Forced entry into homes and offices and the planting of microphones was another tactic the Securitate used to extract information from the general population. Telephone conversations were routinely monitored, and all internal and international fax and telex communications were intercepted. In August 1977, when the Jiu Valley coal miners' unions went on strike, several leaders died prematurely, and it was later discovered that Securitate doctors had subjected them to five-minute chest X-rays in an attempt to have them develop cancer. After birth rates fell, Securitate agents were placed in gynecological wards while regular pregnancy tests were made mandatory for women of child-bearing age, with severe penalties for anyone who was found to have terminated a pregnancy.