After registration of newborn twins, which is before the age of 12 months for 89% of the twins, the mother of a twin pair receives the first survey which focuses on conception (spontaneous or otherwise), information from parents themselves (demographics, height, weight), pregnancy (e.g. duration, smoking and drinking behaviors of both parents during pregnancy), birth and health (malformations) of the children shortly after birth. The mother is asked to fill in this survey, and this was done by the biological mother for almost all of surveys with others (stepmother, adoptive mother, some fathers) completing this survey in a small number of families (<0.05%).

Subject age
  • 0 months - 12 months
Time span From 1987-01-01 (ongoing)
Geographic location NL
Dorret I. Boomsma
Vrije Universiteit Amsterdam
YNTR administration
Vrije Universiteit Amsterdam
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