Budesonide

Pregnancy

Human evidence is observational and mostly evaluates women with asthma using inhaled corticosteroids as a class; only a few studies isolate budesonide, and several report exposure in early pregnancy rather than separate trimester results. In the Swedish Medical Birth Registry, Källén et al. (1999) studied 2,014 infants exposed to inhaled budesonide early in pregnancy: congenital malformations were recorded in 3.8%, compared with a 3.5% population rate, and four orofacial clefts were observed versus 3.3 expected. The authors said a specific effect could not be ruled out, while judging a clinically important risk unlikely. Norjavaara and de Verdier (2003) studied 2,968 mothers reporting inhaled budesonide use in early pregnancy; infants had normal gestational age, birth weight, and length, with no increased stillbirth or multiple-birth rate. One author was affiliated with AstraZeneca R&D. A 2013 Danish population-based case-control study included 10,974 miscarriage cases and 109,740 controls. Current inhaled corticosteroid use was associated with early miscarriage (adjusted OR 1.22, 95% CI 1.01-1.49), but the study was not budesonide-specific; the authors discuss possible residual confounding by asthma and say the evidence did not warrant stopping inhaled corticosteroids. A 2025 UK cohort of 40,196 pregnancies with asthma found that inhaled corticosteroid prescriptions fell for 31% of women; reduced use was associated with exacerbations (adjusted OR 2.29, 95% CI 2.12-2.47), an observational class-level association. A Taiwan cohort published online in 2025 and in a 2026 journal issue included 4,538 pregnancies with asthma, with budesonide accounting for 1,109 of 1,713 ICS users. Overall ICS use was not associated with adverse fetal outcomes, but high-dose ICS use was associated with congenital anomalies versus low-to-moderate use (aOR 3.87, 95% CI 1.29-11.60); only 37 women were in the high-dose group. This signal is class-level, not budesonide-specific. The authors note limited sample size, possible model instability, residual confounding, and inability to perform trimester-specific dose analyses. A Korean cohort published in 2026 included 6,105 live-birth pregnancies with pre-pregnancy ICS use; first-trimester continuation versus discontinuation was not associated with increased maternal or neonatal outcomes, and the study did not report a budesonide-specific estimate. Its October 2026 erratum corrected the byline, not the results. A US cohort published in 2026 included 44,435 pregnancies and found no increased risk of major congenital malformations with ICS monotherapy or specified controller combinations; a cleft signal was reported for montelukast plus ICS with fewer than five events, not for ICS monotherapy. The Pulmicort label describes developmental effects in some animal studies after subcutaneous dosing but not in a rat inhalation study at about twice the maximum recommended human inhalation dose; these animal results do not establish human outcomes. Current EMA product information for Riltrava Aerosphere, an inhaled formoterol/glycopyrronium/budesonide combination first authorised in 2022, reports no or limited pregnancy data for the combination and says its use during pregnancy should be considered only if expected maternal benefit justifies potential fetal risk. The same product information separately states that data on inhaled budesonide in more than 2,500 exposed pregnancies indicate no increased teratogenic risk; this statement is not a budesonide-only product warning.

Breastfeeding

Fält et al. (2007) measured milk and plasma in eight mothers using inhaled budesonide 200 or 400 micrograms twice daily and estimated infant exposure at 0.3% of the maternal daily dose. The PubMed abstract reports blood samples from five infants, all below the limit of quantification; LactMed's record describes four infants, with all reported levels below quantification. The study measured drug concentrations and estimated exposure, not clinical infant outcomes. LactMed's January 2026 entry describes inhaled budesonide in milk as minute, with negligible infant exposure, and summarizes expert opinion that corticosteroids by inhaled, nasal, oral, and rectal routes are acceptable during breastfeeding. NHS Specialist Pharmacy Service says inhaled budesonide can be used; its general corticosteroid guidance applies to full-term, healthy infants. The Pulmicort label says budesonide is present in human milk, estimates the infant's available oral dose at approximately 0.3% to 1% of the maternal inhaled dose, and states that data on effects for the breastfed child or milk production are unavailable.

What was tested

Pregnancy studies used registry records and prescription data to compare congenital malformations, miscarriage, gestational age, birth size, stillbirth, and asthma exacerbations. Most were observational and could not fully separate medication effects from asthma severity, adherence, smoking, and other factors. Dose-specific evidence comes mainly from one Taiwan cohort with only 37 high-dose ICS users; that study could not provide trimester-specific results or a budesonide-only high-dose estimate. Breastfeeding research included one small milk-transfer study and measured drug levels rather than clinical effects in infants. The reviewed sources did not identify randomized trials designed to measure pregnancy outcomes from budesonide use.