Asthma in Pregnancy: ICS Continuation Not Linked to Higher Risk

Key Takeaways

• In women in Korea with asthma who had used ICS before pregnancy, first-trimester continuation and discontinuation were the exposure patterns compared in a nationwide live-birth cohort.
• First-trimester ICS discontinuation was more common than continuation, occurring in 65.5% versus 34.5% of pregnancies with prepregnancy ICS use.
• In weighted analyses, first-trimester ICS continuation was not associated with a statistically significant increase in measured maternal outcomes versus discontinuation.
• Measured neonatal outcomes also were not significantly increased with ICS continuation, although low birth weight and congenital malformation estimates were numerically above 1 and remained nonsignificant.

Asthma control can become harder to maintain once pregnancy is recognized, when concern about fetal exposure often prompts early changes in controller therapy. For pregnant women with asthma, inhaled corticosteroids (ICS) often anchor control before conception, yet the first trimester is also when exposure concerns may drive discontinuation. That clinical tension has left uncertainty over whether staying on ICS early in gestation carries measurable maternal or neonatal consequences in a nationwide Korean live-birth cohort.

In the JAMA Network Open cohort of first-trimester inhaled corticosteroid continuation in pregnancy, investigators used a nationwide, population-based mother-child linked health care database in Korea to study live births from April 1, 2010, through December 31, 2022. Eligible participants were women aged 15 to 50 years with asthma who had filled at least 2 ICS prescriptions in the 6 months before the last menstrual period. Among 3,909,084 pregnancies, 6,105 involved prepregnancy ICS use for asthma. Continuation meant at least 1 ICS prescription during the first trimester, and discontinuation meant no prescription in that period. Maternal outcomes included preeclampsia, gestational diabetes, obstructed labor, antepartum hemorrhage, premature rupture of membranes, and preterm birth; neonatal outcomes included hypoxia or asphyxia, low birth weight, and congenital malformations.

Among pregnancies with prepregnancy ICS use, 2,108 women (34.5%) continued ICS in the first trimester and 3,997 (65.5%) discontinued. For gestational diabetes, risks were 145.6 versus 131.9 per 1,000 pregnancies, with a weighted RR of 1.05 (95% CI 0.90-1.22). Preterm birth occurred at 131.4 versus 128.6 per 1,000 pregnancies, with a weighted RR of 0.95 (95% CI 0.82-1.11).

Among neonatal outcomes, low birth weight was numerically higher with continuation, but the estimate remained nonsignificant. Congenital malformations occurred at 57.6 versus 42.2 per 1,000 pregnancies, with a weighted RR of 1.22 (95% CI 0.94-1.56). Overall, the weighted analyses did not associate first-trimester ICS continuation with increased measured maternal or neonatal outcomes.

Because the comparison was observational, the findings support association reporting rather than causal inference. The cohort was limited to live births in Korea, which bounds applicability. The authors characterized the overall pattern as reassuring.

In this nationwide Korean cohort, continuing ICS early in pregnancy was not associated with increased measured maternal or neonatal outcomes despite frequent discontinuation. The authors said the findings add reassurance within this Korean live-birth population.

Clinician Questions

Which pregnancies were included in the Korean asthma cohort on first-trimester ICS continuation?

The cohort included live births in Korea to women aged 15 to 50 years with asthma who had filled at least 2 ICS prescriptions in the 6 months before the last menstrual period, so the findings apply to pregnancies with prepregnancy ICS use rather than to all pregnancies affected by asthma.

How were ICS continuation and discontinuation defined during early pregnancy in women with asthma?

Inhaled corticosteroid continuation meant at least 1 ICS prescription during the first trimester, whereas discontinuation meant no ICS prescription during that period among women with asthma who had been using ICS before pregnancy.

What pregnancy outcomes were measured in the cohort evaluating first-trimester ICS use?

Maternal outcomes were preeclampsia, gestational diabetes, obstructed labor, antepartum hemorrhage, premature rupture of membranes, and preterm birth, while neonatal outcomes were hypoxia or asphyxia, low birth weight, and congenital malformations.