18/month son keeps getting cold, sinus infection,ear infection. wife had negative prenatal screening and son had negative newborn screening. cf?

Unlikely: Unlikely with those two tests negative. If he is in daycare, that is most likely the answer. He'll catch something every 4 - 6 weeks. If not, allergies, GERD & immune system issues could be the cause.

Doubt it: Young children frequently get colds, called upper respiratory infections (URI's), which often lead to ear infections. 3-4 ear infections per ear in the first few years may be considered average, with some children even more prone than others due to different exposures to germs like being in a daycare settings etc. While he should get better by age 3-4 yrs, make sure to get his hearing checked.

More information pls: If he has had recurrent sinus infections/pneumonia, CF is still possible even with a negative initial screening test. Children with ciliary defects may have ear infections/sinusitis more often and the episodes are more prolonged. They are also susceptible to pneumonia. More information is needed though such as the type of infection/duration/response to treatment and family history .