My wife and I are trying to have a baby so she makes me wait all month to have sex so it coincides with her ovulation. I don't believe this is necessary. How long does it take for sperm to regenerate?

Let me begin by saying that making you wait so long actually has negative consequences, both for your relationship and for causing a pregnancy. Your wife may have read somewhere that when a couple is having a problem conceiving that the man should not have sex for a few days prior to when she is expected to ovulate and she figured that it would be better to wait even longer. But layman shouldn't guess about medical issues, and in this case she's guessed wrong. The "freshness" of sperm is also a factor in causing pregnancy and so a fertility specialist would most certainly tell you and your wife to engage in sex more often than once a month. Actually issues of fertility can be  complicated and if you are having problems, then you should consult with an expert.

But beyond the issue of causing a pregnancy, it is also very important that the relationship of the prospective parents is healthy. By making you wait so long to have sex is not going to be good for your relationship, and the tension that this will cause will also have a negative effect on your fertility. The strength of your love is a very important part of this process and you both should be doing whatever it takes to maximize those feelings, and that includes making love as often as possible. Now perhaps a fertility specialist may advise you to refrain from having sex for a few days a month, but that is the most that will be asked of you.