Results
The number of births at the CHWC in both the pre and post intervention period is summarised in Table 1. The number of singleton births in the pre intervention period was 17355 and the number of births in the post intervention period was 4592. The annual rates of preterm and early term births including iatrogenic births with no medical indication (NMI) are shown in Table 2. The trends for preterm and early term births including iatrogenic births with NMI are shown in Figure 1. The average rates pre intervention are illustrated with the black horizontal bar and noted in the attached text box and the initiation of the intervention is illustrated with a red vertical bar. Table 3 demonstrates the differences between pre and post intervention with respect to preterm and early term births.
The rate of PTB (20-36 weeks) within the post intervention period was 8.75% which was significantly lower than the preceding 5 years with an average of 9.74 % (OR 0.88 95% CI 0.79-0.99 p= 0.05). This resulted in a 10% reduction in rates of PTB. When the rates of PTB were separated into grouped gestational ages there was a significant reduction in the 20-23+6 weeks gestation group, 0.82% v 0.52% (OR 0.63 95% CI 0.41 – 0.97 p=0.03), a non-significant reduction for the 24-27+6 week gestation group, 0.79% v 0.67% (OR 0.84 95% CI 0.57 –1.25 p = 0.40), a significant reduction for the 28-31+6 weeks gestational group, 1.46% v 0.73% (OR 0.73 95% CI 0.54 – 1.00 p=0.05) and a non-significant increase for the 32-36 weeks gestational group, 4.47% v 4.5% (OR 1.00 95% CI 0.86 – 1.17 p=0.92).
The rates of early term births (37-38+6 weeks) within the post intervention period was 25.78% which was a significant increase in births compared to the preceding five years with an average of 23.95% (OR 1.10 95% CI 1.02 – 1.18 p=0.009). When further analysed, there was a significant reduction in iatrogenic early term births with NMI, 18.84% v 12.33% (OR 0.73 95% CI 0.61 – 0.87 p=0.0001) which equated to a 34% reduction in iatrogenic early term births with NMI.
Table 4 displays the estimated number of PTB and iatrogenic early term births with NMI averted or delayed post intervention. The estimated number of averted or delayed PTBs based on the 10% reduction was 45 and the estimated number of iatrogenic early term births with no medical indication that were averted or delayed based on the 34% reduction was 77.