Androgens and fetal growth

Area of Science:

• Endocrinology
• Human Genetics
• Reproductive Biology

Background:

• Sexual dimorphism in birth weight is a well-documented phenomenon.
• The role of androgens in mediating sex differences during fetal development is not fully elucidated.
• Androgen insensitivity syndrome (AIS) presents a unique model to study androgen action.

Purpose of the Study:

• To investigate the impact of androgen action on fetal growth and birth weight.
• To determine if androgen insensitivity syndrome affects birth weight in 46,XY individuals.
• To test the hypothesis that androgens contribute to the observed sex difference in birth weight.

Main Methods:

• Retrospective analysis of birth weights in a cohort of children with 46,XY karyotype.
• Comparison of birth weights between typically developing males, typically developing females, and individuals with androgen insensitivity syndrome.
• Genetic analysis to confirm mutations in the androgen receptor gene in AIS cases.

Main Results:

• Children with 46,XY karyotype and complete androgen insensitivity syndrome exhibited birth weights comparable to those of girls.
• This finding was observed in cases with both clinically complete AIS and confirmed androgen receptor gene mutations.
• Typically developing boys were heavier than typically developing girls at term birth.

Conclusions:

• Androgen action plays a significant role in establishing the sex difference in birth weight.
• The absence of functional androgen signaling in 46,XY individuals normalizes their birth weight to female ranges.
• These findings strongly support the hypothesis that androgens are a key determinant of sex-specific fetal growth patterns.