From the press release:
Two-thirds of women who had their first child between 2001 and 2003 worked during their pregnancy compared with just 44 percent who gave birth for the first time between 1961 and 1965, according to a report released today by the U.S. Census Bureau.
The report, Maternity Leave and Employment Patterns: 1961-2003, analyzes trends in women’s work experience before their first child, identifies their maternity leave arrangements before and after the birth and examines how rapidly they returned to work.
Women are more likely to work while pregnant than they were in the 1960s, and they are working later into their pregnancies. Eighty percent who worked while pregnant from 2001 to 2003 worked one month or less before their child’s birth compared with 35 percent who did so in 1961-1965.