In Reply:

In Reply: We thank Drs. Gupta and Srikandhan for their interest in our article in the January 2025 issue.1 In their Letter, Gupta and Srikandhan correctly emphasize the lack of available data regarding long-term outcomes in children who were exposed to cystic fibrosis transmembrane conductance regulator (CFTR) modulators prenatally. This is the focus of the ongoing MAYFLOWERS study (Prospective Study of Pregnancy in Women With Cystic Fibrosis), which is collecting data from the first trimester of pregnancy through age 24 months. Another study, HOPE:CF (Health Outcomes of Parents with Cystic Fibrosis, NCT05829694),2 is a long-term observational study evaluating the intersection of parenthood with the management of cystic fibrosis (CF). Although not available at the time of our original review, a multicenter study by Jain et al3 provides additional insight into maternal CF outcomes during pregnancy. Covering 10 years, this retrospective review demonstrates improved lung function during pregnancy in people exposed to modulators compared with those unexposed. Such studies will continue to offer clinical guidance for health care providers counseling prospective parents about the risks and benefits of using CFTR modulators in pregnancy. Finally, regarding the need for further understanding of immunoreactive trypsinogen values in modulator-exposed children, Patel et al4 evaluated immunoreactive trypsinogen levels in elexacaftor–tezacaftor–ivacaftor–exposed neonates and found the values to be lower than those expected for CF carriers. However, this is not universally true; we recently have cared for two neonates with CF exposed to elexacaftor–tezacaftor–ivacaftor in utero, both of whom had immunoreactive trypsinogen values higher than the floating daily cutoff. Therefore, it behooves all clinicians to remember that the Newborn Screening System is, in fact, a screening test, and further clinical workup should be considered in compatible circumstances.