Influence of pregnancy-related diagnoses on sick-leave data in women aged 16-44.

Data on sickness absence frequently are used as a measure of morbidity and its social consequences in the employed population. The effects of sickness absence, as well as any possible differences in diagnoses among pregnant women as compared the sick leave data among the total population of women in fertile age have so far not been studied. The aim of this study was to investigate the relative contribution of pregnant women to the level of sickness absence, in general and in different diagnostic groups, as well as the extent to which sick-listed pregnant women can be identified through diagnoses on sickness certificates. In a cross-sectional study of all sick leave insured women aged 16-44 years (n = 24,481) in Linköping, Sweden (117,000 inhabitants), data from two population-based research registers were used, one of sickness absence for the whole population, one of sickness absence among pregnant women in the same population and year. Pregnant women (5%) had a significantly higher cumulative incidence of sickness absence (0.64) compared with all women (0.18) and accounted for 20% of the women listed as absent because of sickness. The duration of the sickness absence was also significantly longer among pregnant women, 44.8 days compared with 9.7 days among all women. Practically all diagnoses among pregnant women were related to pregnancy or back pain (93%). When using diagnoses on the sickness certificates, only 46% of all sick-listed pregnant women could be identified, suggesting methodological difficulties in studies on sickness absence. Studies on sickness absence among women of fertile age should also contain information on the proportion of sick-listed pregnant women, as a small proportion of pregnant women may have a deep impact on the results and conclusions among all women.