Conference room space is always really hard to get at Cisco. A lot of male co-workers have started taking call in the 'mother's room' since it is only used 10% of the time. However, it makes me uncomfortable for me to go in and use it to start breastfeedning because I am worried about interrupting someone's conference call...
Is this room designated as a space for female workers to take care of children? if it is, then politely remind them the purpose and designation of the room. If it is not, then I recommend you schedule the room (if possible) and talking to the management team for a designated room.
If it is designated and the male co-workers are using it for which it was not intended then bring this to the attention of management.
It is easy to talk to fathers as they will understand you plight. However, single men and some single women will have a hard time understanding the need for privacy.
I know it is frustrating but being nice is the best way. We have a similar room where I work. Even being of the same sex, I have had to explain to many of my male co-workers the necessity of privacy. I sometimes fall back to, well I can them into your office. This usually does the trick. Many of my female co-workers just go into the ladies room. Management has added small sofas to help out.