A few important questions to clear up some things:
1) Are your birds housed together?
2) Did you purchase them together, and if so, were they housed together then and did they get along then?
3) If they are housed together, how big is their home? Is it a new cage or the one they came with?
4) Did they ever get along or is this new behavior? If it's new, what might have changed (other than hormones)?
5) Is one bird newer than the other?
It may have nothing to do with their sexes--some birds simply do not like one another, just like people. Fighting can be caused by lots of things: stress, jealousy, hormones, etc. Some birds can never get along and will even fight by screaming at each other from across the room from different cages, but lots of birds can be SLOWLY integrated into the flock. Your first step should be to separate them, giving them different cages, if they are not hugely upset by the idea (I said immediately before, but that is based on the idea that they weren't always living together! Hence the needing more details thing...). If you think separation will cause greater stress and the male is not doing harmful attacks on the female, you could get a second cage and leave the doors between them open to acclimate them to being in separate spaces. You can work from there on slowly introducing/re-introducing them to one another, first by moving their cages closer together slowly and seeing how they react to each other in that situation. More details on the situation (the ones above and any others you can think of!) would be great for more on how to handle it.
