[Reproductive behavior and Down syndrome]

Area of Science:

• Reproductive biology
• Human genetics
• Developmental disorders

Background:

• Down syndrome (DS) is a genetic disorder caused by trisomy 21.
• Parental factors, including sexual behavior, are being investigated for their potential role in DS etiology.
• Previous research has not conclusively linked parental sexual activity to the occurrence of DS.

Purpose of the Study:

• To investigate the relationship between coital rates, contraception practices, and the incidence of Down syndrome.
• To explore potential links between parental sexual behavior and maternal hormonal dysfunction.
• To examine the sex ratio of children with DS in relation to parental sexual activity.

Main Methods:

• A comparative study involving mothers of 160 newborns with DS and 160 mothers of healthy newborns of similar age.
• Data collection on coital rates and contraception practices.
• Analysis of the sex ratio (SR) in relation to parental sexual activity.

Main Results:

• Parents of children with DS exhibited significantly lower sexual activity compared to control groups.
• No correlation was found between parental sexual behavior and maternal hormonal dysfunction.
• A higher prevalence of boys (SR = 1.85) was observed in the DS group from sexually active couples.

Conclusions:

• Reduced sexual activity is common in parents of children with DS.
• High coital rates may be associated with increased risk of chromosome malsegregation during spermatogenesis.
• These findings suggest a potential link between sexual activity and the occurrence of Down syndrome, particularly the male excess observed in affected newborns.