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Birth size and age at menarche: a twin perspective
Kaspar Sørensen1, Anders Juul, Kaare Christensen
1Department of Growth and Reproduction GR, Copenhagen University Hospital, Rigshospitalet Section 5064, Blegdamsvej 9, Copenhagen Ø DK-2100, Denmark.
Human Reproduction (Oxford, England)
|August 9, 2013
Summary
Birthweight for gestational age (BW-SDS) was linked to earlier age at menarche in twin girls. However, this association was not significant within twin pairs, suggesting shared genetic or environmental influences.
Area of Science:
- Reproductive Endocrinology
- Twin Studies
- Developmental Biology
Background:
- Nutritional deprivation impacts long-term health.
- Small birth size is linked to early menarche in singletons.
- Genetics and environment's role in this link is unclear.
Purpose of the Study:
- To investigate if birthweight (BW) and co-twin sex affect age at menarche in twins.
- To explore the influence of genetics and shared environment on the BW-menarche association.
Main Methods:
- Cohort study of 2505 twin pairs from the Danish Twin Register.
- Data collected via questionnaires and the Danish Medical Birth Register.
- Birthweight for gestational age standard deviation score (BW-SDS) calculated.
Main Results:
- BW-SDS, not BW, was associated with age at menarche in all twins (HR 0.96).
- No association found between BW-SDS and menarcheal age within twin pairs (HR 1.01).
- Heritability estimates for menarcheal age and BW were 0.61 and 0.27, respectively.
Conclusions:
- Lower BW for GA is associated with earlier menarche in twin girls.
- Shared genetic/environmental factors, not within-pair intrauterine differences, govern this association.
- Findings suggest shared factors influence menarche timing, with limitations including recall bias.
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