Some IVF techniques leading to more bundles in blue: Study

By Dr. Ananya Mandal, MDSep 29 2010

According to a new study by Australian researchers some infertility treatments may influence the sex of a baby to such an extent that increased uptake could upset the gender balance later. The study shows that a type of IVF treatment increases the chance of having a boy to as much as 56.1 per cent, while another treatment cuts it to 48.7 per cent.

The difference according to the researchers from University of NSW was too small to be useful for individual couples as a means of sex selection that is illegal in Australia, but it could create problems if reflected across populations. The study appeared in the international obstetrics journal BJOG and it looked at all 13,368 babies born through single-embryo-transfer procedures in Australia and New Zealand between 2002 and 2006.

Authors report that there are two variables that could affect the sex of the baby. One was the type of IVF procedure, and the length of time the fertilised egg was left to develop before being transplanted into the mother's womb. For commonly used procedures in which the egg and sperm were allowed to combine by themselves, there was an increased rate of male babies by 53 per cent. With alternative treatment like intra-cytoplasmic sperm injection (ICSI), in which the sperm is artificially injected into the egg the chance of having a boy is reduced by 50 per cent. Also if the fertilised egg is independently transferred after two or three days chances of a boy was reduced while delaying transfer for an extra day or two increased it. Authors speculate that these two variables cancelled each other out and thus the rate of male births from all IVF treatments in the study was similar to the normal rate -- 51.3 per cent compared with the natural level of 51.5 per cent.

However the authors also believe that balanced use of the two fertility treatments could not be assumed, and the use of ICSI -- linked to a higher rate of girls -- had already risen in Australia and New Zealand from 57.6 per cent of fertility treatments in 2002 to 59.5 per cent in 2006.

According to lead author Jishan Dean male birth rate of 56.1 per cent meant 127.8 boys would be born for every 100 girls. She said if this was true “you really have a problem, because you will have men who can't find a wife”, a real situation in China.

According to infertility specialist Frank Quinn, clinical director of IVF Australia the study is interesting but the real impact on society is still unclear since IVF treatments accounted for 3.3 per cent of births in Australia.