Statistical Analyses
Bivariate analyses were performed using Fisher’s exact test or t-tests
as appropriate. Multivariable analyses were then performed using
logistic regression to evaluate the association between PCP-diagnosed
asthma and API status, adjusting for variables that had
p-value<0.10 in the bivariate analysis plus a priorifactors including gender, C-section, and tobacco exposure. Potential
confounders (p-value<0.10) included maternal BMI, education,
and oral contraceptive use; birthweight; placenta weight; pets at home
at 6 months; age at daycare start;
gastroesophageal reflux disease
(GERD) by 12 months; acute otitis media (AOM) by 18 months;
bronchiolitis, croup, or pneumonia prior to PCP asthma diagnosis; and
cord blood 25(OH)D, CC16, adiponectin, and IL12p40. These were retained
in the final model if their coefficients were significant, or they
contributed significantly to the best model fit. Ap -value<0.05 was considered statistically significant.
SPSS® v17.0 (IBM, Armonk, NY) was used throughout.