The Science Behind Changing Period Dates

The Science Behind Changing Period Dates

Published: 10:16AM 15 May 2023

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Jayti Shah

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Menstruation is a natural biological process that occurs in women of reproductive age, typically following a regular cycle. However, changes to period dates can occur due to various factors, sparking curiosity about the science behind these alterations. This blog will delve into the reasons behind changing period dates, shedding light on the complexities of the female reproductive system.

Understanding the Menstrual Cycle

The menstrual cycle, which lasts on average 28 days, is a delicate interplay of hormones, primarily estrogen and progesterone, which regulate the preparation of the uterus for potential pregnancy and the shedding of the uterine lining (menstruation) if pregnancy does not occur.

1. The Follicular Phase

This phase begins on the first day of your period and ends with ovulation. The pituitary gland secretes follicle-stimulating hormone (FSH), stimulating the ovaries to produce about five to 20 small sacs called follicles. Each follicle houses an immature egg.

2. Ovulation

Around mid-cycle, usually on day 14, the luteinizing hormone (LH) surges, triggering the release of the mature egg from the dominant follicle - this is ovulation.

3. The Luteal Phase

After ovulation, the follicle transforms into the corpus luteum, which releases progesterone to thicken the uterine lining for potential implantation. If fertilization doesn't occur, the corpus luteum disintegrates, causing progesterone levels to fall and menstruation to begin.

Factors Influencing Changes in Period Dates

1. Stress

Stress can affect the functioning of the hypothalamus, the part of the brain that regulates hormones controlling the menstrual cycle. This can lead to alterations in period dates.

2. Weight Changes

Extreme weight loss, weight gain, or having a low body weight can cause changes in the menstrual cycle. This occurs because body fat influences the amount of estrogen produced, an essential hormone for regular periods.

3. Exercise

Excessive exercise can lead to changes in menstrual cycle dates due to the energy deficit it creates, leading to hormonal imbalances.

Regulating Period Dates

1. Hormonal Contraceptives

Hormonal contraceptives, such as birth control pills, can be used to regulate menstrual cycles, as they artificially control hormone levels in the body.

2. Lifestyle Changes

Maintaining a healthy weight, managing stress, and engaging in moderate exercise can help regulate period dates by promoting hormonal balance.


Understanding the science behind changing period dates can provide reassurance and guidance on when to seek medical advice. While slight variations in period dates can be considered normal, drastic changes may indicate underlying health conditions that require medical attention. Stay in tune with your body and seek professional advice if you notice significant changes in your menstrual cycle.

Jayti Shah is a Clinical Nutritionist with a master's degree in Clinical Nutrition and Dietetics. She is a member of the Indian Dietetic Association (IDA). Over the last 9 years, she has helped 400 clients in their clinical and weight loss journeys. She works with SocialBoat as a nutrition consultant.

At SocialBoat, we offer custom diet plans and guided workouts to help you achieve your goals in a 360-degree approach. Our gamified experience ensures that you don’t find workouts boring and we reward you for being consistent with your efforts.

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  1. Mayo Clinic. (2019). Menstrual cycle: What's normal, what's not.
  2. American College of Obstetricians and Gynecologists. (2020). Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign.
  3. Nillni,Y. I., Toufexis, D. J., & Rohan, K. J. (2011). Anxiety sensitivity, the menstrual cycle, and panic disorder: a putative neuroendocrine and psychological interaction. Clinical psychology review, 31(7), 1183-1191.
  4. Warren, M. P., & Perlroth, N. E. (2001). The effects of intense exercise on the female reproductive system. The Journal of endocrinology, 170(1), 3-11.
  5. Harris, H. R., Terry, K. L., & Rich-Edwards, J. W. (2019). Long and irregular menstrual cycles, polycystic ovary syndrome, and ovarian cancer risk in a population-based case-control study. International journal of cancer, 144(4), 678-687.
  6. Mayo Clinic. (2019). Birth control pill FAQ: Benefits, risks and choices.
  7. Harlow, S. D., Gass, M., Hall, J. E., Lobo, R., Maki, P., Rebar, R. W., ... & de Villiers, T. J. (2012). Executive summary of the Stages of Reproductive Aging Workshop + 10: addressing the unfinished agenda of staging reproductive aging. Menopause, 19(4), 387

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