The sex ratio at birth (2)

Area of Science:

• Reproductive biology
• Human genetics
• Environmental health

Background:

• The sex ratio at birth (M/F) is influenced by numerous biological and environmental factors.
• Understanding these influences is crucial for reproductive health research and population studies.

Purpose of the Study:

• To explore diverse factors affecting the sex ratio at birth (M/F).
• To review quantitative and theoretical studies on influences such as holidays, male preference, radiation, seasonality, and environmental factors.

Main Methods:

• Quantitative analysis of holiday effects on M/F in the US.
• Review of literature on male offspring preference, radiation exposure (e.g., Mainz nuclear reactor), seasonality, and toxoplasmosis.
• Theoretical discussion on testosterone's role in M/F and associations with autoimmune diseases and neurodevelopmental conditions.

Main Results:

• Holidays like Thanksgiving, Christmas, and Valentine's Day show a rise in M/F.
• Male offspring preference is a significant global influence on M/F.
• Radiation is identified as a stressor that can increase M/F by culling female fetuses.
• Testosterone is implicated in M/F, autoimmune diseases, autism, gender dysphoria, and non-right-handedness.
• Toxoplasmosis may be a key environmental factor influencing M/F.

Conclusions:

• Multiple factors, including socio-cultural preferences, environmental exposures, and hormonal influences, significantly impact the sex ratio at birth.
• Further research is stimulated by these findings on the complex determinants of M/F.