Is formoterol (long-acting beta-2 agonist) safe to use during pregnancy?

Formoterol Use During Pregnancy

Formoterol is safe to use during pregnancy when needed for asthma control, as the risks of poorly controlled asthma to both mother and fetus substantially outweigh any theoretical medication risks. 1, 2

Safety Profile and Evidence Base

Limited human data exists for formoterol specifically, but animal studies suggest low risk, and the pharmacologic profile is similar to short-acting beta-agonists like albuterol which have extensive reassuring pregnancy data. 1, 2

• The FDA classifies formoterol with limited pregnancy data, noting that beta-agonists may interfere with uterine contractility, though animal studies showed adverse effects only at exposures 730-29,000 times the maximum recommended human dose 3
• A comparative study of 547 pregnancies found no statistically significant differences in low birth weight, preterm birth, or small-for-gestational-age infants between salmeterol and formoterol users 4
• If a woman was well-controlled on formoterol before pregnancy, continuing the same medication is acceptable and preferred over switching 2

Clinical Recommendations for Asthma Management

For moderate persistent asthma during pregnancy, combination therapy with low-dose inhaled corticosteroid plus long-acting beta-agonist is a preferred treatment option. 1, 2

When to Use Formoterol:

• Continue formoterol if the patient was previously well-controlled on this medication before pregnancy 2
• For new initiations, salmeterol has historically been preferred due to longer U.S. experience, though formoterol is acceptable 1, 2
• Use the lowest effective dose necessary to maintain asthma control 2

Combination Therapy Considerations:

• Budesonide is the preferred inhaled corticosteroid component due to the most extensive safety data (over 52,000 first-trimester exposures) 2, 5
• Evidence from non-pregnant adults shows adding long-acting beta-agonist to low-dose inhaled corticosteroid provides superior asthma control compared to increasing corticosteroid dose alone 1

Critical Management Principles

Uncontrolled asthma poses definite risks including perinatal mortality, preeclampsia, and low birth weight—risks that exceed any potential medication concerns. 2, 6

• Asthma exacerbations during pregnancy must be managed aggressively due to potential for maternal hypoxia and adverse fetal outcomes 2
• Monthly evaluation of asthma control and lung function is recommended throughout pregnancy 2, 6
• The course of asthma improves in one-third of women and worsens in one-third during pregnancy, justifying regular monitoring 6

Common Pitfalls to Avoid

• Never discontinue asthma medications during pregnancy due to unfounded safety concerns—this leads to poor asthma control and increases risks to both mother and fetus 2
• Avoid unnecessarily switching from formoterol to salmeterol if the patient was previously well-controlled on formoterol 2
• Do not fail to aggressively manage exacerbations during pregnancy, as maternal hypoxia directly threatens fetal well-being 2
• Avoid first-trimester medication exposure when possible, though maintaining control takes priority over timing concerns 1

Labor and Delivery Considerations

• Use of formoterol during labor should be restricted to situations where benefits clearly outweigh risks due to potential interference with uterine contractility 3
• Short-acting beta-agonists like albuterol are preferred for acute symptom relief throughout pregnancy including during labor 5, 6