Abstract
To explore associations between exposures to medicines prescribed for asthma and their discontinuation in pregnancy and preterm birth [<37 or <32 weeks], SGA [<10th and <3rd centiles], and breastfeeding at 6-8 weeks. Design. A population-based cohort study. Setting. The Secure Anonymised Information Linkage [SAIL] databank in Wales, linking maternal primary care data with infant outcomes. Population. 107,573, 105,331, and 38,725 infants born 2000-2010 with information on premature birth, SGA and breastfeeding respectively, after exclusions. Exposures. maternal prescriptions for asthma medicines or their discontinuation in pregnancy. Methods. Odds ratios for adverse pregnancy outcomes were calculated for the exposed versus the unexposed population, adjusted for smoking, parity, age and socio-economic status. Prescriptions for asthma, whether continued or discontinued during pregnancy, were associated with birth at<32 weeks' gestation, SGA <10th centile, and no breastfeeding (aOR 1.33 [1.10-1.61], 1.10 [1.03-1.18], 0.93 [0.87-1.01]). Discontinuation of asthma medicines in pregnancy was associated with birth at<37 weeks' and <32 weeks' gestation (aOR 1.22 [1.06-1.41], 1.53 [1.11-2.10]). All medicines examined, except ICS and SABA prescribed alone, were associated with SGA <10th centile. Prescription of asthma medicines before or during pregnancy was associated with higher prevalence of adverse perinatal outcomes, particularly if prescriptions were discontinued during pregnancy. Women discontinuing medicines during pregnancy could be identified from prescription records. The impact of targeting close monitoring and breastfeeding support warrants exploration.
Highlights
The prevalence of asthma in pregnancy has increased worldwide [1,2,3]
Prescription of asthma medicines before or during pregnancy was associated with higher prevalence of adverse perinatal outcomes, if prescriptions were discontinued
While older [5] and smaller [6, 7] studies were reassuring, asthma [3, 8] accompanied by symptoms [5, 9] or suboptimal spirometry recordings [10] has been associated with growth restriction [small for gestational age [SGA]]
Summary
The prevalence of asthma in pregnancy has increased worldwide [1,2,3]. Approximately 9% of pregnant women in the UK are prescribed medicines for asthma, more than elsewhere in Europe [4]. There is no consensus on the effect of asthma or prescription of asthma medicines on perinatal outcomes. Active management of asthma may reduce premature birth [13], and uncontrolled asthma increases the risk of adverse perinatal outcomes [3], but there is less information on medicines prescribed for asthma. Few RCTs have examined the impact of asthma medicines in pregnancy on perinatal outcomes, and no differences were seen in any of the small trials located [14]. Short-Acting Beta Agonists [SABA] have not been associated with growth restriction or premature birth, studies have relatively low numbers [15], and there is no consensus on the impact of Long-Acting Beta Agonists [LABA] [15,16,17]. Up to 50% pregnant women discontinue asthma medicines, often without professional advice, frequently worsening asthma and outcomes [1, 9, 14]
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