Figure 4. Characteristics of ECoG HV-LV 3–5 days prior to spontaneous onset of labour (A) and 1 day before spontaneous onset of labour (B).

a, ECoG periodicity; b, percentage of time spent in LV (○) and HV (•) (means ± s.e.m. for each 4 h); c, duration of LV and HV epochs. The filled bar represents hours of darkness. Values are given as means ± s.e.m. (n = 9). *P < 0.05.