You should have seen a demonstration bathing in the maternity hospital. Remember to fill bath with water to a depth of 4 inches (10cm), no deeper & check the temperature (water must be at blood-heat temperature). Test the water with your elbow, if it is comfortable, the temperature is correct. Now proceed by undressing baby.
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holding baby with both hands, lower into bath, always supporting the head
baby skin is delicate, so don't use bubble bath, only baby soap & lotion