National Collaborative Study of Girls Prenatally Diagnosed With Turner Syndrome Karyotypes

This is an observational study which will look at girls who are diagnosed with Turner syndrome before they are born. Girls will be divided into two groups: 1) those diagnosed because of features seen on ultrasound which raised the question of Turner syndrome and 2) those diagnosed incidentally when their mother had an amniocentesis for another reason such as advanced maternal age. No clinical procedures nor interventions will be done as part of this data collection study which will occur for the first 3 to 6 years of the girl's life. The investigators will be looking to see if girls who are diagnosed incidentally have less features of Turner syndrome than those girls who are diagnosed because of fetal ultrasound.