The Win32 version of Apache runs a parent version of the code and a single multi-threaded child that handles all requests.
ThreadsPerChild number Default number: 50 Server config
Currently this directive is only relevant to Win32. You may need to increase this number from 50, the default, if your site gets a lot of simultaneous hits. The name ThreadsPerChild may suggest that there can be more than one child process in a Win32 installation, but this is not currently the case.[††]
[††] If you really want to know: Win32 will not distribute requests among multiple children like Unix does. The first process to open a port gets all the connections, whether it is ready for them or not. Microsoft claims this is a Good Thing. We're not so sure.