Your baby grows quickly, moving through several sizes of disposable diapers in just the first year. Knowing when a diaper is starting to get too small is important to avoid messes, to keep your baby comfortable and to help you select the proper size when you purchase your next package of diapers. A visual inspection of your baby's diaper and bottom can help provide you with the information you need to make a knowledgeable decision about when to move to the next size diaper.
Test the elastic around your baby's legs. Place your finger between your baby's leg and the diaper. Lift slightly to see if the elastic has any "give." If it does not, the diaper is too small. A second way to test is to open your baby's diaper. Look at the area around their legs where the diaper fits. If the area is red, the diaper is too tight.
Close the tabs on the front of the diaper and notice if they close easily or if you have to pull the tabs to get them to close. If you have to pull the tabs to get them closed, the diaper is too small.
Look at the waistline of the diaper where you connect the tabs. The waistline, or top of the diaper, should end approximately 1 inch below your baby's belly button. If the waistline is more than 2 inches below your baby's belly button, your diaper is too small.
Look at the fit of your baby's diaper. A proper-fitting diaper will be loose throughout the main body and snug around the waist and legs. If the diaper conforms and fits snugly against your baby's bottom, the diaper is too small.
Watch for frequent leaks and blowouts. If the diaper is too small, you will start to notice more frequent leaks and possibly diaper blowouts, or explosions, because the diaper doesn't fit properly and can no longer contain what your baby eliminates.
Redness around the elastic on your baby's diaper may not mean the diaper is too small. If the elastic around the legs has give and the tabs of the diaper align close to your baby's belly button, then there's a possibility that the redness is an allergic reaction to the diaper. Check with your doctor to be sure.