If you have spotted a bunch of towering women in your neighborhood pushing double strollers, there is a reason: Tall women are more likely to have twins, according to a study in the September issue of the Journal of Reproductive Medicine.
Gary Steinman, an obstetrician at Long Island Jewish Medical Center who specializes in multiple-birth pregnancies, has linked twin births to having higher levels of insulinlike growth factor (IGF), a protein that is released from the liver in response to growth hormone. This protein increases the ovaries’ sensitivity to a hormone called follicle-stimulating hormone, which increases ovulation.
This same protein stimulates the growth of long bones; past studies have shown shorter people have markedly lower levels of the insulinlike growth factor.
In his study, Steinman compared the height of 129 women who gave birth to identical or fraternal twins or triplets with the average height of women in the United States. The mothers who had twins or triplets averaged 5 feet 5 inches tall, more than an inch taller than average.