Do natural hormone levels matter in sports?

Controversy erupted after Italian boxer Angela Carini, Imane's opponent, forfeited a match "in fear for my life," claiming she had never been punched so hard in her career.

Two major sports organizations held conflicting opinions on Khelif's eligibility. The International Olympic Committee (IOC) affirmed that Imane Khelif was born a woman, registered as a woman, held a woman's passport, and lived her life as a woman. However, the International Boxing Association (IBA) stated that Imane and another boxer, Taiwan's Lin Yu-ting, were ineligible to participate in the Women's World Boxing Championship 2023 because they "did not meet one of the criteria." Umar Kremlev, president of the IBA, said these two women have XY chromosomes.

The news divided the public. As a doctor, I find this debate significant as it raises awareness that determining one's gender isn't always clear-cut.

People often perceive gender as binary: male or female. Men speak loudly, women whisper. Gender can manifest outwardly through sexual orientation and social interactions.

Ancient Chinese philosophy views males and females as "yang" and "yin." Harmony between "yin" and "yang" brings prosperity.

However, appearances alone cannot determine gender. Some men are meek, and some women are strong.

Biologically, researchers have identified specific sex hormones. Testosterone, known as the male hormone, is produced in the testicles and contributes to muscle development and hair growth. Estrogen, the female hormone, is produced in the ovaries and contributes to feminine characteristics, including childbearing.

At first glance, determining gender seems simple: those with testosterone are men, and those with estrogen are women. However, women produce small amounts of testosterone in their adrenal glands, while men produce small amounts of estrogen in their testicles and adipose tissues. Depending on hormone levels, individuals can appear "feminized" or "masculinized."

Hormones alone do not determine gender. At a molecular level, scientists discovered sex chromosomes. Each person has 22 pairs of normal chromosomes and a pair of sex chromosomes. Females have XX chromosomes, while males have XY chromosomes.

During fertilization, the mother's egg cell always carries an X chromosome, while the father's sperm cell carries either an X or Y chromosome. The combination determines if a baby is biologically male or female.

However, XX chromosomes alone don't make someone female, and XY chromosomes alone don't make someone male. Embryo development in the womb also plays a role.

In the first seven weeks, the embryo has no sex-specific characteristics. Under gene influence, testicles form first, producing testosterone, which transforms reproductive organs into male ones.

However, there are cases where XX chromosomes are present, but during development, an excess of male hormones results in male reproductive organs.

Numerous chromosomal and genetic disorders affect sexual development. In November 2005, the Chicago Consensus agreed on the term "Disorders of Sex Development" to replace terms like intersex, hermaphroditism, and pseudohermaphroditism. These disorders are congenital conditions where the development of chromosomal, gonadal, or anatomical sex is atypical. The incidence of these disorders can be 1 in 1,000 within a community.

Being a man or a woman involves biological characteristics and socio-cultural environment. As science advances, people can view issues from multiple angles.

A person with XY chromosomes but born with female genitalia would be raised as a girl, growing up knowing they are a girl, despite high testosterone levels. In sports, should chromosomes or appearances and mindset dictate gender?

This is why two major sports organizations are steadfast in their decisions, as they approach the question from different viewpoints. People can see this matter differently as well.

The world is wide and complex, not always black and white. While men and women can have male and female characteristics, sports need clear sex distinctions. Women athletes cannot compete in male categories and vice versa.

Therefore, I support the IBA's decision to ensure sports equality. Testosterone has long been a doping substance due to its ability to increase muscle mass, strength, and stamina. Its use is banned in sports. However, some people may have higher levels of testosterone due to mutations, contributing to better sports performance with possibly less training, which is unfair. To ensure equality, I believe sporting competitions should consider both gender and hormone levels.

*Doctor Quan The Dan is deputy director of Tri Duc Thanh General Hospital in Thanh Hoa Province in central Vietnam.