Perinatal outcomes in the pregnancies of asthmatic women: a prospective controlled analysis

Prior studies have found an increased incidence of adverse perinatal outcomes of pregnancies in asthmatic mothers, but these studies have been poorly controlled for asthma therapy and other confounding factors. The purpose of this study was to assess perinatal outcomes in actively managed pregnant asthmatic women as compared with matched nonasthmatic controls. Using an inception cohort design, we studied a volunteer sample of 486 pregnant (< 28 wk) women with documented asthma and 486 pregnant nonasthmatic controls with normal pulmonary function. Cases and controls were matched for age, smoking status, parity, and year of delivery. Asthma was managed with step therapy to prevent acute asthmatic episodes and asthma symptoms that interfered with sleep or normal activity. Chronic hypertension was significantly more common (p = 0.007) in asthmatic subjects (3.7%) than in matched controls (1.0%). However, no significant differences in incidences of preeclampsia, perinatal mortality, preterm births, low-birth-weight infants, intrauterine growth retardation, or congenital malformations were observed in the pregnancies of the asthmatic women as compared with the matched controls. Trends were observed toward relationships between more severe asthma requiring emergency therapy or corticosteroids and increased incidences of preeclampsia and low-birth-weight infants, but these associations were not statistically significant. These data suggest that the overall perinatal prognosis for women with actively managed asthma during pregnancy is comparable to that for the nonasthmatic population.

Increased transient tachypnea of the newborn in infants of asthmatic mothers

OBJECTIVE

To compare the incidence of transient tachypnea of the newborn (TTN) in infants of asthmatic vs nonasthmatic mothers.

RESEARCH DESIGN

Case-control analysis.

SETTING

Group model health maintenance organization.

PATIENTS

A volunteer sample of 294 pregnant asthmatic women and 294 pregnant nonasthmatic women with normal pulmonary function test results, matched on the basis of age and smoking status. All subjects entered the study before their third trimester of pregnancy. Subjects with multiple gestations and abortions (less than 20 weeks' gestation) were excluded.

INTERVENTION

Asthma was treated in the allergy department. Routine obstetric, neonatal, and pediatric care was provided to all patients by staff physicians.

MEASUREMENTS/RESULTS

Transient tachypnea occurred in 11 infants (3.7%) of asthmatic women and in one control infant (0.3%). There were no significant differences between asthmatic and matched control subjects in previously defined TTN risk factors, such as the occurrence of longer labors, failure to progress, cesarean sections, premature births, male sex, Apgar scores of less than 7 at 1 minute, or birth weight greater than 4 kg. Although infants of asthmatic mothers were more likely to exhibit wheezing by age 15 months compared with control infants (12.0% vs 3.2%), none of the infants with TTN manifested wheezing by age 15 months. No relationships could be identified in the asthmatic cohort between the occurrence of TTN and asthma severity or medication use (during the pregnancy in general or during labor and delivery in particular).

CONCLUSION

Although the mechanism is uncertain, maternal asthma appears to increase the risk of infant TTN.

Intrauterine growth is related to gestational pulmonary function in pregnant asthmatic women. Kaiser-Permanente Asthma and Pregnancy Study Group

Asthmatic mothers have been reported to deliver infants of lower mean birth weight than nonasthmatic mothers. This study examined the relationship between intrauterine growth and serial gestational spirometry in 352 pregnant asthmatic women who were prospectively treated and observed during pregnancy. A small (r = 0.11) but significant (p less than 0.04) direct correlation was demonstrated between infant birth weight and individual mean percent predicted FEV1 during pregnancy. In addition, lower maternal mean FEV1 during pregnancy was associated with increased incidences of birth weight in the lower quartile of the infant population (p = 0.002) and ponderal indices less than 2.2 (suggestive of asymmetric intrauterine growth retardation) (p less than 0.05), but not with increased incidences of preterm (less than 38 weeks) or low birth weight (less than 2,500 g) infants. Although lower mean birth weight occurred in infants of smoking compared with nonsmoking asthmatic mothers (p less than 0.02), the relationships of lower FEV1 to birth weight in the lower quartile of the population (odds ratio 3.0, p = 0.002) and ponderal indices less than 2.2 (odds ratio 2.8, p less than 0.05) were shown by multivariate analysis to be above and beyond the influence of smoking and also independent of the effects of age, parity, acute asthmatic episodes, and asthma medications. These data support the hypothesis that lower maternal gestational FEV1 during pregnancy is related to intrauterine growth retardation and suggest that the goals of gestational asthma therapy should include optimization of pulmonary function in addition to achievement of symptomatic control.

The safety of inhaled beta-agonist bronchodilators during pregnancy

To assess the safety of inhaled beta-agonist bronchodilators during pregnancy, perinatal outcomes in 259 prospectively managed women with asthma using these medications during pregnancy were compared to perinatal outcomes in 101 concurrently followed pregnant subjects with asthma not using inhaled bronchodilators and to perinatal outcomes in 295 concurrently followed pregnant control subjects without asthma. No significant differences between women with asthma using inhaled bronchodilators and subjects not receiving inhaled bronchodilators were found in the following parameters: perinatal mortality, congenital malformations, preterm births, low birth weight infants, mean birth weight, small for gestational age or low ponderal index infants, Apgar scores, labor/delivery complications, or postpartum bleeding. Increased incidences of maternal chronic and pregnancy-induced hypertension and transient tachypnea of the neonate were observed in the pregnancies of subjects with asthma using regular inhaled bronchodilators compared to control subjects, but a logistic regression analysis within the sample of subjects with asthma did not significantly associate the use of inhaled bronchodilators with these outcomes. In the light of the known substantial perinatal risks of severe, uncontrolled asthma and the relatively sparse evidence of human gestational safety for alternative asthma medications, these data support the use of inhaled beta-agonist bronchodilators as part of the management of asthma during pregnancy.