Police arrested the doctor in November last year on child abuse charges, and he has been in custody since then, German media report.
The scope of the alleged crimes grew as police investigated the case and more victims came forward. Police say the risk of further offences means he cannot be released pending a likely trial.
The numerous assaults, including several alleged rapes, are said to have been carried out at the hospital where he worked between 2013 and 2015.
