Baby clothing sizes are usually based on age: preemie, 0 to 3 months (newborn), 3 to 6 months, 6 to 9 months, 9 to 12 months, 12 months, 18 months, and 24 months.

Others may even grow out of 3-month-old size clothes after only 1 month. So, buy items in the 6-month or 1-year size to have on hand. Twins tend to be smaller than single babies, so the tiniest ...

Available in sizes newborn through 18-24 months, this ultra-soft ribbed organic cotton bodysuit includes three sets of snaps so you can keep your baby comfy as they continue to grow.