No. They aren't mature enough yet. That is very dangerous for a female and effects her pups as well. That is BYB/puppy mill breeding and considered very bad breeding practices. For a female it is minimum third season or 2 to 3 years of age for them to be mature enough for any breeding. Males are generally recommended about the same ages. Preferably with recommended health testing. For pits they are recommended to be looked at for HD and OFA won't grade until two because there is too much growth and not a mature skeleton to look at (and should say something). Nine months is a puppy, a baby. That isn't even old enough for them to be physically mature enough to safely begin any conditioning (muscle ect.). Like breeding 10 year old humans, do you see any way that would be good or only a whole bunch of bad things that would come of it including the effects on their baby they raised not being physically, mentally or emotionally mature enough to begin with themselves?
You would definitely want to look into what things are needed to be a good breeder and have good pups that are worth producing (and your breed as well) and how not to contribute to the dogs being put down in shelters (Pits being number one and mass poorly produced). If the dogs are only 9 months there is plenty of time. You are creating lives (and intentionally risking them) that you have a lot of responsibility for how their futures turn out. The majority of the responsibility, their health, their homes, their behavior, whether they end up in the shelter 8 or 9 times out of ten (with millions and millions in shelters) even though they are no longer in your home (and you probably have no idea) it can almost all be traced back to something you as their breeder may or may not have done or known most of the time. It is important and worth it to make sure you are doing things the right way to try and minimise all of that. Here are some links to get you started. Good Luck.
http://www.apbt.info/tiki-index.php http://www.workingpitbull.com/howcanihelp2.htm
http://www.realpitbull.com/myths.html
q6300945.html
http://www.learntobreed.com/
http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
q7351465.html
q5762034.html#a2906893
http://www.boxerworld.com/rescue/excuses/
You would definitely want to look into what things are needed to be a good breeder and have good pups that are worth producing (and your breed as well) and how not to contribute to the dogs being put down in shelters (Pits being number one and mass poorly produced). If the dogs are only 9 months there is plenty of time. You are creating lives (and intentionally risking them) that you have a lot of responsibility for how their futures turn out. The majority of the responsibility, their health, their homes, their behavior, whether they end up in the shelter 8 or 9 times out of ten (with millions and millions in shelters) even though they are no longer in your home (and you probably have no idea) it can almost all be traced back to something you as their breeder may or may not have done or known most of the time. It is important and worth it to make sure you are doing things the right way to try and minimise all of that. Here are some links to get you started. Good Luck.
http://www.apbt.info/tiki-index.php http://www.workingpitbull.com/howcanihelp2.htm
http://www.realpitbull.com/myths.html
q6300945.html
http://www.learntobreed.com/
http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
q7351465.html
q5762034.html#a2906893
http://www.boxerworld.com/rescue/excuses/