Inhaled corticosteroids during pregnancy: a review of methodologic issues.
BACKGROUND
There is evidence in the literature that inhaled corticosteroids (ICSs) are safe for pregnant women with asthma and their infants. Although this is useful information about ICS use during pregnancy, some articles must be viewed cautiously because of lack of power and adjustment for potentially important confounding variables.


OBJECTIVE
To summarize evidence on the potential effects of ICSs to treat asthma in pregnant mothers and their children with particular focus on study power.


METHODS
Studies published before September 1, 2007, and focusing mainly on ICS use for asthma treatment during pregnancy were researched in Pubmed and the Cochrane Library. Post hoc power calculations were completed using data reported in the published articles.


RESULTS
Twenty-three studies that evaluated the associations between ICS use during pregnancy and maternal and/or perinatal outcomes were retained. Only six studies on the association between ICS use and maternal outcomes reported significant results; five studies found significant associations between ICS use and perinatal outcomes. Regarding non-significant results, two studies on maternal outcomes and seven studies on perinatal outcomes had a power higher than 80% to detect a relative risk of 1.5 or a mean birth weight difference of 500 g.


CONCLUSIONS
While there currently is some degree of evidence to support the safety of ICS use during pregnancy, this review highlights the limited statistical power of several studies published in this area.
Breton
Marie-Claude
MC
Faculty of Pharmacy, Université de Montréal, C.P. 6128, succursale Centre-ville, Montreal, Que., Canada H3C 3J7.
Martel
Marie-Josée
MJ
Vilain
Anne
A
Blais
Lucie
L
D000280:Administration, Inhalation; D018927:Anti-Asthmatic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy*; D019317:Evidence-Based Medicine; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D011256:Pregnancy Outcome
D018927:Anti-Asthmatic Agents; D005938:Glucocorticoids