The key difference between ovulatory and anovulatory cycles is that the ovulatory cycle releases an ovum while the anovulatory cycle does not release an ovum.
The menstrual cycle is a series of changes that takes place in the female reproductive system based on different hormone levels to prepare the body for pregnancy. It is a 28-day cycle that occurs every month. The three main hormones that regulate the menstrual cycle are oestrogen, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). Ovulatory and anovulatory cycles are phases of the menstrual cycle and are differentiated by the fact that an ovum is released or not. Both ovulatory and anovulatory cycles take place from day 6 to day 14 of the menstrual cycle.
CONTENTS
1. Overview and Key Difference
2. What is an Ovulatory Cycle
3. What is an Anovulatory Cycle
4. Similarities – Ovulatory and Anovulatory Cycles
5. Ovulatory vs Anovulatory Cycles in Tabular Form
6. Summary – Ovulatory vs Anovulatory Cycles
What is an Ovulatory Cycle?
The ovulatory cycle is a phase of the menstrual cycle where an ovum (egg) is released from the ovaries. It is between the 6th and 14th days of the menstrual cycle. During the ovulatory cycle, the oestrogen level rises, causing the lining of the uterus to increase its size (thickens). Along with oestrogen, another hormone called follicle-stimulating hormone causes the growth of follicles in the ovaries. Between days 10th and 14th, a developing follicle forms a completely matured egg or ovum. Around the 14th day of the menstrual cycle, the level of luteinizing hormone increases, causing the release of an ovum from the ovaries, and this process is called ovulation. This marks the end of the ovulatory cycle. Once the ovum gets released from the ovaries, it follows the luteal phase, where the ovum travels along the fallopian tubes. Hormonal imbalances disrupt the normal functioning of the ovulatory cycle and cause anovulation conditions.
Figure 01: Menstrual Cycle
What is an Anovulatory Cycle?
The anovulatory cycle is a phase of the menstrual cycle where an ovum (egg) is not released from the ovaries. Anovulation is a similar term for this condition. Persistent anovulatory cycles would cause infertility when anovulation takes place for a year or longer. An individual with an anovulatory cycle would still experience bleeding due to the changes in hormone levels. This type of bleeding is withdrawal bleeding, where the uterine wall is shed and released without an ovum.
Causes of the anovulatory cycle include hormonal imbalances (progesterone imbalance, luteinizing hormone imbalance, follicle-stimulating hormone imbalance), use of hormonal birth control, overweight or underweight, stress, polycystic ovarian syndrome, and excessive exercise. The disease diagnosis takes place by medical history and physical exam, reviewing the individual’s menstrual cycle, blood tests, and ultrasound. The anovulatory cycle is treatable through lifestyle changes, stress management, good nutrition, medication to balance hormonal levels, and moderate physical activity.
What are the Similarities Between Ovulatory and Anovulatory Cycles?
- Ovulatory and anovulatory cycles occur in the female reproductive system.
- Moreover, they relate to the menstrual cycle.
- Both ovulatory and anovulatory cycles take place from day 6 – 14 days of the menstrual cycle.
- They depend on hormonal levels.
- Moreover, the hormones that affect both cycles include oestrogens, follicle-stimulating hormones, and luteinizing hormones.
What is the Difference Between Ovulatory and Anovulatory Cycles?
The ovulatory cycle releases an ovum, while the anovulatory cycle does not release an ovum. Thus, this is the key difference between ovulatory and anovulatory cycles. A balanced hormonal level is present during the ovulatory cycle, while an imbalanced hormonal level is present during the anovulatory cycle. Moreover, the ovulatory cycle prepares the body for pregnancy while the anovulatory cycle does not prepare the body for pregnancy.
The below infographic presents the differences between ovulatory and anovulatory cycles in tabular form for side-by-side comparison.
Summary – Ovulatory vs Anovulatory Cycles
The menstrual cycle is a series of changes that takes place in the female reproductive system. It is based on different hormone levels that prepare the body for pregnancy. Ovulatory and anovulatory cycles are phases of the menstrual cycle and differentiate by the fact that an ovum is released or not. An ovum is released during the ovulatory cycle. In contrast, an ovum is not released during the anovulatory cycle. Both ovulatory and anovulatory cycles take place from day 6 to day 14 of the menstrual cycle. They depend on the levels of oestrogen, follicle-stimulating hormones, and luteinizing hormones. So, this summarizes the difference between ovulatory and anovulatory cycles.
Reference:
1. “Anovulatory Cycle: What Is It, Causes, Treatment, and More.” Osmosis.
2. “Normal Menstruation (Monthly Period): Menstrual Cycle & Symptoms.” Cleveland Clinic.
Image Courtesy:
1. “Menstrual Cycle2 en” By Isometrik – Own work (CC BY-SA 3.0) via Commons Wikimedia