Fig. 1.

Myometrial contractility in relation to maternal age. a Representative isometric recordings of spontaneously contracting myometrial strips obtained from a (i) 32-year old, (ii) 48-year old and (iii) 62-year old woman undergoing hysterectomy. Strips were placed under a resting tension of 2 mN and superfused continually with physiological saline solution (pH 7.4) at 37 °C. b Plots of spontaneous contractile activity (quantified as area under the contraction curve, (AUC, in arbitary units, au) of strips of pregnant and/or non-pregnant myometrium obtained from women undergoing planned CS delivery or hysterectomy respectively, against age. Pregnant women are denoted by blue circles and non-pregnant women are denoted by red squares. Green asterisk was from a 72-year old woman but produced no spontaneous contractions (and was not included in the analysis). Spearman’s rank test found a significant negative correlation between integral of force and age (i; combined data, r = −0.379, P < 0.01, n = 104). (ii, iii) Plots of non-pregnant and pregnant women separately. A significant negative correlation between integral of force and age was found for non-pregnant women alone (ii; r = −0.529, P = 0.008, n = 24). In contrast, no significant correlation was found for pregnant women (iii; n = 80). (Color figure online)