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Prenatal factors, childhood growth trajectories and age at menarche
Isabel dos Santos Silva1, Bianca L De Stavola, Vera Mann
1Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK. isabel.silva@lshtm.ac.uk
Insights
Larger birth size may influence the timing of menarche, but this effect is mediated by childhood growth. Early life growth appears to be a key factor in pubertal timing.
Area of Science:
- Pediatric Endocrinology
- Reproductive Health
- Human Growth and Development
Background:
- A larger birth size has been linked to delayed menarche, but the underlying mechanisms remain unclear.
- Birthweight predicts childhood body size, which is associated with earlier menarche onset.
Purpose of the Study:
- To investigate the relationship between birthweight, infant growth, childhood growth trajectories, and the timing of menarche.
- To clarify the mediating role of early childhood growth in the association between birth size and menarche.
Main Methods:
- Utilized data from a British cohort of 2547 girls born in 1946, prospectively followed throughout childhood.
- Employed random coefficients models to estimate height and body mass index (BMI) trajectories up to age 7 years.
- Applied Weibull survival models to analyze the timing of menarche, incorporating birthweight and growth parameters.
Main Results:
- Birthweight positively influenced height and BMI at age 2 but not subsequent growth rates.
- Initial findings showed low birthweight associated with early menarche, but this reversed after controlling for infant growth.
- Rapid infant growth correlated with early pubertal maturation, but these effects diminished when childhood growth (ages 2-7) was considered.
Conclusions:
- The influence of birthweight and infant growth on menarche timing appears to be mediated by early childhood growth.
- Findings suggest that menarche timing may be established in utero or early life but can be modified by childhood body size and composition changes.
Background:
In recent studies a larger birth size has been shown to delay the timing of menarche. The mechanisms underlying this association are not clear, however, as birthweight is a predictor of body size in childhood, and a large body size is known to be associated with an early onset of menarche.
Methods:
Data from a representative British cohort of 2547 girls born in 1946 who were followed prospectively throughout childhood were used. Information was available on prenatal characteristics, birthweight, height, weight and social circumstances during childhood, and on age at menarche. Random coefficients models were used to estimate the individual trajectories in height and body mass index (BMI) up to age 7 years. The parameters identified by these models were then included in Weibull survival models for the timing of menarche together with birthweight.
Results:
Birthweight was found to positively influence height and BMI values at age 2 years, but not to affect their rates of change from age 2 to 7 years. Initial analyses showed low birthweight to be associated with an early onset of menarche, but after controlling for growth in infancy this effect was reversed, with girls who were heavy at birth reaching menarche earlier than others with similar infant growth. Rapid growth in infancy was also related to early pubertal maturation. The effects of birthweight and infant growth disappeared, however, when further controlled for growth from age 2 to 7 years.
Conclusions:
The effects of birthweight and growth in infancy on the timing of menarche seem to be mediated through growth in early childhood. These findings are consistent with the possibility that timing of menarche may be set in utero or early in life, although it may be modified by changes in body size and composition in childhood.