Dad, it's a blood disorder. Some people just normally have a lower white blood count (though I doubt by MUCH). However, your girlfriend doesn't seem to be one of those people because she has been sick so much.
There are actually some pretty serious conditions that low white blood cell counts can point to. Hopefully they can pinpoint what is wrong and treat her for it.
Your other question mentions that you are both in school. You are wondering if you should stay home for a while and take care of the baby. How are you both making a living to support yourselves and your child? Are you living with parents? It's important to continue having medical insurance before you decide to quit school. Finish out THIS semester and make sure you and the baby are covered. If she is too sick to go to school, she may be able to cope with staying home with the baby. If so, then you need to stay in school so that you can qualify for a good job with a college degree.
I commend you for trying to find out how to help your child and his mother. My best to you all, and I hope that they can help her with this condition.
Dawn