Many of the women infected with the virus are single parents.
A woman infected with syphilis may pass it along to her newborn.
A 34-year-old woman from Connecticut, also infected with the virus, was one of six to respond.
In this age group, there are 36 women infected with HIV for every 10 men.
"When that's going on, it's not surprising that there's been such an influx of women being infected."
Pregnant women infected for the first time by Toxoplasma may pass it to their unborn children.
The city's study found about the same proportion of women infected as babies who tested positive for the antibodies.
In most populations, the birth rate is around 51% boys, but women infected with T. gondii had up to a 72% chance of a boy.
One of the highest-risk groups is young married women infected by straying husbands.