Usually. While the intended effect of such birth control is to eliminate ovulation altogether, in a certain percentage of cases, ovulation may still occur which of course may lead to fertilization in a sexual active woman. The hormones contained in the "pill" prevent the fertilized eggs from implanting themselves in the uterine wall, ergo a kind of abortion.
The pills with lower doses of hormones, and some of the other monthly pills may only stop ovulation less than 60% of the time. This is the unspoken secret of the modern-day birth control pill.
News to me. I’ll check it out.