Cortisol Rhythm in Twin Infants
Author Information
Author(s): Custodio Rodrigo Jose, Junior Carlos Eduardo Martinelli, Milani Soraya Lopes Sader, Simões Aguinaldo Luis, de Castro Margaret, Moreira Ayrton Custodio
Primary Institution: University of Sao Paulo Ribeirao Preto, Brazil
Hypothesis
This study evaluated the influence of twinning and heritability on the age of emergence of salivary cortisol rhythm in infants.
Conclusion
Salivary circadian rhythm appeared at the same postnatal age in monozygotic and dizygotic twin infants, suggesting a greater environmental than genetic impact.
Supporting Evidence
- The mean age of emergence of salivary cortisol circadian rhythm was similar in MZ and DZ twins.
- Seven pairs showed coincidence of the emergence of cortisol rhythm.
- The heritability index was low, suggesting environmental factors play a larger role.
Takeaway
The study found that twins start producing cortisol in a regular pattern at about the same age, showing that their environment matters more than their genes.
Methodology
A longitudinal study measuring salivary cortisol in 34 infants at various postnatal weeks.
Limitations
The study is limited to the onset of cortisol circadian rhythm and does not account for all physiological aspects.
Participant Demographics
34 newborn infants, including 10 monozygotic and 7 dizygotic twin pairs.
Statistical Information
P-Value
0.02
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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