With Heartiste's recent post entitled "Childlessness And Mass Female Hysteria" as an impetus, the percentage of childless middle-aged women in the US, by decade (n = 13,549):
The female labor force participation ratcheted up beginning in the mid-seventies before peaking around 2000 and steadily but modestly declining since then in line with the overall decrease in labor force participation. During that time, the percentage of childless middle-aged women more than doubled and has continued to inch upward since then. We've gone from fewer than 1-in-12 middle-aged women being childless to nearly 1-in-5 being so.
GSS variables used: SEX(2), AGE(30-50), CHILDS, YEAR(1970-1979,1980-1989,1990-1999,2000-2009,2010-2014)