DIFFERENT fertility treatments affect the ratio of boy babies to girls, and this could have serious consequences as artificial fertility treatment becomes more common.
So says Michael Chapman at the University of New South Wales in Sydney, Australia, following a study that compared different kinds of assisted fertility treatment (AFT). His team recorded the sex of all 13,368 babies born in Australia and New Zealand between 2002 and 2006 using AFT.
They compared two types of reproductive technology: IVF, which involves placing an egg on a dish with up to 1000 sperm, and intracytoplasmic sperm injection (ICSI), in which sperm are injected directly into the egg - an approach used for low-quality, immotile sperm. They also compared the stage an embryo was at when transferred to the womb.
IVF raised the proportion of boys to 53 per cent, while with ICSI it fell to 50 per cent. The natural proportion of boys is 51.5 per cent.
The stage at which the embryo was transferred had the greatest effect. The later the transfer, the more likely it would result in a boy (British Journal of Obstetrics and Gynaecology, DOI: 10.1111/j.1471-0528.2010.02731.x).
Chapman suspects the culture medium that is used to grow the embryo is affecting the baby's sex. He is working with clinics to record the type of formula used in the study period.
So says Michael Chapman at the University of New South Wales in Sydney, Australia, following a study that compared different kinds of assisted fertility treatment (AFT). His team recorded the sex of all 13,368 babies born in Australia and New Zealand between 2002 and 2006 using AFT.
They compared two types of reproductive technology: IVF, which involves placing an egg on a dish with up to 1000 sperm, and intracytoplasmic sperm injection (ICSI), in which sperm are injected directly into the egg - an approach used for low-quality, immotile sperm. They also compared the stage an embryo was at when transferred to the womb.
IVF raised the proportion of boys to 53 per cent, while with ICSI it fell to 50 per cent. The natural proportion of boys is 51.5 per cent.
The stage at which the embryo was transferred had the greatest effect. The later the transfer, the more likely it would result in a boy (British Journal of Obstetrics and Gynaecology, DOI: 10.1111/j.1471-0528.2010.02731.x).
Chapman suspects the culture medium that is used to grow the embryo is affecting the baby's sex. He is working with clinics to record the type of formula used in the study period.
**Published in "New Scientist"
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