We're so sorry you experienced a leak with Pampers. As parents ourselves, we know that’s frustrating. Our Quality Team assures us that your little one may be happier in a size 4 Pampers Baby Dry, as they may be needing more absorbency than is available in the size 3. Every baby’s shape and size is unique, so knowing the following helps ensure a perfect fit, which will stop leaks before they can happen. The diaper works best when the waist is snug with the diaper just under the belly button. After putting on the diaper, run your finger inside the edge of the legs, making sure the cuffs are pulled out. Cuffs being tucked inside are a common cause of leakage. We’d be happy to talk further with you about this, and help you both stay dry. Call us any Monday through Friday, from 9 AM to 6 PM, EST. Our number is 1 (800) 726-7377.