An infant or adult diaper having a longitudinal centerline and a lateral centerline perpendicular to the longitudinal centerline, wherein the diaper comprises a topsheet and a backsheet and positioned therein between an absorbent core, and a first and second longitudinally extending opposing elastic cuffs (30a, 30b), positioned on either longitudinal side of the topsheet, each of the diaper, topsheet, backsheet, absorbent core and elastic cuffs (30a, 30b) having a crotch region, positioned in between a front region and a back region, wherein the diaper comprises a transverse separator sheet made of a separator sheet material, the transverse separator sheet having a transversely extending top edge and top edge portion and an opposing transversely extending bottom edge and bottom edge portion, and - parts of the top edge portion being attached to the cuffs (30a, 30b) in the crotch regions or front regions of the cuffs (30a, 30b) thereof by means of attaching a first attachment area of the top edge portion to the crotch region or front region of the first cuff and a second opposing attachment area of the top edge portion to the crotch region or front region of the second cuff, to form a first cuff attachment area and a second cuff attachment area, each cuff attachment area (13a, 13b) having an inner edge (131a, 131b) towards the longitudinal centerline of the diaper; and - part(s) or all of the bottom edge portion being attached to the topsheet with at least one topsheet attachment area, whereby the separator sheet's minimum transverse dimension in relaxed state of the separator sheet between the opposing inner edges (131a, 131b) of the first and second cuff attachment areas (13a, 13b) is at least 20 mm and whereby the separator sheet's minimum longitudinal dimension in relaxed state of the separator sheet between the top edge and the bottom edge of the separator sheet is at least 30 mm; and the transverse separator sheet: - has a transverse strain of 0.8 at a first cycle extension force of 1.0N or less, as measured according to the in-use two-cycle hysteresis test; and - has 30% set or less after having been extended to a transverse strain of 0.8, as measured according to the in-use two-cycle hysteresis test; and - is elastically extensible in the transverse direction to a strain of at least 0.8, as measured according to the in-process two-cycle hysteresis test at 22°C. - parts of the top edge portion being attached to the cuffs (30a, 30b) in the crotch regions or front regions of the cuffs (30a, 30b) thereof by means of attaching a first attachment area of the top edge portion to the crotch region or front region of the first cuff and a second opposing attachment area of the top edge portion to the crotch region or front region of the second cuff, to form a first cuff attachment area and a second cuff attachment area, each cuff attachment area (13a, 13b) having an inner edge (131a, 131b) towards the longitudinal centerline of the diaper; and - part(s) or all of the bottom edge portion being attached to the topsheet with at least one topsheet attachment area, - has a transverse strain of 0.8 at a first cycle extension force of 1.0N or less, as measured according to the in-use two-cycle hysteresis test; and - has 30% set or less after having been extended to a transverse strain of 0.8, as measured according to the in-use two-cycle hysteresis test; and - is elastically extensible in the transverse direction to a strain of at least 0.8, as measured according to the in-process two-cycle hysteresis test at 22°C.