Intended for healthcare professionals

Letters Hormonal contraception and thrombosis

Authors’ reply to Costescu and Waddington

BMJ 2013; 346 doi: (Published 16 April 2013) Cite this as: BMJ 2013;346:f2369
  1. Frits R Rosendaal, professor in clinical epidemiology1,
  2. Frans M Helmerhorst, professor in clinical epidemiology of fertility1
  1. 1Leiden University Medical Center, 2300 RC Leiden, Netherlands
  1. F.R.Rosendaal{at}

Costescu and Waddington think that there is no reason for a European Medicines Agency review or any concern because oral contraceptives containing third generation progestogens, drospirenone, and cyprotereone acetate are all equally safe.1 2

Their main point is that all retrospective studies are fraught with bias. Undoubtedly, any study can be biased—we dealt with this point more than …

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