Twin birth rates are declining in the UK

Twin birth rates are declining in the UK: here’s why

Data from Statista has revealed an 11% decline in multiple births in the UK since 2015. What’s more, the Human Fertilisation and Embryology Authority has found that the UK average IVF multiple birth rate has reached the lowest level yet in recent years and has reduced by at least 28% since the 1990s.

According to data from the Twins Trust, around 1 in 65 pregnancies results in a multiple birth in the UK. This number had previously been growing as a result of fertility treatments and women starting their families later on in life.

However, a reduction in fertility treatment during the coronavirus pandemic and changing approaches with regards to how many embryos are transferred to the uterus of a patient during IVF could both be causes for the dropping rates.

Since 2000, some experts have discouraged multiple embryo transfers in a bid to prevent risky pregnancies. Since 2004, in the UK, there has even been a limit as to how many embryos can be transferred.

What makes a twin?

A person can be considered a twin if they were formed alongside their sibling in the womb during a single pregnancy.

Many people will have heard about identical and fraternal (non-identical) twins.

Fraternal or non-identical (dizygotic) twins are the most common twin type worldwide and are formed when two separate eggs are fertilised by separate sperm. The fertilised eggs then implant in the uterus, resulting in two babies from the same pregnancy. Non-identical twins can be the same sex, or different sexes (one boy and one girl).

However, identical (monozygotic) twins will always be the same sex, as they are formed when a single fertilised egg splits, creating two embryos that share near-identical genes.

A twin DNA test – also called a zygosity test – is a DNA test that can be used to determine whether multiple children from the same birth (twins, triplets, quadruplets etc.) are identical or non-identical.

Why might you want a twin DNA test?

There are many reasons why you might want to order a Twin DNA Test.

Examples include:

  • It wasn’t clear during pregnancy (in utero) whether the twins were identical or non-identical. Identical twins do not always share the same placenta and sac – it all depends on when the egg splits
  • You want to assess the likelihood of conceiving twins again
  • One sibling has been affected by an illness, and you want to know whether you need to test the other sibling for the same condition
  • You need the information to take part in a study about multiple births
  • You want to buy a Twin DNA Test as a gift for multiple birth parents or their children

Where can I buy a Twin DNA test?

Thanks to advances in modern scientific techniques, it’s never been easier to find out for sure whether twins are identical or not.

For just £99 and with next-day results, our home Twin DNA test can be ordered quickly and easily online, and gives families the expert answers they need from our award-winning and UKAS-accredited laboratory.

With only simple cheek swabs required, this easy and completely painless test can be used on siblings of any age – from newborn babies to grown adults. The DNA (zygosity) certificate provided on completion of the test can also be used as a unique keepsake for multiple birth parents.

Need to know more about our Twin DNA test? Call our friendly and knowledgeable Customer Services team on 0333 600 1300 or email

Order a DNA Test

View our full range of DNA tests available from our award-winning laboratory.