Figure 5. Effects of postnatal age on baroreflex sensitivity.

Postnatal age effects on BRS calculated using frequency and time domain methods during quiet sleep in the first 6 months of life (n= 30). BRS was estimated in the frequency domain (BRS_sp) from the gain of the transfer function between heart period and systolic blood pressure changes within a LF band of 0.04–0.15 Hz. In the time domain, BRS was estimated using spontaneous sequence analysis with a variable heart period delay (BRS_seqvar) and a 5 beat fixed delay (BRS). †P < 0.05, 2–3 months vs. 5–6 months; *P < 0.05, 5–6 months vs. 2–4 weeks. Note that baroreflex sensitivity increases with postnatal age using all three modes of analysis.