Combination bathtub and infant-supporting insert are provided with interengagable members for firmly holding the insert in any of multiple inclined positions, enabling support of an infant on its back from a near horizontal position shortly after birth to a near-upright position at the stage that it is almost ready to outgrow the tub. The tub and insert are each preferably injection molded as a single piece from an appropriate plastic material. The infant-supporting surface is smoothly contoured to properly support the back, head and bottom of the infant in all angles of inclination, regardless of the infant's size.