It will depend on your obstetrician how many cycles of clomid she/he will use before rethinking treatment. After a few cycles on clomid the endometrium can (but not always) become compromised. This is remedied by having a cycle or two off treatment and resuming. It is generally thought that if clomid is successful it will be within 5 cycles at the most.

Like Monnie I conceived on my first clomid cycle of 50mgs. Sadly that baby is now an angel. This TTC time I have had 2 unsuccessful clomid cycles - I will soon be ovulating on my third cycle so I will let you know.