IVF-lings are a group of children who share the common characteristic of having been conceived using IVF. Naturally enough, both parents and IVF-lings are curious to know if there is anything ‘different’ about them.
In New Zealand the oldest IVF-ling conceived here is still only 25 years old, the group of IVF-lings is still small (but growing), and parents may not have been keen for their children to be part of a research group – this means that research about IVF-lings can be a little thin on the ground. Research about IVF-lings continues to progress with lots of new and interesting studies - some controversial!
Check out some information based on generally accepted research here…
A congenital abnormality is a problem that a baby is born with. There are different types of congenital abnormality with different cause. The chance of congenital abnormalities in children born after IVF or ICSI is about a third higher than for children conceived naturally, which means a chance of around 4 per 100 births instead of 3 per 100 births. It is still not clear whether this increase is due to the IVF procedure or related to the parents’ infertility.
There might be a slightly higher rate of abnormalities caused by chromosomal issues in IVF-lings who were conceived using ICSI.
The chance of abnormalities such as Down Syndrome is the same in IVF and ICSI pregnancies as in the general population, which shows a sharp rise with age, especially after the mid-30’s and many women having IVF are 35 years or older.
Recent studies suggest IVF and ICSI are probably associated with a higher risk of various rare disorders associated with the ‘imprinting’ of genes. Imprinting disorders such as Prader-Willi Syndrome and Angelman Syndrome occur in about in 1: 10,000 children conceived naturally; with IVF and ICSI the rate probably increases to about 1:2,000.
If some of the embryo’s cells are damaged during freezing and thawing, the chance of that embryo implanting and giving rise to a child is lower than if the embryo does not sustain any damage, but there is no greater risk of abnormalities. At this early stage of embryo development, each cell of the embryo is capable of giving rise to an individual person.
Phase 1 - Fresh embryo research
There have been several large follow-up studies from the USA and various European countries that altogether included several thousand children, mainly up to the age of 10. Physical, mental, and social development of IVF
children was similar to children conceived naturally.
Recently, scientists and doctors have become interested in the possibility of more subtle differences. One of the earlier and better designed studies was conducted for Fertility Associates and the Liggins Institute by Dr Harriet Miles. This corrected children’s height for how tall their parents were, and measured a range of hormones, body fat, and blood lipids like cholesterol. IVF children born from the transfer of fresh embryos were taller than controls (non-IVF children), especially the girls. The IVF children also had higher levels of some growth factors called IGFI, IGFII and IGFBP3, as you would expect from them being taller. They also had more favourable lipid profiles.
Phase 2 - Thawed embryo research
A second study by Dr Fan Mouat at the Liggins Institute looked at children born from using frozen-thawed embryos. These children were not quite as tall as those from using fresh embryos. On average, one growth factor (IGFII) was higher and another factor (IGFBP3) was lower in these children compared to controls, which also ties in with them not being quite so tall.
The reasons for these differences are unknown. One possibility is that the IVF process might subtly change the expression of some genes associated with growth and height. These sorts of changes are called ‘epigenetics’, which is ‘hot’ area of study at present. Another possible reason is that usually the faster developing embryos are selected for ‘fresh transfer’, while other good quality embryos are frozen for later use. If this was the explanation, the results would be due to the selection of embryos and not to any effect of IVF on the embryos.
A study of over 5000 children conceived after IVF showed a similar rate of childhood cancers to children conceived naturally.