Puberty Timing and Adiposity Change Across Childhood and Adolescence

Disentangling Cause and Consequence

Linda M. O'Keeffe; Monika Frysz; Joshua A. Bell; Laura D. Howe; Abigail Fraser

Disclosures

Hum Reprod. 2020;35(12):2784-2792. 

In This Article

Results

The characteristics of participants included in analyses (N = 4176), by sex, are shown in Table I. Mean aPHV was 11.7 (standard deviation (SD) = 0.8) for females (N = 2186) and 13.6 (SD = 0.9) for males (N = 1990). Findings from linearity tests of aPHV and fat mass at each age demonstrated little evidence of departures from linearity, allowing aPHV to be examined as a continuous exposure (Supplementary Table SV). Mothers of participants included in the analysis were more likely to be married, have higher household social class, higher education, higher partner education, lower prevalence of smoking during pregnancy, lower parity and higher maternal age compared with participants excluded due to missing exposure, outcome or confounder data (Supplementary Table SVI). Participants included in analyses were more likely to be female and higher birth weight compared with those excluded. However, gestational age at birth, maternal BMI, aPHV and fat mass at most occasions were similar between included and excluded participants (Supplementary Table SVI).

Puberty Timing and Adiposity Change From Models by Chronological Age

A 1-year later aPHV in females was associated with a lower fat mass at 9 years (Table II) and faster gain in fat mass from 9 to 18 years. By 18 years, the mean difference per year later aPHV persisted but was smaller. In males, associations were comparable; a 1-year later aPHV was associated with lower fat mass at 9 years which reduced to a smaller difference at age 18 (Table II). Mean-adjusted trajectories of fat mass from 9 to 18 years for the 10th (age 11 in females and age 13 males), 50th (age 12 in females and age 14 in males) and 90th (age 13 in females and age 15 in males) sex-specific percentiles of aPHV by chronological age are presented in Figure 1 Table III.

Figure 1.

Mean trajectories of height-adjusted fat mass in females and males from 9 to 18 years for the 10th, median and 90th sex-specific percentiles of age at peak height velocity from multilevel models based on chronological age. Ages presented are rounded for ease of interpretation. Exact ages are 12.9, 11.7 and 10.7 years for females and 14.7, 13.6 and 12.5 years for males. Age at peak height velocity is normally distributed and median is equal to mean. Models are adjusted for birth weight, gestational age, maternal education, parity, maternal smoking during pregnancy, maternal age, maternal pre-pregnancy BMI, household social class, marital status, partner education and breastfeeding. CI, confidence interval.

Puberty Timing and Adiposity Change From Models by Pubertal Age

Among females, a 1-year later aPHV was associated with a slower gain in fat mass before puberty, a lower fat mass at puberty and faster gain in fat mass after puberty. In males, up to 3 years before puberty, a 1-year later aPHV was associated with slower gains in fat mass, whereas from 3 years before puberty to pubertal onset, a 1-year later aPHV was associated with faster gain in fat mass. At puberty onset, males with a 1-year later aPHV had lower fat mass, albeit with confidence intervals spanning the null value. After puberty, later aPHV was associated with slower gain in fat mass. Mean-adjusted trajectories of fat mass from 9 to 18 years for the 10th (age 11 in females and 13 males), 50th (age 12 in females and 14 in males) and 90th (age 13 in females and 15 in males) sex-specific percentiles of aPHV by pubertal age are presented in Figure 2.

Figure 2.

Mean trajectories of height-adjusted fat mass in females and males from 9 to 18 years for the 10th, median and 90th sex-specific percentiles of age at peak height velocity from multilevel models based on pubertal age. Ages presented are rounded for ease of interpretation. Exact ages are 12.9, 11.7 and 10.7 years for females and 14.7, 13.6 and 12.5 years for males. Age at peak height velocity is normally distributed and median is equal to mean. Models are adjusted for birth weight, gestational age, maternal education, parity, maternal smoking during pregnancy, maternal age, maternal pre-pregnancy BMI, household social class, marital status, partner education and breastfeeding.

Unadjusted and confounder-adjusted results were similar for each analysis (Supplementary Tables SVII and SVIII), regardless of whether unadjusted analyses were performed on N = 5693 participants with data on aPHV and at least one measure of fat mass from 9 to 18 years or on the sample included in our main analysis with complete confounder data too (N = 4176).

Sensitivity Analyses

Estimates of sex-specific associations of aPHV with observed fat mass data at age 9 and 18 years were similar to those obtained from both types of multilevel models (by chronological age and time before and after puberty onset) (Supplementary Table SIX). Results were not appreciably different when analyses were restricted to participants with at least one measure of fat mass before and one measure after aPHV (Supplementary Figures S2 and S3). Results for females were also similar when using self-reported age at menarche rather than aPHV (Supplementary Figure S4). Our analyses were also not appreciably different when restricted to White ALSPAC participants only (Supplementary Figures S5 and S6).

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