Objective: To compare the incidence of transient tachypnea of the newborn (TTN) in infants of asthmatic vs nonasthmatic mothers.
Research design: Case-control analysis.
Setting: Group model health maintenance organization.
Patients: A volunteer sample of 294 pregnant asthmatic women and 294 pregnant nonasthmatic women with normal pulmonary function test results, matched on the basis of age and smoking status. All subjects entered the study before their third trimester of pregnancy. Subjects with multiple gestations and abortions (less than 20 weeks' gestation) were excluded.
Intervention: Asthma was treated in the allergy department. Routine obstetric, neonatal, and pediatric care was provided to all patients by staff physicians.
Measurements/results: Transient tachypnea occurred in 11 infants (3.7%) of asthmatic women and in one control infant (0.3%). There were no significant differences between asthmatic and matched control subjects in previously defined TTN risk factors, such as the occurrence of longer labors, failure to progress, cesarean sections, premature births, male sex, Apgar scores of less than 7 at 1 minute, or birth weight greater than 4 kg. Although infants of asthmatic mothers were more likely to exhibit wheezing by age 15 months compared with control infants (12.0% vs 3.2%), none of the infants with TTN manifested wheezing by age 15 months. No relationships could be identified in the asthmatic cohort between the occurrence of TTN and asthma severity or medication use (during the pregnancy in general or during labor and delivery in particular).
Conclusion: Although the mechanism is uncertain, maternal asthma appears to increase the risk of infant TTN.