Taller women more likely to have twins
(Reuter)
Updated: 2006-09-26 10:58 NEW YORK - Taller women are
more likely to have twins, according to a U.S. study.
Gary Steinman, an obstetrician at New York's Long Island Jewish Medical
Center, compared the heights of 129 women who gave birth to twins or triplets
with the average height of women in the United States and found women with
multiple-birth pregnancies averaged more than an inch taller.
Steinman, whose study is being published in the September issue of the
Journal of Reproductive Medicine, said the reason seems to be an insulin-like
growth factor, which has been positively linked to both height and twinning.
Insulin-like growth factor is a protein that is released from the liver in
response to growth hormone. It increases the sensitivity of the ovaries to
follicle stimulating hormone, thereby increasing ovulation, the study said.
"Any circumstance that affects the amount of available insulin-like growth
factor so as to modify the sensitivity of the ovary to follicle-stimulating
hormone appears to govern the rate of spontaneous twinning," Steinman said in a
statement.
Previous studies have demonstrated that shorter people have significantly
lower levels of this protein and that countries with taller women have higher
rates of twinning compared to countries with shorter women.
In a previous study, Steinman found that women who consume animal products,
specifically dairy, were five times more likely to have twins. Cows, like
humans, produce insulin-like growth factor in response to growth hormones and
release it into the blood, and the protein makes its way into their
milk.
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