Birth Control: What It Does, How It Works, and What It Means for Performance

Period Talk⏤Part 3 of collaboration with Jessica Beal, PharmD 

Birth control is a powerful tool for managing one’s reproductive health. It is commonly used to prevent pregnancy, allowing athletes to focus on their sporting careers while maintaining control over family planning. However, navigating the range of birth control options can feel overwhelming. While most people are familiar with how condoms work, choosing methods like the pill, the ring, an IUD, or the patch can feel like placing a lot of trust in science, with your fertility and peace of mind. Gaining a clear understanding of how these methods work can empower us to make informed and confident decisions.

So let’s break it down.

An estimated 65% of women aged 15–49 use birth control, and there are many types available, each working a bit differently, but all aim to prevent an egg and sperm from meeting. Please enjoy my sports analogy!

To understand how hormonal contraceptives work, let’s go back to the basics:

Your hypothalamus and pituitary gland are the control centers in your brain. They send signals via follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to your ovaries to prepare and release an egg. This sets your entire menstrual cycle in motion. If no fertilization occurs, hormone levels drop, and your period begins, starting the cycle again.

Birth control methods that use synthetic hormones (estrogen and/or progestin) disrupt this feedback loop in very specific ways.

Hormonal Birth Control Methods: How They Work

1. Combined Oral Contraceptive Pill (The Pill)

Contains both estrogen and progestin. It prevents ovulation by tricking your brain into thinking you’ve already ovulated. No egg = no fertilization. But you do still bleed, but this is just a hormonal withdrawal bleed, not a true period. 

Note: Side effects can include nutrient depletion, mood changes, bloating, breast tenderness, and altered libido. Different progestins may cause different symptoms in individuals.

2. Progestin-Only Pill (“Mini-Pill”)

No estrogen here, just progestin. It works mainly by thickening cervical mucus, creating a barrier that sperm can’t easily penetrate. It may not reliably stop ovulation, so it must be taken at the same time every day for maximum effectiveness (if your a busy athlete or traveling time zones, this will need to be considered). 

Note: Often preferred by breastfeeding women or those who can’t tolerate estrogen.

3. The Patch

Delivers estrogen and progestin through the skin. Worn on the body for 3 weeks, off for one week. It prevents ovulation and thickens cervical mucus.

Note: Skin irritation and an increased risk of blood clots are potential side effects.

4. The Ring (e.g., NuvaRing )

A flexible ring inserted vaginally that slowly releases hormones locally. It's worn for three weeks, removed for one. Like the patch and pill, it prevents ovulation and thickens cervical mucus.

5. Hormonal Injection (Depo-Provera / Medroxyprogesterone Acetate)

This progestin-only injection is given every 3 months. It stops ovulation, thickens cervical mucus, and thins the uterine lining.

Note: Weight gain is a common side effect due to fluid retention and androgen-like activity. It has been associated with reduced bone mineral density, especially in younger users or those using it long-term, raising concerns about stress fracture risk. Menstrual irregularities are also typical.

5. Hormonal IUDs (e.g., Mirena, Kyleena)

Placed in the uterus, these devices release progestin over several years. They may prevent ovulation, but primarily thicken cervical mucus and thin the uterine lining, making it difficult for sperm to reach or implant an egg.

Note: Some women stop having periods altogether, while others may have irregular spotting at first.

6. Copper IUD (non-hormonal)

Releases copper ions, which are toxic to sperm. It doesn’t impact ovulation or hormone levels but prevents fertilization. 

Note: No hormonal side effects and least likely to impact your natural hormones, but periods may become heavier or more painful initially.

7. Barrier Methods

Condoms, diaphragms, and cervical caps. These physically block sperm from reaching the egg.

Note: No hormonal interference, but less effective if not used correctly every time.

UC Davis

What About Athletes and Performance?

Research on the impact of hormonal birth control on athletic performance is limited, especially beyond the combined oral contraceptive pill (OCP). Here's what we do know:

• OCPs can flatten natural hormonal fluctuations, which may reduce symptoms like PMS, but also remove performance-enhancing benefits of estrogen spikes (e.g., improved neuromuscular coordination, power, and recovery).

• Some athletes on the pill report reduced VO₂ max, while others feel no change or even improved cycle consistency and symptom relief.

• Progesterone-dominant methods (like progestin-only pills and hormonal IUDs) may lead to fatigue, mood changes, or increased core temperature, but again, this varies widely by individual and the formulation used.

