Wednesday, July 30, 2008

Declining fertility of Danish women

While at the Department of Growth and Reproduction, Rigshospitalet, I was approached by Professor Tina Kold Jensen, who asked me if I could assist in a register based study of Danish womens reproductive health. We obtained access to a considerable amount of data, since Denmark have a long tradition of compiling high quality registers of birth, death, immigration, induced abortions, and hospitalization data. I undertook the task of cleaning and ordering this data allowing analysis of the impact of assisted reproduction on the fertility rate in Denmark with respect to native Danish women. Denmark is one of the few countries in the Western World with a steady fertility rate, however, we were able to show that the fertility rate was upheld only be the use of artificial reproduction. It has been argued that the falling fertility rate observed in younger cohorts is due to postponement of child bearing, however, we also observe a cohort effect showing a decline of the induced abortion rate among Danish teenage girls - is this because contraception use has improoved, or is this linked the fact that 20% or young Danish men have a sperm concentration below 20 mio sperms/milliliter - the WHO threshold of impaired reproductive function?

The below figure shows the accumulated Total conception rate (birth rate + abortion rate) with and without the contribution of assisted reproduction.

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