Twins and multiple births

The birth of more than one baby is always known as a multiple birth, whether there are two, three or more. One baby at a time is known as a singleton.

Multiple birth – the statistics

  • one pregnancy in every 80 is a twin pregnancy
  • one pregnancy in 8,000 is triplets
  • one pregnancy in 800,000 is quads.

Twins – how pregnancy and birth are different

Twins (and more) are formed either by the egg splitting shortly after fertilisation identical twins) or by two or more eggs being fertilised by two or more sperm (non-identical or fraternal twins). Non-identical twins are slightly more likely to happen after a course of fertility treatment which stimulates ovulation, and which means more than one egg may be released. They can also happen when more than one fertilised egg is put into the uterus after in vitro fertilisation (IVF – test-tube pregnancy).

Twins will show up on the screen during an ultrasound scan. They may be suspected if your uterus is larger than expected at this stage of pregnancy. For lots of parents, finding out you're expecting twins can come as a shock and you may find it hard to cope with the thought of looking after more than one baby.  

With multiple pregnancy, minor discomforts may also be heightened. That means (for example) more backache, fatigue, heartburn and nausea, constipation and piles. The increased weight gain and the excess of pregnancy hormones contribute to this. You will need all the support you can get. Your midwife will be able to reassure you and help you find the right supports for you and your family.

Extra care

If you are expecting twins, or more, you will receive more attention during pregnancy. The reasons for extra care include

  • a greater chance of high blood pressure, which needs careful observation and possible treatment
  • the fact that twins, or more, are likely to be born before 40 weeks – 37 or 38 weeks is average for twins, but 25% of twin pregnancies lead to birth before 36 weeks
  • a greater likelihood of birth problems
  • you may be encouraged to consider having a scheduled Caesarean section, particularly if one of both twins is in a position which would make vaginal birth difficult or impossible
  • the second twin may need help to turn if you choose to have vaginal births
  • you may need a Caesarean section to deliver the second twin if he or she needs to be born quickly
  • it’s very unlikely that vaginal birth will be possible if you’re expecting triplets.

Even so, while multiple pregnancy is hard work, and a multiple labour and delivery may be more of a challenge to everyone, especially you, the majority of twin and triplet births are as joyous and rewarding as any other, and many pregnancies and births are perfectly straightforward.


Twins in the uterus – how do they lie?

The best presentation of twins is with both lying head-down – ‘cephalic’ or ‘vertex’ – and this is the most common. However, pressure on space in the uterus means it’s also quite common for one or both babies to be breech (feet or bottom down). A transverse lie (baby across the uterus) is also a possibility and, if this is the case with the first presenting twin, a Caesarean section is inevitable. If the first twin has been born vaginally but the second twin is lying across the uterus, there may be an attempt to turn the second twin.

See the TAMBA website, the Twins and Multiple Birth Association for more information.

Last Updated: 22 January 2018
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