Compound sanitary napkin having flaps and zone of extensibility

The present invention relates to a compound sanitary napkin (20) comprising a primary absorbent member (30), a base member (50), flaps (33) and at least one zone of extensibility (66). The compound sanitary napkin (20) has a longitudinal center line along a longitudinal direction and a transverse center line along a transverse direction. The primary absorbent member (30) has a longitudinal length (PL), a transverse width (PW), a thickness (PT), a pair of longitudinal sides (24) and a pair of transverse ends (25), and comprises a primary absorbent element (30) and a fluid pervious cover (32) superimposed on the primary absorbent element (30). The base member (50) has a longitudinal length, a transverse width, a thickness, a pair of longitudinal sides (21) and a pair of transverse ends, and comprises a fluid pervious body-facing sheet (52) and a fluid impervious garment-facing sheet (54) joined to the fluid pervious body-facing sheet (52), the primary absorbent member (30) is joined to the base member (50) at least at a part of the longitudinal direction of the primary absorbent member (30). Flaps (33) extend laterally outwardly from the longitudinal sides of the base member (50). Each of the flaps (33) has a proximal edge (40) joined with the longitudinal sides (21) of the base member (50), a distal edge (41) spaced laterally outwardly from the proximal edge (40). The flaps (33) cover a portion of the leg openings of the wearer's undergarment. At least one zone of extensibility (66) comprises at least a portion of the flaps (33), wherein at least a portion of the zone of extensibility (66) is spaced longitudinally away from the flap transverse centerline. The entire length of the proximal edge of the flaps (33) is not less than 20% of the length of the primary absorbent member (30). At least the zone of extensibility (66) is extensible to be capable of a stress given to the flap (33) when the compound sanitary napkin (20) is worn so that the flaps (33) are relatively free from shifting when at least a portion of the primary absorbent member (30) shifts away from the flap (