The purpose of this study is to determine a threshold value of fetal anogenital distance in 2D ultrasound to differentiate male fetuses from female fetuses, starting 18 weeks of gestation and until the due date.

The study also evaluates the feasibility of the measure and its interobserver variability.

The anogenital distance of female newborns is shorter than that of male newborns.

Urogenital disorders, such as hypospadias and micro-penis, are associated with a shorter anogenital distance.

Anogenital distance is a good marker of fetal exposure to androgenic substances.

Prenatal anogenital distance ultrasound measure can help the diagnosis in case of doubt about fetal sexual phenotype or in case of urogenital disorder suspicion (hypospadias or micropenis).

Is the anogenital distance easy to make measure? Can this procedure be reproduced? What are the threshold values to determine fetal sex at each term of pregnancy?

Inclusion Criteria:

• pregnant woman
• sonographic fetal follow up in Brest Hospital
• term>18 weeks of gestation

Exclusion Criteria:

• No datation between 11 weeks of gestation and 13 weeks of gestation and 6 days by crown-rump length measurement
• Minor
• no consent
• ultrasound performed by an operator without ultrasonography graduation

Pregnant women

All pregnant women follow up at Brest Hospital to 18 weeks of gestation until term, except suspicion of fetal pelvic malformations and patients without an exact echographic datation of pregnancy between 11 and 13+6 weeks of gestation.

All collected data that underlie results in a publication

Data will be available after the publication of result and ending three years maximum following the last visit of the last patient

Data access requests will be reviewed by the internal committee of Brest UH. requestors will be required to sign and complete a data access agreement