More than two-thirds of early miscarriages appear to be caused by abnormalities in the chromosomes, the packages of DNA in every cell of an embryo or fetus. The remaining third is also probably due to genetic factors and may not yet be detected.
It was previously thought that about half of miscarriages were caused by these chromosomal abnormalities. Now, new technology has revealed that the majority of early miscarriages are, in fact,:
Source: www.newscientist.com