| Author | Number of Cases | Study Design | Injection Site/ Administration Mode | HA Dose | Results |
| Colacioppo et al. [5] | 160 (80 in the experimental and 80 in the placebo group) | RCT | Posterior region of the perineum | - 20.000 turbidity- reducing units (5 mL) | - No difference in the incidence of perineal trauma between both groups - No difference in the incidence of first-, second-, third-, or fourth-degree tears between both groups - No difference in the incidence of episiotomy between both groups |
| Spallicci et al. [6] | 168 (83 in the experimental group and 85 in the placebo group) | RCT | Cervix | - 20,000 UI of lyophilized HA (5 mL) | - Significant decrease in the average duration of labor in the experimental group |
| O’Leary et al. [8] | 100 (50 each in the experimental and control groups) | RCT (2-arm design with randomized selection) | Perineal body, hymen, and any previous episiotomy scars | 5 - 10 mL HA (contained 750 - 1550 turbidity-reducing units of HA) | - Lower incidence of perineal trauma in the experimental group - No difference in the incidence of episiotomy between the groups - No difference in the incidence of first- and second-degree perineal trauma between both groups - No side effects |
| Scarabotto and Riesco [9] | 139 (71 in the intervention and 68 in the control group) | RCT | Posterior region of the perineum | 5 mL HA (20,000 turbidity-reducing unit) | - Significant differences in the frequency of perineal trauma (39.4% in the intervention group vs 76.5% in controls) - Significant differences in the degree of spontaneous laceration (0.0% in the intervention group vs 82.4% in controls) - Significant differences in the frequency of lacerations in the posterior perineum (54.2% in the intervention group vs 84.3% in controls) - No difference in the incidence of episiotomy between the groups - No side effects |
| Gupta et al. [10] | 75 (50 in the experimental and 25 in the control group) | Interventional | Cervix | 20,000 UI lyophilized HA | - Labor was accelerated and shortened by an average of 1.95 hours in the experimental group - Cervical dilation rate was increased in the experimental group - No effect on uterine contractions in both groups - No cervical tears in both groups |
| Kimbell [11] | 2749 (2002 in the experimental and 747 in the control group) | Interventional | Intramuscular | 0.5 mg EM alone (n = 198), 0.25 mg EM + HA 1 mg (n = 254), and 0.5 mg EM + HA 1 mg (n = 1748) | - Post-partum hemorrhage rate decreased in the experimental group (0.9% vs 6.4% in controls) - Manual placenta removal rate was not appreciably influenced (1.6 % in controls vs 1.1% for cases) - Blood loss was lower in the experimental group - Stage III labor was shortened in the experimental group |