Earlier mother's age at menarche predicts rapid infancy growth and childhood obesity

Abstract

Background: Early menarche tends to be preceded by rapid infancy weight gain and is associated with increased childhood and adult obesity risk. As age at menarche is a heritable trait, we hypothesised that age at menarche in the mother may in turn predict her children's early growth and obesity risk.

Methods and findings: We tested associations between mother's age at menarche, mother's adult body size and obesity risk, and her children's growth and obesity risk in 6,009 children from the UK population-based Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort who had growth and fat mass at age 9 y measured by dual-energy X-ray absorptiometry. A subgroup of 914 children also had detailed infancy and childhood growth data. In the mothers, earlier menarche was associated with shorter adult height (by 0.64 cm/y), increased weight (0.92 kg/y), and body mass index (BMI, 0.51 kg/m2/y; all p < 0.001). In contrast, in her children, earlier mother's menarche predicted taller height at 9 y (by 0.41 cm/y) and greater weight (0.80 kg/y), BMI (0.29 kg/m2/y), and fat mass index (0.22 kg/m2/year; all p < 0.001). Children in the earliest mother's menarche quintile (< or =11 y) were more obese than the oldest quintile (> or =15 y) (OR, 2.15, 95% CI 1.46 to 3.17; p < 0.001, adjusted for mother's education and BMI). In the subgroup, children in the earliest quintile showed faster gains in weight (p < 0.001) and height (p < 0.001) only from birth to 2 y, but not from 2 to 9 y (p = 0.3-0.8).

Conclusions: Earlier age at menarche may be a transgenerational marker of a faster growth tempo, characterised by rapid weight gain and growth, particularly during infancy, and leading to taller childhood stature, but likely earlier maturation and therefore shorter adult stature. This growth pattern confers increased childhood and adult obesity risks.

Figure 1. Prevalence of Obesity in Children at Age 9 y, by Mother's Age at Menarche

Data are proportions (± 95% CI) of children with obesity (BMI >97th percentile according to the UK 1990 growth reference [19]) in each quintile of mother's menarche from the whole ALSPAC cohort (boys: p-value for trend = 0.003, n = 2,961; girls: p-value for trend = 0.006, n = 3,048), adjusted for age, mother's education, and also for mother's BMI.

Figure 2. Contrasting Early Postnatal Growth Patterns in Offspring of Mothers with Earlier or Later Menarche

Unadjusted weight SD scores are shown in children grouped by extreme quintiles of their mother's age at menarche. Data are means ± standard error from the Children in Focus subgroup (n = 914).