Over the past 110 years, 705 441 girls and 593 boys have been named Cynthia. The name Cynthia ranks 33th in the United States among the most common names for girls. For the first time more than ten times newborns were named Cynthia in 1910. The peak of popularity of the name Cynthia came in the 1950s and 1960s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.