A well-fitting diaper is crucial for preventing unpleasant leaks and messes -- and for keeping baby happy. Because diaper sizes correlate mainly to a baby’s weight, this will be your main indicator of the timetable for going up a size in your baby’s diaper. If you miss the mark and keep baby in a too-small diaper, you will likely discover this error in an unpleasant way.
Weigh your baby to learn her weight. If you don’t own a baby scale, take your baby to the doctor’s office to have her weighed. Another option involves weighing yourself, weighing you and your baby together, and then subtracting your weight to calculate your baby’s weight, advises the Pampers website.
Check the weight range for the diapers you are currently using. The weight ranges tend to overlap for the different sizes to allow for variances in a baby’s build. For example, one size diaper may go up to 24 pounds and the next size up may begin at 22 pounds.
Compare your baby’s weight to the weight range for your current size and the next size up to see where it falls. If your baby’s weight falls squarely within a range -- not in the overlap range -- it’s likely that your baby has a little growing room left in his current diaper size. If your baby’s weight falls within the overlap range, assess the fit to see whether you should move up a size.
Examine a diaper in the current diaper size to see how it fits your baby. If you notice red marks around your baby’s upper legs and tummy from the elastic in the diaper, the diaper is likely too small. Additionally, if you notice that the diaper looks or feels too snug on your baby, it is likely too small. You may also begin to notice leaky messes if your baby’s current diaper size is too small, according to the Huggies website.
Try the next size up in diapers to see if it absorbs better and fits your baby more comfortably. If leaks stop and the diaper looks like a better fit, your baby was most likely ready to move up. If you notice excessive gapping at the legs and waist, the diaper may be too large for your baby. Let your baby gain another pound or two and then try again.