Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. Severe perineal trauma occurred in 5.7% of patients with one midwife and 3.9% of patients with two midwives during the active stage of labour.

2. No other significant statistical difference was seen in maternal and fetal outcomes between the intervention and control group.

Evidence Rating Level: 1 (Excellent)

Study Rundown:

Severe perineal trauma (SPT) is defined as a third or fourth-degree tear of the perineum including the external anal sphincter. SPT is a major complication of vaginal delivery and is associated with long-term maternal morbidity. The Oneplus study is a randomized-controlled trial which evaluated the effectiveness of a second midwife at reducing the risk of SPT. Eligible patients were randomized to either one or two midwives during the active second stage of labour. The study found that participants with two midwives had a significantly lower rate of SPT compared to the standard care group with one midwife. The one midwife group also had a higher percentage of non-adherence to study protocol due to deemed risk to the mother or fetus. No other significant statistical differences were seen in secondary outcomes. Limitations of this study include lack of complete adherence to group assignment. Nonetheless, this study provides a promising option to reduce the risk of SPT during childbirth.

In-Depth [randomized controlled trial]:

The Oneplus study occurred in five obstetric units in Sweden. Eligible women were aged 18-47 years presenting for their first vaginal birth. Only singleton live fetuses in vertex presentation from gestational week 37+0 were screened for eligibility. Participants were randomized 1:1 to either the intervention group or control group. The intervention group (n = 1892) was assigned two midwives during the active stage of labour compared to one midwife in the control group (n = 1884) which was considered standard of care. After randomization, patients who had caesarean sections or instrumental births were excluded from the analysis. The total amounts of patients included in the ITT analysis in the intervention group and control group were 1546 and 1513, respectively. Non-adherence to study protocol occurred in 7.5% of the intervention group and 17.8% of the control group (OR 2.67, 2.12-3.36, p<0.0001). The main reason for non-adherence was concern for maternal or fetal wellbeing in the control group and lack of access to a 2nd midwife in the intervention group. The primary outcome was the percentage of participants with SPT (defined as third-degree or fourth-degree perineal tears involving the external sphincter) after spontaneous vaginal birth. SPT occurred in 3.9% of the intervention group compared with 5.7% of the control group (OR 0.68, 95% CI 0.49-0.95). There were no statistically significant secondary outcomes for both the neonate and the mother.

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