Table 2. Comparison of the contractile properties between myometrium from singleton and twin pregnancies.
| Parameter | Singleton (n = 35) | Twin (n = 48) | P value |
| Force amplitude (mN) | 3.37 (2.15–6.19) | 2.21 (1.06–4.38) | ns |
| Duration (min) | 1.02 (0.77–1.40) | 0.79 (0.59–0.98) | P = 0.004* |
| Frequency (no. 10 min−1) | 1.11 (0.71–1.6) | 1.56 (0.99–2.16) | P = 0.010* |
| Integral of force (AUC, a.u.) | 7.76 (4.68–13.17) | 6.66 (3.23–16.19) | ns |
| Force amplitude normalised to high K, % | 86.9 (65.2–99.4) | 80.0 (48.4–89.8) | ns |
| Integral of force under high K (AUC, a.u.) | 6.18 (2.31–10.59) | 3.16 (2.13–6.18) | ns |
| % increase in force amplitude under OT, (%) | +41.4 (18.9–83.7) | +63.4 (35.1–118.0) | ns |
| % increase in integral of force (AUC) under OT, (%) | +522.6 (383.7–773.8) | +556.4 (176.9–1139.1) | ns |
Data are represented by medians (IQR). * represents a significant difference (P<0.05) found by Mann Whitney U test (ns = not significant). High K is 40 mM to depolarize the myometrium. Contraction frequency measured over at least 4 contractions. OT; oxytocin, 10 nM.