A liquid absorbent pad includes an elastically stretchable basic sheet upon which an absorbent core is periodically bonded. The absorbent core is bonded while the basic sheet is stretched. The absorbent core includes a structure which encourages the formation of corrugations therein when the basic sheet is released. The corrugations enable the flow of material in the troughs of the corrugations, and thereby reduce soilage of the upper surface of the absorbent core by fetal matter. The liquid absorbent pad is suitable for undergarment use in which the basic sheet includes a waist opening and a pair of leg openings. In one embodiment, the structure which encourages the formation of corrugations includes gaps between adjacent strips of absorbent material. In another embodiment, the structure is periodic regions of reduced density or rigidity. In a further embodiment, the structure includes periodic longitudinal indentations alternating on opposite sides of the absorbent pad.