SFTPA1 and newborn respiratory distress syndrome: The frequency of the SP-A1 6A4 and/or SP-A2 1A5 haplotype was relatively low (at least one of these haplotypes was present in 27 infants or 23.3% of the study population), but comparable or even higher to that of known risk factors for RDS, such as complications of pregnancy (33 infants or 28.4%), gestational age ≤35 weeks (23 infants or 19.8%), and maternal preexistent morbidity (7 infants or 6%).