Babies are usually typically born with female or male genitalia but only around 98.2-98.3% are.
A small percentage, about 1.7%, are born "intersex" that is with atypical genitalia where external genitalia appear mixed or not clearly developed. This can cause a challenge as to which sex to register the birth. Later the person may undergo surgery to correct this. They may also wish to identify as the opposite sex to that originally registered at birth.
It is worth noting this 1.7% figure of interest sex births and the 0.54% figure of the population that identifies as transgender.
There are also birth variations- ie Androgen Insensitivity Syndrome, AIS, where the baby is born with XY chromosomes but develop entirely female external genitalia. Female sex may be registered at birth, yet the chromosome make up
Census facts- According to the 2021 last Census, 262,000 people, that is 0.54% of the population aged 16 or over, identified as having a gender identity different from their sex registered at birth. The ONS considers this was an over estimation because of bias in the results, noting that some individuals with a lower proficiency of English may have mistakenly answered that they were trans as a result of misunderstanding of the question wording.
Of that 0.54% 0.10% identified as a trans woman, a very low proportion of the population.
It is not immutable fact that 100% of babies are born with typical male or female genitialia, though around 98.3% are.
We can as a society accommodate appropriate toilet and changing facilities for this small proportion of transgender people I would suggest.
Society needs to treat intersex and AIS born babies as they would treat any other human baby no matter what sex they were register at birth. As people's medical history is private and confidential, a proportion of those 1.7% of babies born intersex, and those born with AIS may now identify as transgender and not their registered birth sex.