from journal Nature Communications
Previous studies have suggested that women who have twins are simply more fertile. A new study challenges that theory—reasoning that if the women were more fertile, they would give birth more often. An international team of researchers re-examined the relationship between twinning and fertility in more than one hundred thousand births dating back to pre-industrialized Europe. Results, published in the journal Nature Communications, suggests twinning has not been eliminated by natural selection because it is a result of double ovulation which benefits all but the youngest of mothers. Their conclusion is that mothers of twins are not more fertile, just lucky.