Is it normal for young children to have recurring fluid buildup in the ear behind the eardrum?

Fluid: It isnt normal but it is common. The eustachian tubes dont work well until age 7 or 8. If fluid build up is causing hearing loss or speech problems, then pressure equalizing tubes may be very helpful. If fluid build-up lasts more than a couple months or occurs more than 3 times per year then tubes may help. See ent.

Yes: Studies in day care centers suggest the persistence of middle ear fluid for up to 3 months in the first year in patients with no symptoms.The occurrence is aggravated by smaller drainage tubes in kids heads,allergies & recurrent URI's. As they approach age 8-9 they achieve 90% of adult head size & the issue is uncommon.