Although I have explained why I am skeptical regarding the evidence of a post-fertilization mechanism from OCs, if there were a way to decrease even the potential chance, I would be interested. Surprisingly, in my reading of the literature there is a way for women who choose to take OCs to significantly decrease the chance that an embryo will be affected by the so-called "hostile endometrium". I have yet to see this promoted (especially by those who swear that OCS cause "chemical abortions"), yet is almost universally consistent in the literature. It is also a technique which is very doable. The secret is simple:
Take the pill every day at about the same time every day.
In every study that I have seen, the vast majority of "breakthrough ovulations" occur because of non-perfect use of the pill. In other words, a more consistent use of the pill will minimize the risk for ovulation, which will decrease the chance that a conceived embryo will not implant.
So if you choose to take OCs, and wish to minimize the chance that you could cause a "chemical abortion", then take it consistently.