• Non-hormonal options like the copper IUD may preserve natural hormonal rhythm, which some high-performing athletes prefer.

The key? There is no one-size-fits-all answer. Every athlete responds differently to each method, and it can take some trial and error (and monitoring) to find what works best for your body, training demands, and long-term health.

Contraceptives aren’t just about avoiding pregnancy; they’re tools that can help or hinder performance, recovery, and overall well-being, depending on how your body responds. It’s essential to work with a healthcare professional who understands both your reproductive goals and your training lifestyle. Sometimes it can be helpful to work with an OBGYN who works predominantly in the athlete population or was an athlete themselves. There is a sense of relatedness and understanding when working with a provider who can value your performance goals and provide you with the best care possible. 

Resources

1. Association of Reproductive Health Professionals. Quick Reference Guide for Clinicians: Choosing a Combined Oral Contraceptive Pill. https://www.arhp.org/uploadDocs/choosingqrg.pdf. Published 2008

2. Bradley SEK, et al., Effectiveness, safety, and comparative side effects. In: Cason P, Cwiak C, Edelment A, et al. [Eds.] Contraceptive Technology. 22nd edition. Burlington, MA: Jones-Bartlett Learning, 2023.

3. Daniels K, Abma JC. Current contraceptive status among women aged 15–49: United States, 2017–2019. NCHS Data Brief, no 388. Hyattsville, MD: National Center for Health Statistics. 2020.

4. Glenner-Frandsen A, With C, Gunnarsson TP, Hostrup M. The Effect of Monophasic Oral Contraceptives on Muscle Strength and Markers of Recovery After Exercise-Induced Muscle Damage: A Systematic Review. Sports Health. 2023 May;15(3):318-327. doi: 10.1177/19417381221121653. Epub 2022 Sep 25. PMID: 36154748; PMCID: PMC10170231.

5. Kayser, B. (2023). Where sports performance meets reproductive rights: hormonal contraception. Drugs: Education, Prevention and Policy, 31(4), 396–402. https://doi.org/10.1080/09687637.2023.2261614

6. Lebrun CM. The effect of the phase of the menstrual cycle and the birth control pill on athletic performance. Clin Sports Med. 1994 Apr;13(2):419-41. PMID: 8013042

7. Rechichi C, Dawson B, Goodman C. Athletic performance and the oral contraceptive. Int J Sports Physiol Perform. 2009 Jun;4(2):151-62. doi: 10.1123/ijspp.4.2.151. PMID: 19567919.

8. Redman LM, Weatherby RP. Measuring performance during the menstrual cycle: a model using oral contraceptives. Med Sci Sports Exerc. 2004 Jan;36(1):130-6. doi: 10.1249/01.MSS.0000106181.52102.99. PMID: 14707778.

9. Seidman L, Seidman DS, Constantini NW. Hormonal contraception for female athletes presents special needs and concerns. Eur J Contracept Reprod Health Care. 2024 Feb;29(1):8-14. doi: 10.1080/13625187.2023.2287960. Epub 2024 Feb 1. PMID: 38108091.

10. Thompson B, Almarjawi A, Sculley D, Janse de Jonge X. The Effect of the Menstrual Cycle and Oral Contraceptives on Acute Responses and Chronic Adaptations to Resistance Training: A Systematic Review of the Literature. Sports Med. 2020 Jan;50(1):171-185. doi: 10.1007/s40279-019-01219-1. PMID: 31677121

    
    

    About the Authors

    

    Jourdan Delacruz is a 2X Olympian and represented Team USA in the sport of Weightlifting at the 2020 and 2024 Olympic Games. Jourdan holds a bachelor's in nutrition and dietetics from the University of Northern Colorado. She is pursuing her master's degree in sports nutrition to become a sport-registered dietitian. Jourdan founded Herathlete, a brand committed to supporting female athletes through education and community.

    

    Jessica Beal-Stahl, PharmD, is a clinical sports pharmacist and the founder of The Athlete’s Pharmacist. She specializes in female athletes, optimizing hormones, and understanding medication impacts on performance. Consulting with athletes, teams, and healthcare providers, Jessica takes an integrative approach, ensuring no foundational aspect is overlooked in pursuit of peak performance and well-being.

    
    

    You can connect with Jess on Instagram @jess_rx or through email at jbealrx@gmail.com

    Be sure to check out her services and offerings at www.theathletespharmacist.com