When Do You Ovulate?

Do You Ovulate on the Pill?

When Do You Ovulate?
Ovulation. Photo Courtesy of Science Picture Co/Getty Images

Do you know when you ovulate? Are you wondering if you ovulate on the pill? For most women, no, you do no ovulate when you are on the pill. Some women also do not ovulate when using other forms of hormonal birth control. I'll explain the reason for this in a moment—but first, let's talk about the first question... knowing when you ovulate. In order to be able to know the answer to this question, there are a few things that you must first take into consideration.

First and foremost is knowing exactly what happens when you ovulate, how often it occurs, and what ovulation actually means.

Many women confuse ovulation with having their periods, with PMS, and with conception, so it is important to know your facts. How come? Well, the reason why you may want to know when you ovulate could factor into the type of information you may be looking for. Do you need to know your ovulation date as part of a natural family-planning method to avoid pregnancy, or are you trying to maximize your opportunity to get pregnant?

The Basics

To understand when you ovulate, let’s start with some basic definitions:

  • Ovulation: ovulation refers to the time a mature egg (possibly more) is released from your ovary. At this time, an egg is available to being fertilized by a sperm—this leads to conception.​
  • Menstrual Period: Your menstrual period begins on the first day of your next menstrual cycle. Your period occurs as a result of the hormonal changes that take place when an egg has been released, is not fertilized, and dies. These hormones tell your body that no pregnancy has occurred, so your uterus begins to shed its lining to prepare for your next ovulation day.

    Who Ovulates?

    Having a menstrual period is usually an indication that you have ovulated. Ovulation typically occurs in the middle of your menstrual cycle. So when you have a period, this means that you are beginning your next cycle and have likely ovulated during your previous cycle. This is one area that can get you in trouble.

    Many women who have not had a period in a while (due to stress, miscarriage, breastfeeding, having given birth, etc.) use their periods to determine that they are fertile (ovulating) again. But, if you have been having unprotected sex before this time, you could be at risk for pregnancy since you would have ovulated already—before your period resumes.

    If you have excessive monthly bleeding, infertility issues, or irregular menstrual cycles, you may or may not be ovulating. If this applies to you, it is important that you try to determine if and when you ovulate. You may need to seek the help of a doctor and have blood tests to confirm if you have ovulated or are ovulating.

    Most women’s menstrual cycles last 28 to 35 days. There seems to be very little cycle variability among women between the ages of 20 and 40. But, you may experience considerable cycle variability during the first five to seven years after you first get your period as well as during the last 10 years before menopause (the stopping of your cycle). Typically, your menstrual-cycle length peaks at about age 25 to 30 years and then slowly drops—which is why women in their 40s may have somewhat shorter cycles.

    Women Using the Pill or Hormonal Contraception

    Listen up, ladies, because, in my experience, it appears many of you do not realize what I am about to tell you.

    As I mentioned before, if you are reliably using a hormonal contraceptive (especially a combination method that contains both estrogen and progestin)... are you listening? You do not ovulate. So, to repeat, the answer to: do you ovulate on the pill is NO!

    The hormones in the pill and many of these hormonal methods stop you from ovulatingwhich is what makes them effective birth control methods. Stop the egg from being released = no egg = nothing for the sperm to fertilize = no baby.

    So, if you are using the pill or hormonal birth control methods, please do not try to track, either by temperature, charts, kits, etc., your cycle to figure out when you ovulate...

    because you do not ovulate! You do not have "more fertile days" in the middle of the month. You are no more at risk for pregnancy than any other day of the month. For those of you who use hormonal methods, the risk factors for contraception failure have to do with if you forget to take pills, change your patch or if your NuvaRing falls out, etc. With these methods, you need to make sure that there are enough hormones in your body to stop you from ovulation. If you miss too many pills (especially during the first week of a pill pack or at the end of Week 3, where you need to have enough hormone built up to protect you against the hormone-free Week 4), you may be at risk for ovulating.

    What Happens Up to and After You Ovulate?

    Your normal menstrual cycle is a synchronized cycle of hormonal changes that produces a mature egg (oocyte) to be released. In order to have the most accurate information and learn what exactly is going on in your body, I consulted an article on UpToDate—a trusted electronic reference used by many doctors and patients. According to this excerpt from UpToDate:

    "The first day of menses represents the first day of the cycle (Day 1). The cycle is then divided into two phases: follicular and luteal. The follicular phase begins with the onset of menses and ends on the day of the luteinizing hormone (LH) surge. The luteal phase begins on the day of the LH surge and ends at the onset of the next menses."

