With more and more couples opting for in vitro fertilisation as the rate of infertility rises globally, scientists soon realised that they needed to study the whole process of in vitro fertilisation more thoroughly and discover its effect on embryonic growth. A team of scientists from Helsinki University decided to do just that. This new study done by the University of Helsinki, Helsinki University Hospital and University of Tartu shows that the process of IVF does have a significant effect on embryonic growth. The study suggests that IVF mainly affects the size of the newborn. Children born with the help of the IVF technique- where a fresh embryo transfer technique, have a smaller birth weight than compared from those who were born with the help of frozen embryo transfer. Apparently babies developed from the frozen embryo transfer weigh a bit more than the average. The aim of the study was to properly understand the mechanisms of in vitro fertilisation so as to develop the technology further in the future. Nina Kaminen-Ahola, leader of the research team at the University of Helsinki said, “Low birth weight has been associated with increased risk for heart and vascular diseases and therefore it is necessary to understand the mechanisms underlying it to develop the IVF methods”. In the future, this could be a part of personalized medicine and help to target the sources of health care system more specifically.”
For the study the team studied 86 couples with IVF derived pregnancies and 157 couples with spontaneous pregnancies. The IVF specimens were then divided into two categories- on the basis of whether the embryos were transferred in the uterus fresh just after the fertilisation or that they were transferred after the embryo was frozen and then thawed for the transfer. For results the team kept their focus on the regulation regions of two growth genes- insulin-like growth factor 2 and H19. A common genetic variation in these two growth regulation regions has been linked to different amount of epigenetic marks depending on what characters or variants the embryo had inherited from the parents. Researchers observed DNA-methylation which is said to be one of the best known epigenetic mark because the methyl group combines with the DNA strand and influences the functions it’s supposed to perform. Kaminen-Ahola explains, “We divided the placentas in genotypes according to the variants which the newborns had inherited, and we observed that the effect of IVF on the epigenetic marks depends on the genotype.”
The results were a bit surprising to say the least. The birth weight, placental weight and the circumference of the head of the newborns that were born with the help of fresh embryo transfer technique were smaller but only in one distinct genotype. Babies that were conceived with the help of the frozen embryo transfer technique weighed significantly more. The results of the research and the research itself is quite interesting, as it tries to associate genetic factors with the phenotype of the newborns born by IVF. Kaminen-Ahola further explains, “This single nucleotide polymorphism locates in the binding site of a regulatory protein, and thus could affect the binding of the protein as well as gene function in altered environmental conditions. However, the effect of this variation on the regulation of these growth genes should be examined by functional studies.”