Table 1.
Risk ratios comparing the number of spontaneous deliveries in the week after the transition into daylight saving time (spring) with the mean number of spontaneous deliveries in the week before and the week after this period
| Number of spontaneous deliveries |
RR (95% CI) | ||
|---|---|---|---|
| Comparison unit | Observed* | Expected† | |
| Whole week | 18 519.2 | 18 433.5 | 1.005 (0.990 to 1.019) |
| Sunday‡ | 2549.2 | 2563.5 | 0.994 (0.956 to 1.034) |
| Monday | 2774.0 | 2733.0 | 1.015 (0.978 to 1.053) |
| Tuesday | 2716.0 | 2700.0 | 1.006 (0.968 to 1.044) |
| Wednesday | 2739.0 | 2693.5 | 1.017 (0.979 to 1.056) |
| Thursday | 2621.0 | 2658.0 | 0.986 (0.949 to 1.025) |
| Friday | 2609.0 | 2604.5 | 1.002 (0.964 to 1.041) |
| Saturday | 2511.0 | 2481.0 | 1.012 (0.973 to 1.052) |
*Observed is the number of spontaneous deliveries during the week following the spring transition.
†Expected is the number of spontaneous deliveries during the week before and the week after the week following the spring transition divided by two.
‡The number of deliveries on the Sunday following the transition into daylight saving time was adjusted for the shorter day length (23 instead of 24 hours).
CI, confidence interval; RR, risk ratio.