Table 3.
Increases in stillbirth rates connected with being born in time periods which put infants at risk during the 1918–19 influenza epidemic in Derbyshire: different causes of stillbirth examined separately
| Odds ratios associated with periods of birtha | ||
|---|---|---|
| July 1918–April 1919 | Sept. 1918–Jan. 1919 | |
| All causes | 1.247* | 1.535*** |
| Health of the mother | 1.782*** | 1.928*** |
| Complications of pregnancyb | 2.165* | 2.586** |
| Complications of labour | 0.822 | 1.042 |
| Congenital malformations | 1.092 | 1.406 |
| Other causes | 0.997 | 1.397 |
a
Odds ratios give the multiplicative increase in mortality associated with period of birth, compared to a value of 1.000 for all other months in the period 1917–1922. Each odds ratio is derived from a separate multivariate logistic analysis, in which other variables are also controlled (see text for details).
b
The fit of this model was questionable.
***
Significant at 1% level.
**
Significant at 5% level.
*
Significant at 10% level.
Source: Derbyshire health visitor data.