The claim: Morning sickness means a woman's more likely to have a girl.
The facts: Old wives' tales about predicting a baby's sex - relying on clues like the way the woman carries and the foetal heart rate - are usually more fantasy than fact.
However, the notion that morning sickness can sometimes indicate that a girl is on the way may be an exception. A large number of studies in various countries have examined the claim and almost all have found it to be true, with caveats.
Specifically, studies have found that it applies to women with morning sickness in the first trimester and with symptoms so severe that it leads to hospitalisation. It's a condition known as hyperemesis gravidarum.
One of the most recent studies was conducted by epidemiologists at the University of Washington. The scientists compared 2,110 pregnant women who were hospitalised with morning sickness in their first trimester and a control group of 9,783 women who did not get severely ill.
They found that the women in the first group were more likely to deliver a girl and that those who were the most sick - hospitalised for three days or more - had the greatest odds: an increase of 80 per cent compared to the women in the control group.
Other studies in The Lancet and the journal Epidemiology, among others, have repeated the findings. It is thought that certain hormones produced by female foetuses may be the culprit.
The bottom line: Severe morning sickness may indicate a higher likelihood that the baby will be a girl.
This story was first published in Mind Your Body, The Straits Times, on Aug 28, 2008.
