Abstract: The invention relates to extensible maternity slacks having a front flap adapted to be joined to the edge of a rear flap by a button-hole co-operating with a plurality of buttons, the front flap further comprising on its upper edge a waist-band containing a reinforcing elastic which comprises, in known manner, a succession of regularly spaced apart median button-holes, so that one of the button-holes, located at the side edges, is adapted to co-operate with a button located on the side of the said front flap, substantially where the said waist-band opens out, the judicious choice of the button-hole, fitted on the button, enabling the tension of said flap to be adjusted at its upper edge.