January 6, 2025

Cervical Health Awareness Month

The Central Role of the Cervix in Fertility: A Review

By: Kaitlin Potter

Editor’s Note: During the first two weeks of Cervical Health Awareness Month, we will consider the significance of the cervix on fertility and women’s health. With its central role in reproduction, cervical fluid is truly the elixir of life. Martyn et al explored this topic in the article, “The Role of the Cervix in Fertility: Is It Time for a Reappraisal?” [1] It was published in 2014 in Human Reproduction and summarized below by Kaitlin Potter, a student in the online elective developed and taught by FACTS through Georgetown University School of Medicine. The authors present their argument supporting the need to revisit the role of the cervix in fertility given the insights gained over the last several decades about this gate to the womb.

 

Introduction

The cervix, traditionally seen as a passive structure in the reproductive system, is a critical gateway between the vagina and uterus. In the context of fertility, the cervix has often been underappreciated, with most research and clinical attention focused on the ovaries, fallopian tubes, and uterus. The article [1] by Martyn, McAuliffe, and Wingfield summarized below advocates for a reevaluation of the cervix’s role in fertility, highlighting its dynamic functions and potential contributions to both successful conception and unexplained infertility.

Anatomy and Physiology of the Cervix

The cervix is a complex structure composed of connective tissue, smooth muscle, and a canal lined with glandular epithelium. The glandular epithelium produces cervical fluid, also known as cervical mucus, which undergoes cyclical changes in response to hormonal fluctuations during the ovarian-menstrual cycle. This cervical fluid plays a pivotal role in the reproductive process by facilitating or inhibiting sperm transport.

Cervical mucus is thin and watery around the time of ovulation, allowing sperm to penetrate. Its biochemical composition is crucial, as it not only serves as a medium for sperm transport but also acts as a selective barrier, allowing only the most motile and morphologically normal sperm to pass into the uterus. This selection process is critical to ensure any sperm that reach the egg are capable of successful fertilization.

“Cervical mucus … not only serves as a medium for sperm transport but also acts as a selective barrier, allowing only the most motile and morphologically normal sperm to pass into the uterus.”

Cervical Mucus and Fertility

The article by Martyn et al evaluates the complex interaction between cervical mucus and sperm. Although it is not precisely understood yet, the studies presented describe the multiple chemical interactions required for sperm to successfully reach and break through the ovum. This knowledge supports the call for more studies on this process as it relates to fertility.

The authors discuss various ways in which cervical dysfunction can lead to infertility. They examined the impact of human papillomavirus (HPV) infection and its treatment on cervical health. While treatments such as large loop excision of the transformation zone (LLETZ) are effective to remove precancerous cells, they may also cause scarring and cervical stenosis (where the cervical canal is abnormally narrow or completely closed, preventing sperm from entering the uterus). Both scarring and cervical stenosis may harm fertility.

Chronic cervicitis—inflammation of the cervix—may affect fertility by altering the production and composition of cervical mucus. Inflammatory changes can make cervical mucus hostile to sperm, hindering their transport. This is another area that is not well researched but could be very informative to aid patients conceive naturally.

“Chronic cervicitis … may affect fertility by altering the production and composition of cervical mucus. (It) can make cervical mucus hostile to sperm, hindering their transport.”

It is common practice to bypass cervical mucus altogether via in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), or intrauterine insemination (IUI). However, this is not a viable option for everyone and may not lead to optimal outcomes due to the critical role cervical fluid plays in selecting the highest quality sperm. Many people are also opposed to these treatments for ethical or financial reasons. Research into cervical mucus-sperm interaction could lead to new and better treatment options for all patients with infertility.

Beautiful young couple in love walking outdoors at the city street, hugging

Clinical Implications and Future Directions

Based on their review of the literature, the authors propose several clinical recommendations. They advocate for more comprehensive assessments of cervical factors during infertility evaluations. This could include more detailed analysis of cervical mucus quality and quantity as well as assessments of cervical anatomy and function. By improving diagnostic techniques for cervical factors, clinicians may be able to identify previously undetected root causes of infertility.

Furthermore, the authors suggest that treatments targeting cervical dysfunction could be developed or refined. For example, therapies aimed at improving cervical mucus quality, such as hormonal treatments or localized therapies, could benefit women with cervical factor infertility. Additionally, surgical interventions for cervical stenosis or scarring could be optimized to reduce their impact on fertility.

The authors highlight the need for further research into the role of the cervix in fertility. Although some studies have explored the cervix’s role in sperm transport and selection, more research is needed to fully understand its contribution to both normal fertility and infertility. This could include studies on the molecular composition of cervical mucus, the impact of various medical conditions on cervical function, and the long-term effects of cervical treatments on fertility.

“Although some studies have explored the cervix’s role in sperm transport and selection, more research is needed to fully understand its contribution to both normal fertility and infertility.”

Conclusion

Martyn, McAuliffe, and Wingfield make a compelling case for reappraising the role of the cervix in fertility. While often overlooked, the cervix plays a crucial role in sperm transport and survival. Dysfunctions of the cervix, whether due to anatomical abnormalities, infections, or alterations in mucus production, can have significant impact on fertility. The authors argue that by focusing more attention on the cervix during infertility evaluations, clinicians may be able to uncover hidden causes of infertility, particularly in cases of unexplained infertility. This reappraisal could lead to more comprehensive fertility assessments and better outcomes for patients with infertility.

References

[1] Martyn F, McAuliffe FM, Wingfield M. The role of the cervix in fertility: is it time for a reappraisal?. Hum Reprod. 2014;29(10):2092-2098. doi:10.1093/humrep/deu195

ABOUT THE AUTHOR

Kaitlin Potter

Kaitlin Potter is a third-year medical student at Marian University Wood College of Osteopathic Medicine in Indianapolis, IN. She completed her undergraduate education at Pensacola Christian College in Pensacola, FL. She is interested in obstetrics and gynecology, pediatrics, and a holistic approach to medicine. She enrolled in the FACTS elective to gain a better understanding of natural family planning methods to offer her future patients more options outside of pills, devices, and injections.

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