    "Follicular Phase: The early follicular phase in humans is the time when the ovary is the least hormonally active, resulting in low serum estradiol and progesterone concentrations. Release from the negative feedback effects of estradiol, progesterone, results in a late luteal/early follicular phase increase in gonadotropin-releasing hormone (GnRH) and a subsequent increase in serum follicle-stimulating hormone (FSH) concentrations. The modest increase in FSH secretion in the early follicular phase gradually stimulates folliculogenesis and estradiol production. By the late follicular phase, a single dominant follicle has been selected. The dominant follicle increases in size by about 2 mm per day until a mature size of 20 to 26 mm is reached. Rising serum estradiol concentrations result in gradual thickening of the uterine endometrium and an increase in the amount and "stringiness" of the cervical mucus. Many women are able to detect this change in mucus character."

    "Luteal Phase: Serum estradiol concentrations continue to rise until they reach a peak approximately one day before ovulation. Then, a unique neuroendocrine phenomenon occurs: the mid-cycle surge, resulting in a 10-fold increase in serum LH concentrations and a smaller rise in serum FSH concentrations. The oocyte is released from the follicle at the surface of the ovary approximately 36 hours after the LH surge. It then travels down the fallopian tube to the uterine cavity. A gradual decrease in LH secretion results in a gradual fall in progesterone and estradiol production by the corpus luteum in the absence of a fertilized oocyte. If, however, the oocyte becomes fertilized, it implants in the endometrium several days after ovulation. The decline in estradiol and progesterone release from the resolving corpus luteum results sequentially in the loss of endometrial blood supply, endometrial sloughing, and the onset of menses approximately 14 days after the LH surge."

    So, in normal language... each month a series of events occur within your body. The follicular phase starts with the first day of your period (which is considered Day 1 of your cycle):

    • Low estrogen and progesterone levels help your brain produce the gonadotropin-releasing hormone (GnRH)
    • The GnRH will then activate the pituitary gland to release the follicle-stimulating hormone (FSH)
    • FSH triggers your follicle to grow, and as it does, it causes the production of more estrogen
    • The follicle grows, your uterine walls become thicker (preparing for possible implantation) and your cervical mucus becomes thinner and stretchier
    • Your estrogen levels increase over the next 10 days and usually peak one day before you ovulate (in a 28-day cycle, this typically occurs on Day 13)
    • This estrogen peak initiates the luteinizing hormone (LH) surge

    After this surge occurs, you are now in the luteal phase of your cycle:

    • The increased levels of LH cue the ovarian follicle, and you will ovulate about 24 to 36 hours later
    • Once you ovulate (the egg is released), it leaves behind the corpus luteum (the empty follicle)
    • Progesterone released from the corpus luteum after you ovulate will cause a rise in basal body temperature (your temperature when you're fully at rest) of 0.5°F
    • If the egg is not fertilized, your LH levels begin to decline and cause the corpus luteum to begin to shrink and produce less progesterone and estrogen.
    • These low hormone levels cause your body temperature to lower, signal your brain to start the whole cycle over again and trigger the uterine lining to shed—thus begins your next period.

    This first half of your cycle (the follicular stage) can differ greatly for each woman, usually lasting between 14 and 21 days. The second half of your cycle (the luteal phase) typically has a more precise timeline—beginning on the day you ovulate and usually lasting 14 days. It usually does not vary by more than a day in each person.

    The Day You Ovulate

    To determine the answer to: when do you ovulate, you need to count 15 days back from the first day of your period. This is most likely when your LH surge has occurred. Then you can assume that you would have ovulated 1 1/2 days (24 to 36 hours) later. For a 28-day cycle, this would be sometime on Day 14 or 15 (depending on the time the LH surge occurs). Remember: To calculate when you will ovulate, you need to:

    • Count back from Day 1 of your cycle
    • Have reliable cycles that last the same number of days each time
    • Realize that this is not an exact science—many factors, such as stress, illness or disruption of normal routines, can affect or hinder the hormone production required for you to ovulate
    • Understand that not all women will ovulate the same time every month
    • Know that not all women ovulate—especially women who have short menstrual cycles (less than 25 days or longer than 35 days)
    • Remember—you do not ovulate on the pill (or on many forms of hormonal birth control).


    Welt, Corrine K. (2015) "Physiology of the normal menstrual cycle." UpToDate. Accessed February 2017.

    Continue Reading