gms | German Medical Science

Background: We will consider if there are long term influences of circumstances near the birth on the health status. On the one hand, there is a weekly rhythm. Considering birth data between 1920 till 1929 we have to take into account that the social conditions and the medical care during these times differed much from current conditions. In order to measure the health status of older persons we use drug costs. On the other hand, there are seasonal influences. This consideration is more common, we will state the respective results using our data base in a later paper. In the discussion of seasonal influences one has to take into account shifts due to holidays, especially for long term drug prescriptions (cf. [10]). The first discussion of the influence of the weekday of birth on a large data basis was given in [6], [8] using birth data of the seventies, our data focus on some decades before. Furthermore the number of births with respect to the weekday differs much from the present-day pattern. Related backgrounds are discussed in [1], [2], [3], [4], [5], [7], [9], [11], [12].

Materials and Methods: We use health and care insurance data from a German federal state. With respect to sufficient statistical significance in the care insurance field we can go as far back as people born in 1905 by using data from 1998 till 2006, in the health insurance data from 2006 one can track back until 1920. Although we only need aggregated data, such data with a weekday resolution are rarely available. For calculations we use Microsoft Excel and Mathematica from Wolfram Research.

Results: The difference of the drug costs with respect to the weekday of birth and the average weekly costs shows the same pattern in both birth groups 1920-1924 and 1925-1929 for every weekday (cf. Figure 1 [Fig. 1]). The largest positive cost differences (approx. +2%) we get on Saturdays. The lowest costs are found on Thursdays (approx. - 2%). The other days with increased costs are Monday and Friday, days with lower drug costs are Tuesday, Wednesday and Sunday. Drug costs increase in average by 1.5% per year. With respect to the care insurance data there are increased birth rates for people born 1905-1929 on weekends (cf. Figure 2 [Fig. 2]) and reduced birthrates on Tuesdays and Wednesdays. The other days show no observable pattern. If we use the health insurance data, we get almost the same results with some shift from Saturday to Friday (cf. Figure 3 [Fig. 3]). We also can use a weighted combination of health and care insurance data (cf. Figure 4 [Fig. 4]) ignoring the fact that a simple combination of the datasets would count especially younger individuals twice. There is a long term shift (100 years) from Sunday to Tuesday and Wednesday births (cf. Figure 5 [Fig. 5]) using 5 year birth data smoothing.

Conclusion: In order to consider the time between birth and measurements using data of health and care insurance the following statements and guesses can be made regarding the results. In scenario 1 more births measured in insurance data can be caused by more real births in the considered time 1915-1930. That can be due to different conception/fertilization possibilities depending on the day of the week. A bias may be caused by migration. In scenario 2 the day of birth may cause different survival expectancies in the critical first three days after birth and the related health conditions during these days. So here we take a look at drug costs in dependence of the day of birth. As we already stated, drug costs increase in the mean by 1.5% per year between the considered two age groups. As a modelling consideration one can use drug costs as a proxy for biological age, comparing it with chronological age. Due to the considered age dependent drug cost increase we can suspect a strong connection to the residual life expectancy. Thursday births around 90 years ago have a one year higher residual life expectancy. Saturday births have a one year lower residual life expectancy, Sunday births have 4 months higher residual life expectancy. In contrast to the situation stated in [6] lower perinatal mortality rates at weekends can be caused by the fact that quality of care is higher due to family background. In those times specialist obstetric services have been less common compared to later decades. It is quite important, that the psycho-social near birth circumstances 90 years ago may induce significant differences today.