The influence of maternal respiratory allergy on obstetrics and perinatal outcomes: A nested case-control study.

OBJECTIVE: To evaluate the influence of respiratory allergy on obstetrics and perinatal outcomes. METHODS: A nested case-control retrospective study on 41 035 pregnant women. Obstetrics and perinatal outcomes of women with or without respiratory allergy were compared. Rates of preterm delivery (<37 weeks of gestation), low birth weight (<2500 g), neonatal acidosis (pH < 7.20), low 5-min APGAR score (<7), cesarean section rate and indications, and perinatal morbidity and mortality were analyzed. Results are expressed as number and percentages. χ2 and Fisher exact tests were used for comparisons. Logistic regression was used. Statistical significance was set at 95% level (P < 0.05). RESULTS: A total of 724 (1.8%) patients had respiratory allergy, and their rates of preterm delivery and low birth weight were significantly higher than those of control women (both P < 0.001). Nevertheless, analyzing the causes, multiple gestation rate was significantly higher in this group, and adjusting by this, no statistical difference was found in any of the perinatal outcomes studied. In addition, in vitro fertilization and sterility were also significantly higher in the respiratory allergy group (both P < 0.001). CONCLUSION: Women with respiratory allergy are at higher risks of prematurity and low birth weight but these results are mediated by sterility, in vitro fertilization, and multiple gestation rate. Nonetheless, participation of inflammatory mechanisms should be further studied.