Fertility and pregnancy * Babies and children

IVF increases the chances of a baby boy

IVF increases the chances of a baby boy ICSI lowers it

Certain types of fertility treatment may increase a woman's chances of giving birth to a boy, say experts.

Researchers from the University of New South Wales looked at all live births following fertility treatment in clinics in Australia and New Zealand between 2002 and 2006, during which time nearly 14,000 babies were born.

They compared the ratios of male to female babies born by the standard IVF method or by intracytoplasmic sperm injection (ICSI). During ICSI, the male sperm is injected directly into the woman's eggs.

With fertility treatment, the chances of a boy being born was 51.3 per cent, similar with boys conceived naturally in the Australian population. However, this figure dropped to 50 per cent when ICSI was used and rose to 53 per cent when women became pregnant using IVF.

The male to female ratio was also different depending on what stage the embryo was transferred back into to the woman, with 49.9 per cent male babies born from embryos transferred after two days, and 54.1 per cent at five days.

The chances of having a baby boy was highest (56 per cent) when IVF was used, and the embryo transferred after five days.

The findings are published in the British Journal of Obstetrics and Gynaecology (BJOG).

Jishan Dean, study co-author at the Reproductive and Perinatal Epidemiology Research Unit, said the findings should not be used as a tool for "sex selection."

Professor Philip Steer, BJOG editor-in-chief said: “In the general population, the secondary sex ratio has been shown to vary over time and according to external factors such as in times of hardship, e.g. famine or war.

"This could be nature’s way of balancing the sexes, ensuring the survival of the human species. It is important that we don’t allow such imbalances to occur unintentionally, simply because we have neglected to study the factors that influence the secondary sex ratio in the increasing proportion of the population who use assisted reproductive technology.”

This article was published on Wed 29 September 2010

Image © Jamey Ekins - Fotolia.com

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