Sometimes the number of young twins I notice seems remarkable compared to the relative rarity of twins I knew from my own childhood. Double, and even triple, buggies seem to be everywhere. Both of my children have twin friends, and know a few others. Twins do run in families, usually a genetic predisposition from the mother's side. They are also more likely to occur in women of African descent. However, there are two additional reasons for the increase in twin births in the past 2 decades:
- First, women have been having children later than in previous generations. Twins occur more frequently as the mother's age rises at the conception of her children.
- Secondly, the increase in IVF and the implanting of more than one embryo per cycle has resulted in more twin births.
However, news reports this week have revealed that twin births are declining in the UK now.
You may wonder what difference it makes if women are having twins rather than single births. After all, it still has the novelty factor. Some parents may prefer to have twins and not go through a second pregnancy and birth experience, especially if it would involve another round of IVF. For convenience and cost, it might make sense. However, there are several disadvantages to multiple births that should be considered.
The Human Fertilisation and Embryology Authority (HFEA) considers multiple births the "single biggest risk of fertility treatment." The increased risks of multiple births, according to the HFEA, include:
- miscarriage and other pregnancy complications
- premature and/or low birth weight
- neonatal mortality: 19/1,000 deaths within the first month of life for multiple babies, compared to 3/1,000 live births for single babies
- cerebral palsy: HFEA quote 6.2/1,000 live births for twins compared to 1.7/1,000 live births for single babies
- of newborns requiring special neonatal care
- maternal pregnancy-induced high blood pressure (hypertension), pre-eclampsia, pregnancy diabetes, assisted or interventional delivery (e.g., a caesarean), and mortality.
Its aim has been to reduce that risk by encouraging the transfer of single, rather than multiple, embryos per cycle. The program is having a swift and definitive impact on the trend of multiple births. The first target level set in 2009/2010, required that fertility clinics have a rate of no more than 24% multiple births from assisted reproduction techniques. For 2010/2011, the target was lowered to 20%, and in April 2011 the target has been set to 15%, which UK clinics are expected to meet by this time next year. The ultimate aim is a multiple birth rate of no more than 10% each year.
So, what does this mean for you if you are currently trying to conceive? If you are having fertility treatment in the UK, are under the age of 35 and considered to have a high chance of successful conception, you may find your clinic unwilling to transfer multiple embryos. Up to the age of 40, the HFEA restricts transfer to 2 embryos. From age 40, the group which is least assured of success with IVF, a woman may elect to have up to 3 embryos transferred. Any additional embryos created in vitro can be frozen and used later.
If you require more information about elective Single Embryo Transfer (eSET), a good source of information is the One at a Time website, which is dedicated to "better outcomes from fertility treatment." The site includes information about the guidelines, best practice, the risks of multiple pregnancies and what is involved in carrying, giving birth to and raising twins and triplets.
Additional sources:
Women who carry more than one child have a greater risk of miscarriage and medical complications, including anaemia, haemorrhages and high blood pressure. The babies are also at risk of serious health problems, with twins four times more likely to be born with cerebral palsy than a single baby.
Posted by: Increase Fertility | November 16, 2011 at 07:45 AM