If you're traveling with a lap infant, you can bring aboard a diaper bag in addition to a permitted carry-on and personal item. They also consider breast pumps as assistive devices and do not count them as a carry-on bag.

On most full-service airlines in 2026 (such as American, Delta, and United), a diaper bag is not counted toward your standard carry-on or personal item allowance. These airlines typically allow parents traveling with an infant to bring one diaper bag per child as a "bonus" item at no extra cost. This is because they recognize that baby essentials like milk, wipes, and snacks are medically and logistically necessary for the flight. However, on "Ultra-Low-Cost Carriers" (ULCCs) like Spirit, Frontier, or Ryanair, the rules are much stricter; on these airlines, a diaper bag often does count as your one allowed personal item. If you bring both a backpack and a diaper bag on a budget carrier, you may be charged a gate-check fee. For all airlines, the diaper bag must still fit within standard "personal item" dimensions (roughly 18 x 14 x 8 inches) to ensure it can be stowed under the seat in front of you. Always check your specific 2026 fare rules, as "Basic Economy" tickets sometimes have even more restrictive baggage policies that can catch parents by surprise at the gate.