Vienna, Austria ? More than two-thirds of single women who choose to have a baby using donated sperm do so because they fear they are running out of time to find a man they would want to have a child with, new research indicates.

In the first study to look at solo mothers using sperm banks, researchers found that fertility problems were not the motivation in most cases.

“More than two-thirds of the single women said their decision to have a baby by donor insemination was prompted by a growing sense that time was running out to fulfill the lifelong dream of having a child,” said the study’s lead investigator, Dr. Clare Murray, a researcher at the Family and Child Psychology Research Center at City University in London.

Murray was to present the findings today at the annual meeting of the European Society of Human Reproduction and Embryology in Vienna.

Murray said many of the mothers in the study would have preferred to have a child within a relationship. However, nearly a third of the women, whose average age was 38, said they actively wanted to go it alone.

The issue of whether single heterosexual women should have access to sperm banks has been controversial, and some clinics require women to be in a stable relationship before they will offer artificial insemination.

There has been no scientific research on the long-term emotional health of children born to single mothers from donated sperm.

But Murray’s early results found no difference in the quality of parenting between single and married donor-inseminated mothers. So far, the children in both groups appear to be thriving equally.

The researchers compared 22 single women whose babies were born from donor sperm with 36 married women who had undergone the same treatment.

The babies studied were all less than a year old. The researchers plan to follow the children for many more years.

There were no differences between the two groups of children in eating and sleeping difficulties.

The major concerns in the years to come would be a lack of social support for the solo mothers and possible social stigma, Murray said.