Amniotic fluid concentrations of SP-B in women at term with and without labor stratified by gender of the fetus. There was no significant difference in the median amniotic fluid concentration of SP-B stratified by fetal gender in both the term in labor and term not in labor groups (term no labor SP-B, female: median 0.5 μg/ml, range 0.2–1.9 μg/ml vs. male: median 0.5 μg/ml, range 0.2–1.1 μg/ml; p=0.9 and term in labor SP-B, female: median 0.4 μg/ml, range 0.2–0.9 μg/ml vs. male: median 0.5 μg/ml, range 0.04–1.3 μg/ml; p=0.8).