Table 2. Adjusted rate ratios for frequency of term births by day of the week, compared to the overall average, by onset of labour and mode of birth (99% confidence intervals in brackets).
| Onset | Spontaneous | Induced | No labour | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mode | Spontaneous | Emergency CS | Instrumental | Spontaneous | Emergency CS | Instrumental | Elective CS | Emergency CS | ||||||||
| Mon | 1.00 | (0.99, 1.00) | 1.02 | (1.01, 1.04) | 1.01 | (0.99, 1.02) | 0.87 | (0.86, 0.88) | 0.89 | (0.87, 0.90) | 0.88 | (0.87, 0.90) | 1.53 | (1.52, 1.55) | 1.05 | (1.01, 1.09) |
| Tues | 1.01 | (1.00, 1.01) | 1.02 | (1.00, 1.03) | 1.00 | (0.99, 1.01) | 1.02 | (1.01, 1.03) | 0.98 | (0.97, 1.00) | 0.99 | (0.97, 1.01) | 1.38 | (1.37, 1.40) | 1.06 | (1.02, 1.09) |
| Wed | 1.01 | (1.01, 1.02) | 1.01 | (1.00, 1.02) | 1.01 | (1.00, 1.02) | 1.05 | (1.04, 1.06) | 1.04 | (1.02, 1.05) | 1.03 | (1.01, 1.05) | 1.36 | (1.34, 1.37) | 1.07 | (1.03, 1.10) |
| Thurs | 1.01 | (1.01, 1.02) | 1.01 | (1.00, 1.02) | 1.01 | (1.00, 1.02) | 1.07 | (1.06, 1.08) | 1.06 | (1.04, 1.07) | 1.06 | (1.04, 1.08) | 1.41 | (1.40, 1.43) | 1.08 | (1.05, 1.12) |
| Fri | 1.01 | (1.01, 1.02) | 0.99 | (0.98, 1.01) | 1.00 | (0.99, 1.01) | 1.10 | (1.09, 1.11) | 1.09 | (1.07, 1.10) | 1.06 | (1.04, 1.07) | 1.36 | (1.35, 1.38) | 1.09 | (1.06, 1.13) |
| Sat | 0.99 | (0.99, 1.00) | 0.97 | (0.95, 0.98) | 0.98 | (0.97, 0.99) | 1.04 | (1.03, 1.05) | 1.03 | (1.01, 1.05) | 1.04 | (1.03, 1.06) | 0.08 | (0.08, 0.09) | 0.86 | (0.84, 0.89) |
| Sun | 0.98 | (0.97, 0.98) | 0.99 | (0.98, 1.00) | 1.00 | (0.99, 1.01) | 0.88 | (0.87, 0.89) | 0.95 | (0.93, 0.96) | 0.96 | (0.94, 0.97) | 0.06 | (0.05, 0.06) | 0.83 | (0.80, 0.86) |
| Holiday | 0.98 | (0.97, 0.99) | 0.99 | (0.96, 1.02) | 0.98 | (0.96, 1.01) | 0.88 | (0.86, 0.91) | 0.92 | (0.88, 0.96) | 0.92 | (0.88, 0.97) | 0.09 | (0.08, 0.10) | 0.84 | (0.76, 0.92) |
| Christmas | 0.93 | (0.90, 0.95) | 0.88 | (0.82, 0.95) | 0.97 | (0.92, 1.03) | 0.61 | (0.57, 0.65) | 0.79 | (0.72, 0.87) | 0.81 | (0.74, 0.90) | 0.05 | (0.04, 0.06) | 0.72 | (0.58, 0.88) |
| Before holidayolHoldhOLD | 1.00 | (0.98, 1.01) | 0.96 | (0.92, 1.00) | 1.00 | (0.97, 1.04) | 1.10 | (1.06, 1.13) | 1.08 | (1.03, 1.13) | 1.08 | (1.03, 1.14) | 1.43 | (1.39, 1.48) | 1.11 | (1.01, 1.21) |
| After holiday | 0.99 | (0.97, 1.00) | 1.02 | (0.99, 1.06) | 1.00 | (0.97, 1.03) | 0.87 | (0.84, 0.90) | 0.86 | (0.82, 0.91) | 0.88 | (0.83, 0.93) | 1.62 | (1.58, 1.67) | 0.99 | (0.90, 1.10) |
| Adj. R2 | 0.843 | 0.423 | 0.623 | 0.826 | 0.664 | 0.737 | 0.972 | 0.628 | ||||||||
| % Dev | 1.5% | 1.9% | 0.4% | 18.7% | 7.2% | 4.6% | 94.6% | 9.3% | ||||||||
| N | 2,401,010 | 308,248 | 425,955 | 577,544 | 188,413 | 162,882 | 441,500 | 84,384 | ||||||||
Adjusted rate ratios compare the predicted number of births on each type of day to the overall average, within each group (column), after adjusting for yearly cycle and trend. In all models, ‘type of day’ was statistically significant with p < .001 (likelihood ratio test, df = 10). Before Holiday: the last weekday before a holiday period. After Holiday: the first weekday after a holiday period. Adj R2: Adjusted R2 value for the whole model. % Dev: the percentage of total deviance explained by type of day. CS: caesarean section.