Flutterby™! : XY pregnancy

Report of Fertility in a Woman with a Predominantly 46,XY Karyotype in a Family with Multiple Disorders of Sexual Development

... Of course, it should be noted that the incidence of normal fertile females who have a 46,XY karyotype is not known because it is not routine to check the karyotype in fertile women. ...

Now that we're getting the tools to really measure the biology, we're discovering just how complicated sex and gender are...