Relative perinatal safety of salmeterol vs formoterol and fluticasone vs budesonide use during pregnancy

Recent asthma guidelines endorse the safety of long-acting β2-agonists (LABAs) and of mild and moderate doses of inhaled corticosteroids (ICSs) when required to control asthma during pregnancy, yet do not state a preferred medication within each class.

To estimate the relative perinatal safety with the use of salmeterol and formoterol (LABAs) and that of fluticasone and budesonide (ICSs) during pregnancy.

A subcohort of pregnancies from asthmatic women was selected from health care administrative databases of Quebec, Canada. Low birth weight (LBW) was defined as weight less than 2,500 g, preterm birth (PB) as delivery before 37 weeks of gestation, and small for gestational age (SGA) as a birth weight below the 10th percentile. The effect of treatment with salmeterol vs formoterol and fluticasone vs budesonide on the outcomes was determined with generalized estimating equation models.

The LABA and ICS subcohorts were composed of 547 (385 salmeterol and 162 formoterol users) and 3,798 (3,190 fluticasone and 608 budesonide users) pregnancies, respectively. No statistically significant differences were observed for LBW (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.44-1.88), PB (OR, 1.11; 95% CI, 0.56-2.23), and SGA (OR, 1.16; 95% CI, 0.67-2.02) newborns between women exposed to salmeterol vs formoterol or between women exposed to fluticasone vs budesonide (LBW: OR, 1.08; 95% CI, 0.76-1.52; PB: OR, 1.07; 95% CI, 0.78-1.49; and SGA, OR: 1.10; 95% CI, 0.85-1.44).

This study does not provide evidence of greater perinatal safety for one LABA or one ICS over the other.