Hormone may be behind twins surge

Older women are more likely to conceive twins because rising concentrations of a naturally occurring hormone overstimulate their ovaries, researchers have found.

The discovery by a team of scientists from Amsterdam’s Vrije Universiteit, revealed in the Feb. 23 edition of the journal Human Reproduction, solves a riddle that has been perplexing the medical profession for years.

“The findings give credence to previous theories that the rising concentrations of follicle-stimulating hormone (FSH) that occur as women age can cause some ovaries to go into overdrive, tripping them into a state where they have simultaneous double ovulation,” they said.

One of the researchers, Cornelius Lambalk, said the discovery helped explain why there was a surge in the number of non-identical twins born to older women at the same time as their general state of fertility was declining because of age.