The alleged captor of three women who were kidnapped in the US and held hostage for a decade subjected his victims to "mind games" and reportedly threatened one of them while she was pregnant that if her baby died during delivery, she would too.

Details continue to emerge of the terror allegedly inflicted by 52-year-old Ariel Castro in a Cleveland home on Amanda Berry, now 27, Michelle Knight, 32, and Gina DeJesus, 23, after each was abducted between 2002 and 2004.

DeJesus is the only one of the three who does not believe she became pregnant to Castro despite his repeated rapes, local television station WEWS reported.

The women were allegedly kept bound by chains and ropes in Castro's basement, and each was subject to years of sexual and physical abuse.