The Birth Rate for Twins

The Birth Rate for Twins


The birth rate for twins increased by 76% between 1980-and 2009.


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The number of twin births has increased dramatically over the past years. A recent government study showed that the twin birth rate rose 76% from 1980-to 2009! In 1980, one in every 53 babies born in the US was a twin. In 2009, one in every 30 babies was a twin! This increase is due to the tendency for women to delay having children until they are older and the increased use of fertility treatments. Both of these factors increase fraternal (dizygotic or DZ) twins. DZ twins occur when two eggs are released at the same time and are fertilized by two different sperm.

The older a woman is, the higher her chance of having DZ twins. This may be due to the higher level of follicle-stimulating hormone (FSH) that older women have as they approach menopause. FSH stimulates ovulation, and an increased level may cause multiple eggs to be released. So while older women are statistically less likely to get pregnant, they are more likely to have DZ twins if they do get pregnant.

Older women are more likely to have trouble conceiving. And fertility problems are common among couples of any age. The use of fertility treatments has soared since 1980, which has caused a huge increase in DZ twinning. Fertility treatments include fertility drugs and assisted reproductive technologies.


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