XY Female Pregnancy
by M. Italiano
SUCCESSFUL PREGNANCIES IN HUMAN XY FEMALES:
THE XY (and z of) FEMALE CLASSIFICATION
We were taught in grade school that a person's sex is ultimately determined and defined by one's sex chromosomes. If you have an XX chromosome type, your "true sex", is female. If you have an XY chromosome type, your "true sex" is male.
Recent evidence, though, demonstrates that this is far from being the truth(1)
Althoug some people cite XY persons with androgen insensitivity syndrome, who are externally female and have female secondary sexual characteristics, to support a classification of some XY individuals as females,(2)
still, because they have testes and no uterus or tubes, others are not convinced that they should be classified as females, but still classify them as males (3),
or use the term male pseudohermaphrodite. The doing away with sex testing in the Olympics provides insight into the problems of defining sex on the basis of chromosomes.(4)
However, another syndrome, XY gonadal dysgenesis or the XY sex reversal syndrome(1) is convincing enough, to require that even some persons with a normal Y chromosome must be regarded as female.
Why? Because XY human females have been known to give birth.(5,6,7,8)
It is now known that it is not the Y chromosome per se that defines maleness, but it is a complex interaction with X and Y chromosomal genes and gene products with genes and gene products on non sex chromosomes, that defines maleness.(9,10)
In other words, it is XY, plus z(z being a variable of any number of additional circumstances).
A disturbance with any of these genes, or possibly environmental influences, may cause an XY person to become a female with a uterus and ONLY female anatomy, who is capable of giving birth. Although these females have ovarian tissue which degenerates prematurely(11),when they are provided with donor eggs, their giving birth to single pregnancies(5,8), twin pregnancies(6), and even more than one successive pregnancy(7), leaves us with a new indisputable fact: XY can sometimes equal female.
1) Lopez-Lopez, M. (1998) Genetic heterogeneity and phenotypic
variability in 46,XY sex reversal. (Article in Spanish).
Rev. Invest. Clin., Mar-Apr;50(2):171-176.