A recent large study from Australia found that women undergoing IVF were at significantly higher risk of having a severely underweight or stillborn baby or one born prematurely or which dies within a few weeks of birth compared with women who conceived naturally.
The effects were also found although to a lesser extent in ICSI cycles. Overall there was a 2 to 5 fold increase in these complications in babies conceived following IVF. Some of these facts were already known from other studies but what was revelatory was that conceptions following implantation of a frozen embryo had a much reduced incidence of complications. For example a baby born after IVF was over half a pound lighter than a spontaneously conceived baby but this did not apply in those babies born after frozen embryo transfer. The authors of the paper postulate that implantation of the embryo transferred in a fresh stimulated IVF cycle can be compromised by high levels of oestrogens resulting from the use of stimulating drugs used to boost the number of eggs which does not occur when a frozen embryo is subsequently transferred in an unstimulated or natural cycle. So now we have proof that avoidance of high oestrogen levels which is common in conventional stimulated IVF cycles will not only reduce health risks for the mother but for the baby as well. As someone who has championed mild and natural IVF for many years I feel vindicated by these findings. The association of frozen embryo transfer cycles and better outcome has been reported before this and has prompted discussion as to whether freezing all embryos for later transfer should become routine if conventional stimulation is used. This is however is an expensive and unnecessary option. The logical way to reduce the health risks for mothers and babies associated with high oestrogen levels in IVF is the adoption of mild and more natural IVF protocols. Babies born following modified natural cycle IVF have been shown to be heavier than those born from conventional IVF which fits in with the findings of this study that unstimulated endometrium is healthier for the growth of babies. Furthermore maternal complications such as ovarian hyperstimulation syndrome can be avoided in mild IVF cycles. Conventional IVF is still the common form of IVF practised in the UK but following this study, it will be increasingly difficult to justify transfer of fresh embryos in cycles with high oestrogen levels.
Two unexplained findings from the study are worthy of comment. Women who conceived following a period of infertility but who were never treated had a higher risk of unfavourable pregnancy outcomes but the authors could not confirm whether the women were self-medicating with fertility drugs or were having therapies through specialist clinics which might have influenced the outcomes.
Finally, there is one further important lesson from this study. The Australian team were able to link the data from women having IVF treatment to their pregnancy and delivery database, which allowed the correlation of treatment and outcome to be obtained. In the UK almost 50,000 IVF cycles are carried out each year but no reliable outcome data is obtained because there is no linkage of the IVF database to the UK perinatal database. This must be addressed as a matter of urgency.