5-Year-Old Started Puberty at Just 10 Months Old – Now Her Mum Is Considering Freezing Her Eggs

A London mother is considering fertility preservation for her five-year-old daughter after the child began showing signs of puberty at just 10 months old.

Sophie Dumas said she had not realised anything was unusual until a health visitor noticed that her daughter Sienna had enlarged breast tissue. After being referred to paediatric endocrinologists, Sienna underwent hormone testing, X-rays to assess her bone age and an MRI scan.

The tests confirmed that she had central precocious puberty, a condition in which the brain begins sending the hormonal signals that trigger puberty much earlier than expected. Sienna's MRI was clear, meaning doctors did not identify an underlying brain abnormality.

What Is Precocious Puberty?

In girls, puberty typically begins around 10 to 11 years old, although it can normally start from about age 8. Puberty is considered precocious when it begins before age 8 in girls.

Central precocious puberty occurs when the normal hormonal pathway that initiates puberty becomes active too early. In many cases, doctors cannot identify a specific cause, although very early puberty can sometimes be associated with conditions affecting the brain.

Sienna's case was particularly early, with her first signs appearing during infancy.

Without treatment, early puberty can cause children to grow rapidly at first, but their bones may mature sooner than expected. This can result in growth plates closing earlier and potentially reduce final adult height.

How Is Early Puberty Treated?

Sienna receives injections of a gonadotropin-releasing hormone (GnRH) analogue every four weeks to suppress the hormonal signals responsible for puberty.

According to her mother, doctors expect treatment to continue until Sienna is around 11 or 12, although this will depend on her bone age and development.

GnRH treatment can pause the progression of puberty and is used to help preserve growth potential. Cambridge University Hospitals says there is no evidence that treatment for precocious puberty affects fertility in the future. Puberty should also resume after treatment is stopped.

Why Is Her Mum Considering Egg Freezing?

Dumas is now looking into fertility preservation because she worries that Sienna's unusually early puberty could affect her ability to have children in adulthood.

However, egg freezing is not a straightforward option for a five-year-old. Mature egg freezing normally involves stimulating the ovaries with fertility medication before surgically collecting mature eggs. The American Society for Reproductive Medicine describes mature egg freezing as an established fertility-preservation method for post-pubertal females.

For younger children who have not reached puberty, ovarian tissue freezing is the principal fertility-preservation approach. It involves surgically removing and freezing ovarian tissue containing immature eggs for possible future use.

The UK's Human Fertilisation and Embryology Authority (HFEA) also notes that ovarian tissue freezing can be an option for younger people who have not started ovulating.

Importantly, Sienna's mother is considering fertility preservation as a precaution rather than because doctors have told her that her daughter is infertile.

For now, Dumas said she hopes the hormone-blocking treatment will protect Sienna's future fertility while allowing her to continue enjoying childhood.

The family is also dealing with the everyday effects of early hormonal changes. Sienna has developed hormone-related spots and has reportedly faced teasing from classmates who mistook them for chickenpox.

Her mother has urged other parents to seek medical advice if they notice unusual physical changes, even if they initially seem insignificant.