Ecological association between operative vaginal delivery and obstetric and birth trauma

Abstract

Background: Increased use of operative vaginal delivery (use of forceps, vacuum or other device) has been recommended to address high rates of cesarean delivery. We sought to determine the association between rates of operative vaginal delivery and obstetric trauma and severe birth trauma.

Methods: We carried out an ecological analysis of term, singleton deliveries in 4 Canadian provinces (2004-2014) using data from the Canadian Institute for Health Information. The primary exposure was mode of delivery. The primary outcomes were obstetric trauma and severe birth trauma.

Results: Data on 1 938 913 deliveries were analyzed. The rate of obstetric trauma was 7.2% in nulliparous women, and 2.2% and 2.7% among parous women without and with a previous cesarean delivery, respectively, and rates of severe birth trauma were 2.1, 1.7 and 0.7 per 1000, respectively. Each 1% absolute increase in rates of operative vaginal delivery was associated with a higher frequency of obstetric trauma among nulliparous women (adjusted rate ratio [ARR] 1.06, 95% confidence interval [CI] 1.05-1.06), parous women without a previous cesarean delivery (ARR 1.10, 95% CI 1.08-1.13) and parous women with a previous cesarean delivery (ARR 1.11, 95% CI 1.07-1.16). Operative vaginal delivery was associated with more frequent severe birth trauma, but only in nulliparous women (ARR 1.05, 95% CI 1.03-1.07). In nulliparous women, sequential vacuum and forceps instrumentation was associated with the largest increase in obstetric trauma (ARR 1.44, 95% CI 1.35-1.55) and birth trauma (ARR 1.53, 95% CI 1.03-2.27).

Interpretation: Increases in population rates of operative vaginal delivery are associated with higher population rates of obstetric trauma, and in nulliparous women with severe birth trauma.

Figure 1:

Temporal trends in obstetric trauma stratified by parity and obstetric history (A), stratified by mode of delivery among nulliparous women (B), among parous women without a previous cesarean delivery (C), among women with a previous cesarean delivery (D), among term, singleton deliveries, Canada, 2004–2014. Using the Cochran-Armitage test for linear trend in proportions, p < 0.001 for overall obstetric trauma trend among nulliparous and parous women (with and without a previous cesarean delivery); p < 0.001 for obstetric trauma trend among operative vaginal delivery in all 3 groups; p < 0.0001, 0.03, and 0.01 for obstetric trauma trend among spontaneous vaginal delivery in nulliparous women, parous women without cesarean delivery, and women with a previous cesarean delivery, respectively; and p = 0.2, 0.07 and < 0.0001 for these trends in cesarean delivery among the same 3 groups, respectively. Note: CD = cesarean delivery, OVD = operative vaginal delivery, SVD = spontaneous vaginal delivery.

Figure 2:

Temporal trends in severe birth trauma stratified by parity and obstetric history (A), stratified by mode of delivery among nulliparous women (B), among parous women without a previous cesarean delivery (C), among women with a previous cesarean delivery (D), among term, singleton deliveries, Canada, 2004–2014. Using the Cochran-Armitage test for linear trend in proportions, p = 0.0001 for the trend in severe birth trauma in operative vaginal delivery among nulliparous women. All other p values for severe birth trauma trend > 0.05. Note: CD = cesarean delivery, OVD = operative vaginal delivery, SVD = spontaneous vaginal delivery.