What is ovulation?
Written by Dr. Specialist Stine Andreassen
Specialist in Gynecology and Obstetrics, PhD in Obstetrics in 2015 and more than 15 years of clinical practice in Obstetrics and Gynecology
Ovulation is the process where one of your ovaries releases an egg.
Each month, your brain and ovaries communicate through hormones in a carefully coordinated cycle:
The brain releases a hormone (FSH) that stimulates the ovaries.
Several small follicles (fluid-filled sacs) begin to mature in the ovary.
Usually, one follicle becomes dominant and prepares to release an egg.
A surge of another hormone (LH) triggers ovulation.
The ovary releases the egg into the fallopian tube.
The egg survives for about 12–24 hours. If sperm is present, fertilization may occur. If not, the egg dissolves naturally.
Why do we get menstruation?
Menstruation happens when pregnancy does not occur. After ovulation, the body produces progesterone, a hormone that prepares the lining of the uterus (the endometrium) for a possible pregnancy.
If the egg is not fertilized hormone levels fall, the thickened uterine lining is no longer needed and the lining sheds. This shedding is your menstrual bleeding.
A period is therefore the body’s way of “resetting” for a new cycle.
What is the reason for irregular menstrual bleedings?
Menstrual irregularities are most often caused by changes or imbalances in hormones. The menstrual cycle is controlled by a delicate hormonal system involving the brain and the ovaries. If this hormonal balance is disrupted, the cycle can change.
Common hormonal causes of menstrual irregularities include:
Irregular or absent ovulation
PCOS (polycystic ovary syndrome)
Thyroid disorders
Stress (which affects hormone signaling from the brain)
Significant weight changes
Perimenopause
When ovulation does not occur regularly, progesterone is not produced in the normal way. This can lead to irregular bleeding, heavy periods, long cycles or missed periods.
Can hormonal contraception affect menstrual bleeding?
Yes. Hormonal contraception changes your natural hormone cycle on purpose. Most hormonal contraceptives work by preventing ovulation, thinning the lining of the uterus and/or changing cervical mucus. Because they alter your natural cycle, they can also change your bleeding pattern. Depending on the method, you may experience lighter periods, irregular spotting, no bleeding at all or scheduled withdrawal bleeding.
Do I need to have a monthly bleed while using contraception?
No, you do not medically need to have a monthly bleed while on hormonal contraception. The bleeding that occurs during the pill’s “break week” is not a natural period. It is called a withdrawal bleed, triggered by a temporary drop in hormones. With many modern contraceptive methods, it is completely safe to skip the hormone-free interval. Not having a monthly bleed while on hormonal contraception is not harmful.
Will I have a reduced chance of becoming pregnant in the future if I use contraception?
For most women, no. Hormonal contraception does not reduce long-term fertility. After stopping contraception ovulation usually resumes within weeks to months. Some women conceive immediately, while for others, it may take some cycles. The return to fertility depends more on age and overall health than on past contraceptive use.