Congenital bladder exstrophy associated with Duogynon hormonal pregnancy tests—Signal for teratogenicity or consumer report bias?

Abstract A combination of ethinylestradiol and 10 mg norethisterone under the brand names of Duogynon (Germany) or Primodos (UK) was used as a pregnancy test until the 1970s. Until very recently there was continuing public concern about the safety of these drugs and legal proceedings were instituted against the medicinal authorization holder. Given the lack of epidemiological studies focusing on Duogynon/Primodos, the present study evaluates 296 consumer reports of the German Duogynon database and compares the reported birth defects with data from a population based birth registry. The most striking result is an increase of bladder exstrophy (OR = 37.27; 95%-CI 14.56–95.28). Neural tube defects (OR = 2.99; 95%-CI 1.85–4.84) and renal agenesis (OR = 2.53; 95%-CI 1.17–5.45) were also significantly increased. Bladder exstrophy may be a yet undetected teratogenic effect of Duogynon, but may also represent a reporting bias. The present study highlights the difficulties of evaluating consumer reports which may be influenced by public media.