Whether you give birth to a boy or a girl is finally in your hands.
According to researches, women aspiring to have baby boys should tuck into burgers, fries and ice cream, while those who want a girl should go on a diet and lose some weight.
It works for cows, according to John Roche, a scientist at New Zealand's dairy research organisation Dexcel. "And we would expect that what holds true for one mammal will hold true across the board," he said.
Dexcel and Ireland's Teagasc agricultural organisation studied 1,200 cows in an 18-year research project from 1986 to 2004.
They found that cows that gained weight before conceiving were more likely to give birth to bull calves. Those shedding kilos before conception had a better chance of producing heifers (females).
Roche told the Waikato Times, published in Hamilton, that the research underlined the theory that humans had some control over the sex of their children.
"Many theories have been put forward," he said, citing weather patterns, phases of the moon, bathing rituals and the timing of mating, etc.
"However, there has been little consistent scientific evidence till now."
Roche said that it was not clear exactly why weight affected the sex of a cow's offspring.
Although the male determined the sex of the embryo at conception, the female had some control over whether to keep a male or a female one.