications in a vaginal birth. The largest part of the body, the baby’s head, comes last, and there is a chance that it could be difficult to deliver. Furthermore, the umbilical cord can prolapse, meaning that it slips out from underneath the body of the descending baby and emerges from the vagina. Exposure to air then causes the cord to constrict, thus depriving the baby of oxygen. It can also be intermittently compressed by the passage of the baby’s body as it descends through the vaginal canal, which also restricts the oxygen supply during the delivery. If both twins are cephalic, then vaginal delivery has a high chance of a safe outcome.
If the first twin is cephalic and the second non-cephalic (i.e. breech or transverse/oblique), then the second twin can be delivered either as a vaginal breech, by trying to turn the baby to a cephalic presentation (less likely) or by Caesarean section. If it is the presenting twin that is breech and complications arise during labour, the consequences for both babies, and for the mother, could be very serious. So if the first or both babies are presenting in a non-cephalic way, then a Caesarean section will be offered.
Although it is important to assess each baby’s presentation throughout pregnancy, this can change right up to and during labour itself, especially for the second twin, which is why a decision on what sort of delivery to have can only ever be made with the information available at the time.
This is an excerpt from Expecting Twins? by Professor Mark Kilby, Jane Denton and Debbie Beckerman, published by Hardie Grant Books, $34.95.
Words by Debbie Beckerman