WOMEN WHO USE frozen embryos in IVF treatment may have healthier babies than those implanted with fresh embryos.
New research by Dr Abha Maheshwari, senior lecturer at the University of Aberdeen, suggests that using stored embryos reduced the risk of bleeding in pregnancy by a third and reduced the risk of premature births by 16 per cent.
The risk of giving birth to an underweight baby was half compared with babies born from fresh embryos.
The Guardian reports that the findings, which appear in the journal of Fertility and Sterility, covered more than 37,000 pregnancies in women who had either fresh or previously frozen IVF embryos implanted in their wombs.
Senior clinical embryologist and the director of ReproMed, a fertility clinic at Beacon Court in Dublin, Mr Declan Keane told TheJournal.ie “this is a welcome piece of news supporting proposals put forward over the last five years that perhaps the ‘synthetic state’ of the uterine lining is not optimum immediately after egg harvesting during an IVF cycle.”
The crux of IVF treatment is the very large doses of Follicle Stimulating Hormone (FSH) used to over stimulate the natural growth pattern of the available egg follicles can perhaps cause an over stimulation of the womb lining (in a round about way). This may, in theory, reduce implantation potential of embryos transferred into the same uterine environment.
Mr Keane said that in contemporary Irish IVF clinics the ovarian stimulation programmes are aimed at getting as many available eggs as possible while maintaining patient safety at all times.
“But inherent in ovarian hyper stimulation is that as the quantity goes up, perhaps the quality goes down,” he said adding that the research is basically stating that the embryos created using IVF and ovarian stimulation have a better chance of implantation and survival in the uterus after freezing, but this is suggested to be true not due to freezing, but due to the uterus having time to recover and settle down after the ovarian stimulation.
Mr Keane said:
We know that IVF pregnancy rates are at present lower using frozen embryos rather than freshly created embryos. This is due to the negative effects of the actual freezing process can have on the embryos ‘shell’ and the internal structure of the embryo.
As modern freezing techniques are evolving, these deleterious effects are being countered or avoided and embryo survival rates and implantation are being increased.
Thus in the future embryo freezing and waiting for a better conditioned womb lining months after IVF ovarian stimulation, may be the way forward.
However at present most fertility clinics will work with fresh over frozen embryos.
ITV reports that Dr Maheshwari acknowledges that her research has a number of limitations to it. The research does not look at pregnancy rates, for example.
She said that more clinical trials needed to be conducted and that “in the meantime my advice to women undergoing IVF is that there is no reason, yet, to change the way they approach IVF”.