Answer :

After the  passing of the 19th amendment, legislators feared the creation of a powerful female interest group. Out of this fear, acts like the Shepard-Towner Act (1921) which  provided federal funding for maternity care were passed. 
A curious fact, about the 19th amendment is that granted voting rights to white and black women. Nevertheless, within a decade black Southern women were back to disenfranchisement. Such granting and then stripping of power might have provided steam to the Civil Rights Movement of the 1960s.