Background:

Asthma in pregnant women is associated with several adverse pregnancy and delivery outcomes such as hypertension, preterm delivery and small for gestational age. Stress, sensitisation and lung function may contribute to these associations.

Aims and objectives:

To investigate the effect of sensitisation and stress on the association between maternal asthma and adverse perinatal outcomes, and to examine if lung function is also associated with adverse perinatal outcomes.

Methods:

Based on a cohort of 1693 pregnant women, 1554 were followed to birth and 252 performed spirometry during pregnancy. Data on asthma diagnoses, medication and stress from national registers were linked to cohort data. Associations between asthma with and without sensitisation and perinatal outcomes were estimated using logistic and linear regression. Z-scores for FEV1/FVC, FEV1 and FVC were used as exposures in secondary analyses. All analyses were adjusted for maternal stress.

Results:

In the cohort, 18 % (n=276) had asthma, and 61 % of these were sensitised (IgE ? 0.35kE/L, n=169) . Allergic asthma was associated with reduced mean gestational age by 0.5 weeks (95% CI -1.0 to -0.1), and mean lower birth weight (105 g) but we found no evidence of worse outcomes for non-allergic asthma. Stress did not appear to impact the associations. In general, the cohort was healthy with normal lung function ranges and no significant associations between lung function and adverse outcomes were detected.

Conclusion:

Allergic asthma may drive shorter gestational age and lower birth weight. In pregnant women within average lung function ranges there is likely no association with adverse perinatal outcomes.