Tall
Women More Likely to Have Twins
By LiveScience Staff
A
researcher who specializes in multiple-birth pregnancies
has confirmed that taller women are more likely
to have twins.
Taller women have more of an insulin-like growth
factor that has been linked to height and to the
rate of twins in previous work. Dr. Gary Steinman,
an obstetrician at Long Island Jewish Medical Center,
compared heights of 125 women who had twins and
24 who had triplets to the average height of U.S.
women.
Those who birthed two or more children were on average
more than an inch taller.
The study was published in the September issue of
the Journal of Reproductive Medicine.
Insulin-like growth factor (IGF) is a protein released
by the liver in response to growth hormones. It
increases the sensitivity of the ovaries to follicle
stimulating hormone, thereby increasing ovulation.
"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," said Dr. Steinman.
IGF also stimulates cells in the shaft of long bones
to grow. Previous studies have found shorter people
have lower levels of IGF. Other studies suggest
IGF might help
embryos
survive in the early stages of development.
Countries with taller women have higher rates of
twinning, according to a statement released by Steinman.
In a previous
study, Steinman found that women who
consume animal products, specifically dairy, are
five times more likely to have twins. Cows, like
humans, produce IGF in response to growth hormone
and release it into the blood, and the IGF makes
its way into their milk.
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