Some basics facts about ovulation that can be helpful when you try to conceive.

What is ovulation?

Ovulation is part of the menstrual cycle.  It occurs when the ovary releases a mature egg.  The released egg travels down the fallopian tube where it may, or may not be fertilized by sperm.

To prepare for a fertilized egg the walls of the uterus thicken.  If fertilized, the egg then implants in the uterus and develops into a pregnancy.  If left unfertilized, the egg disintegrates, and the uterine lining is shed about two weeks later causing menstrual flow to begin.

A woman is the most fertile around the time of ovulation.

When does ovulation occur?

As a rule, ovulation occurs halfway through the menstrual cycle.  This is around day 14 of the average 28-day cycle, counting from the first day of one period to the first day of the next.  Nonetheless, not everyone has a textbook 28-day cycle, so the exact timing varies.  In general, ovulation follows in the 4 days before or the 4 days after the cycle’s midpoint.

The process of ovulation begins with the release of the follicle-stimulating hormone (FSH).  This happens typically between day 6 and day 14 of the menstrual cycle.  FSH helps the egg inside the ovary to mature.

Once the egg is mature, the body releases a surge of luteinizing hormone (LH).  LH triggers the egg’s release.  Ovulation happens in the next 24 to 36 hours and it lasts between 12 and 24 hours.  This is how long the released egg is viable for fertilization.

How do I know when I am ovulating?

Apart from charting the timing on a calendar, other bodily signs indicate that you could be ovulating:

  • A change in vaginal secretions: Looming ovulation can cause an increase in vaginal discharge. This discharge is often clear, stretchy and it may even resemble raw egg whites.  After ovulation the discharge decreases in volume and appears thicker or cloudier.
  • A change in basal body temperature: Keeping track of your body’s basal body temperature for 2 to 3 menstrual cycles may help predict when you are fertile. Take the basal body temperature in the morning before you get out of bed.  Many women show a slight increase in early morning body temperature shortly after ovulating.  A woman is most fertile during the 2 to 3 days before her temperature rises.
  • Increase in LH: About 24 to 36 hours before you ovulate your LH levels increases.  A rise in LH is a signal for the ovary to release an egg.  An ovulation kit can detect this hormone’s increase.  The ovulation kit tests a sample of urine in the days leading up to ovulation and a rise in LH will show a positive result.

If you menstruate, it does not mean that you ovulate.

It is not true that if you menstruate, you ovulate.  If a woman gets her period on a monthly basis, but she is not becoming pregnant, it may be because she is not ovulating.  An ovulation kit can be helpful to determine whether a woman is in fact ovulating or not.  It is best to check with your healthcare practitioner should the test indicate that ovulation is not occurring.

Why am I not ovulating?

There are many reasons why a woman may have ovulation problems:

  • Blocked fallopian tubes: This may be due to pelvic inflammatory disease, endometriosis or surgery for an ectopic pregnancy.
  • An abnormal level of hormones can cause ovulation to be irregular or not occur at all: E.g., polycystic ovary syndrome (PCOS). Thyroid problems can also make the ovaries less likely to release an egg.
  • Weight: A woman who is underweight with a body mass index (BMI) of 18.5 or less may have irregular menstrual cycles. This could also cause ovulation to stop.  Obesity can lead to irregular periods and irregular ovulation.
  • Stress and excessive exercise can influence the timing of ovulation: Emotional or physical stress may delay ovulation or prevent a woman from ovulating. Getting too much or intense physical activity can also inhibit ovulation.

Problems with ovulation are just one possible cause for infertility.  Please consult your healthcare practitioner should you have any concerns.