At the beginning of the third trimester, you will have a discussion with your healthcare professionals regarding your choices about the birth. As your due date approaches, you will need to decide together as to the best time to deliver your babies and which will be the safest method.

Approximately 50–60 per cent of women carrying twins deliver spontaneously before 37 weeks. If you have not gone into labour as you approach the end of the third trimester, the timing of the birth will need to be discussed with you.

All women expecting twins are offered the opportunity to have their babies at 37 weeks (36 weeks for monochorionic (identical) twins, after steroids have been administered to help the babies’ lung function). This is because the placenta works less efficiently after this time, which means the babies will no longer be receiving enough oxygen and nutrients. If a monochorionic (identical) (MC) pregnancy is complicated in any way, it is likely that delivery will be advised at 34–36 weeks.

Delivery may also be advised earlier than 37 weeks if:

  • the health of your babies in the womb is found to be deteriorating
  • your membranes rupture (‘waters break’) but you do not spontaneously go into labour within 24 hours
  • you are suffering from pre-eclampsia or diabetes.
  • If you prefer to continue with the pregnancy for longer or want to wait for labour to begin naturally, you will need further close monitoring until delivery because of the increased risks of babies dying in the womb after 38 weeks.Once the timing of the delivery has been decided:You will need to discuss the most appropriate method of giving birth: vaginal labour or Caesarean section. This is decided medically on standard principles based upon the presentation of the first twin. There may, however, be other issues, such as your overall health and that of the babies, which will determine which method may be preferable.For example, in babies with an estimated fetal weight that is either small (less than 1,500 g) or large (more than 4,000 g), the merits of attempted vaginal birth versus Caesarean section will be discussed with you. A Caesarean section may also be advised for MC pregnancies with complications.Those that are also monoamniotic (identical twins in one amniotic sac) are almost always delivered by Caesarean section at 32–34 weeks to reduce the risk caused by cord entanglement.This is an edited extract from One Born Every Minute: Expecting Twins? by Professor Mark Kilby and Jane Denton (Quadrille, £25).Text © 2013 Mark Kilby and Jane Denton