To determine the incidence of recurrent wheezing in moderate-to-late preterm infants in the first 3 years of life.

This is a multicenter, prospective, observational study of Spanish newborns from the SAREPREM study. This study included 977 infants born at 32 to 35 weeks' gestation with no additional co-morbidities identified within the first 14 days of life. Newborns were recruited from October 15, 2006, to April 14, 2008, and followed for the first 3 years of life.

Trained researchers administered questionnaires during 7 study visits. Baseline data were collected at 2–4 weeks of life. The following visits, occurring every 6 months, collected data to include type of wheezing episodes that occurred and associated risk or protective factors. Environmental skin prick testing and spirometry were obtained at year 3.

Of the 977 newborns identified, 670 were followed for the complete 3 years. At 1 year, 401 of 766 (52.3%) reported no wheeze, 221 of 766 (28.8%) reported infrequent wheeze occurring less than 3 times per year, and 144 of 766 (18.8%) reported recurrent wheeze occurring more than 3 times per year. Incidence of recurrent wheeze stayed the same for year 2 (19%) but declined in year 3 (13.3%). Hospitalization for wheeze was more common in the first year of life (6.3%) in comparison with year 2 (2.4%) and year 3 (0.75%). Incidence of wheezing based on gestational age demonstrated no statistical difference. Recurrent wheezing in year 2 and 3 were associated with the following risk factors: day care attendance, acetaminophen use during pregnancy, need of mechanical ventilation, atopic dermatitis, and male sex. The only protective risk factor identified was use of palivizumab prophylaxis for RSV given in the first year of life with decrease in recurrent wheezing in year 3. Sensitization to environmental allergens was not found to be different between children reporting wheeze or without. Spirometry was completed and able to be analyzed in 187 of 670 (27.9%). Children with recurrent wheeze had significantly lower FEV0.5 in comparison with children without wheeze or intermittent wheeze.

In otherwise healthy moderate-to-late preterm newborns, persistent wheezing was associated with increased lung morbidity as demonstrated by lower FEV0.5.

This study highlights that the incidence of wheeze in otherwise healthy moderate-to-late preterm infants is common affecting more than half of this population. Ideally, this population should be followed for a longer period of time, such as five years to understand if allergic sensitization is truly a risk factor, as most children are not sensitized to environmental allergens by the age of 3, in addition to having more reliable spirometry results with a larger number of patients being able to participate.