Table 1

Variation within versus between women in peak and cumulative salivary PG, measured during two menstrual cycles

No. of cycles (subjects)First cycle mean, pg/ml (s.e.)ICC95% CIa
Peak PG (3-day running mean)24 (12)120.2 (5.8)0.680.22–0.89
Cumulative PG (days+2 to+9); midcycle (day 0) set by:
Reverse datingb24 (12)722.6 (55.5)0.720.30–0.91
Urine LH testing20 (10)776.0 (67.8)0.760.32–0.93
Rise in salivary PG22 (11)754.3 (61.8)0.760.37–0.92
  • a CI, confidence interval.

  • b Reverse dating identifies day 0 by subtracting 14 days from the onset of the subsequent menses.