Counterproductive

It is comical the looks I get when I say before you start IVF you are put on birth control pills. 
Yes, I realize it sounds crazy and counterproductive... 

From a fertility blogger who summed it up quite well,
You’ll be on birth control pills from 14 to 21 days. Taking these may seem counterproductive, however they do an important thing. They help get your hormones under some kind of exact control in the cycle just before your actual IVF cycle. Using them has proved to also reduce your chances of Ovarian Hyperstimulation and ovarian cysts, therefore increasing your chances for a successful IVF.  As mentioned before, not all women will be given birth control pills.  An example would be a patient with a lower ovarian reserve (fewer eggs).

So, now you know that it helps to time the IVF cycle, get hormones in check and possibly help OHSS to not happen.