Baseline characteristics of the study participants stratified by children who had current asthma during the study period and children who did not [n (%)].

* P value was estimated based on Chi-square test or Fisher’s exact test.†Active maternal smoking during pregnancy or presence of a smoker in the home during pregnancy.‡Active maternal smoking during the first year after delivery, current maternal smoking, or presence of a smoker in the home after delivery until the present time.§Having had a pet dog or cat after delivery until the present time.Size of the wheal produced by the cockroach antigen ≥3 mm and larger than size of the wheal produced by histamine.Baseline characteristics of the study participants stratified by children who had current asthma during the study period and children who did not [n (%)].* P值基于卡方检验（Chi-square test）或费希尔精确检验（Fisher’s exact test）估算得出。 † 妊娠期母亲主动吸烟，或妊娠期家庭中存在吸烟者。 ‡ 分娩后第一年母亲主动吸烟、当前母亲仍在吸烟，或分娩后至当前家庭中存在吸烟者。 § 分娩后至今饲养过宠物犬或猫。 蟑螂抗原诱导的风团直径≥3mm，且大于组胺诱导的风团直径。 按研究期间当前罹患哮喘的儿童与未罹患哮喘的儿童分层后，研究参与者的基线特征[n（%）]。