Steroids that induce lung maturation acutely affect higher cortical function: a fetal magnetoencephalography study.

Objective: To investigate whether steroids that induce lung maturation have acute effects on higher cortical function in the human fetus.

Methods: Cortical auditory-evoked responses (CAERs) were recorded from 10 singleton fetuses between 29 and 34 gestational weeks by fetal magnetoencephalography (fMEG) using transabdominal auditory stimulation prior to and within 3 hours after administering 2 × 12 mg of betamethasone, at an interval of 18 and 24 hours.

Results: The components of the CAER complex were categorized according to their latency: P2pm (186 + 20 ms, 90%), N2pm (260 + 34 ms, 50%), P3pm (474 + 36, 50%). In almost all of these cases the peak latencies of the fetal P2pm (P = .042) and P3pm (P = .043) were delayed after exposure to betamethasone (Wilcoxon rank test). The trend was also observable in N2pm (P = .08).

Conclusions: Administration of betamethasone to expectant mothers was associated with acute change in higher cortical functions in the exposed fetuses. Implications regarding functional brain development need further evaluation.