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Tuesday, 29 January, 2002, 23:55 GMT
Hormones give baby sex hint
Male and female pregnancies produce different hormone levels
Doctors say that a hormone in the blood during the first days of pregnancy could suggest whether a boy or girl is on the way.

However, they say much more work needs to be done before mums-to-be could reliably learn the future sex of their children this way.

Currently, an ultrasound examination at 11 to 12 weeks is the earliest point at which any clue is available - in skilled hands, the scan can tell the sex with 75% to 80% accuracy.

However, researchers at the Prenatal Genetic Diagnosis Unit at Tel Aviv Medical Center in Israel found that only 16 days after conception, clear differences in the levels of the hormone - called HCG - could be detected between mothers carrying male and female foetuses.

Home pregnancy testers

Girl foetuses have on average a fifth higher level of the hormone.

HCG is already known to be a reliable indicator of pregnancy itself - home pregnancy tests detect raised levels.

And, doctors can also use it , either alone or in combination with other tests, to detect dangerous ectopic pregnancies, or Down's syndrome pregnancies.

The Israeli study, published in the journal Human Reproduction on Wednesday, looked at 347 IVF pregnancies, with the women tested for HCG levels between one and three times from day 14 to day 20.

There were 184 girl foetuses and 163 boys - and hormone levels were 18.5% higher by three weeks gestation in pregnancies.

More evidence needed

However, the team conceded that, on its own, this would be unlikely to be reliable enough to confidently predict sex just a few days after conception.

It would not be accurate enough to use on its own - there would have to be more markers before a test could happen

Dr Kevin Spencer, Harold Wood Hospital
Dr Yuval Yaron, who led the research, said: "Although the gender differences are statistically significant, the proportion of pregnant women with HCG concentrations high or low enough to allow a prediction with high probability is too small.

"It would be possible to predict the sex of a foetus is we can identify other markers that also demonstrate early gender-related differences.

"We are working on this now and hope to have some results soon."

British expert Dr Kevin Spencer from Harold Wood Hospital in Essex uses HCG testing as part of a non-invasive Down's screening programme.

He agreed that checking the levels of this hormone in isolation would be too unreliable to offer as a sex test.

He told BBC News Online: "It would not be accurate enough to use on its own - there would have to be more markers before a test could happen."

See also:

03 Jan 01 | Health
Womb injections save baby
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