Whether or not you ovulate on oral contraceptive type birth control will depend on what type you are taking. You do not ovulate when taking combination oral contraceptives. Fifty percent of women do not ovulate when taking progestin only contraceptives. Which means that some women do still ovulate when taking this type of birth control. 
How Do Combination Oral Contraceptive Pills Work?
Inhibiting ovulation is the goal of this combination oral contraceptive pills. Here’s how they work.
The body begins ovulating when estrogen levels in the body are low. During menstruation, the estrogen levels in the body are low, which signals the pituitary gland to begin producing follicle-stimulating hormone (FHS). This is the hormone that is responsible for causing a woman’s egg to mature.
Combination oral contraceptive pills (OCPs) contain synthetic forms of estrogen and progesterone. By increasing the levels of these hormones, the body does not produce the hormones responsible for progression of ovulation. They prevent pregnancy by inhibiting ovulation. OCPs also induce thickening of the cervical mucus, which impedes the sperm from reaching the egg.
How Do Progestin Only Oral Contraceptives Work?
About fifty percent of women ovulate when taking progestin only pills.
Rather than blocking hormones that induce ovulation, progestin only pills, often referred to as mini-pills, work by thickening the cervical mucus, which impedes the sperm from reaching the egg. Once a woman takes the pill, the thickening will occur within four hours and lasts for twenty hours. Because this pill is temporarily making changes in the body rather than altering the phases of the menstrual cycle, it is imperative when taking this type of birth control that it is taken diligently at the same time every single day.
This type of birth control is often used by women who are breastfeeding or want something short-term.
How Long after I Stop the Pill Will I Ovulate?
For many women, the monthly cycle and ovulation will resume as normal. This means that menstruation will begin within four weeks following cessation of taking oral contraceptives.
Some women experience post-pill amenorrhea, which is the absence of a menstrual period in women of reproductive age. Because oral contraceptives inhibit the body from producing the hormones involved with ovulation and menstruation, the body may take a while to begin producing them again.
Because oral contraceptive forms of birth control are only effective while taking them, women who had irregular ovulation and menstrual periods will likely find this will again be the case when they stop taking the pill.
SARINA SCHRAGER, M.D; Am Fam Physician
Abnormal Uterine Bleeding Associated with Hormonal Contraception
2002 May 15;65(10):2073-2081.
Centers for Disease Control
US National Library of Medicine-Medline
Oral Contraceptives: Drug Info