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Associations of Birth Order with Early Adolescent Growth, Pubertal Onset, Blood Pressure and Size: Evidence from Hong Kong's "Children of 1997" Birth Cohort.

Kwok MK, Leung GM, Schooling CM - PLoS ONE (2016)

Bottom Line: Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income.Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

ABSTRACT

Background: Birth order has been proposed as a cardiovascular risk factor, because the lower birth weight and greater infant weight gain typical of firstborns could programme metabolism detrimentally.

Methods: We examined the associations of birth order (firstborn or laterborn) with birth weight-for-gestational age, length/height and body mass index (BMI) z-scores during infancy, childhood, and puberty using generalized estimating equations, with age at pubertal onset using interval-censored regression and with age-, sex- and height-standardized blood pressure, height and BMI z-scores at 13 years using linear regression in a population-representative Chinese birth cohort: "Children of 1997" (n = 8,327).

Results: Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income. Firstborns had earlier onset of pubic hair (time ratio = 0.988, 95% CI 0.980, 0.996), but not breast or genitalia, development. Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.

Conclusions: Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

No MeSH data available.


Related in: MedlinePlus

Length/height and body mass index (BMI) growth curves from birth to 14 years by birth order in the Hong Kong’s “Children of 1997” birth cohort, Hong Kong, China, 1997–2010.
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pone.0153787.g001: Length/height and body mass index (BMI) growth curves from birth to 14 years by birth order in the Hong Kong’s “Children of 1997” birth cohort, Hong Kong, China, 1997–2010.

Mentions: Table 2 shows that compared with laterborns, firstborns had lower birth weight-for-gestational age, after adjusting for sex, parental age, birthplace, education and household income. During infancy, firstborns had lower BMI z-score. During childhood, firstborns had greater height and BMI z-scores. During puberty, firstborns had greater height, but not BMI, z-score. Compared with laterborns, firstborns had earlier age at onset of pubic hair development, but not age at onset of breast or genitalia development, after adjusting for sex, parental age, birthplace, education and household income. At ~13 years, firstborns had greater BMI, but not height, z-score, and similar systolic or diastolic blood pressure z-score. The available case analysis produced similar patterns, except the association of birth order with BMI z-scores at 13 years was not statistically significant (S1 Table). Fig 1 shows compared with laterborns, firstborns had similar length/height from early infancy, but lower BMI until about ~3 years after which they had higher BMI than laterborns.


Associations of Birth Order with Early Adolescent Growth, Pubertal Onset, Blood Pressure and Size: Evidence from Hong Kong's "Children of 1997" Birth Cohort.

Kwok MK, Leung GM, Schooling CM - PLoS ONE (2016)

Length/height and body mass index (BMI) growth curves from birth to 14 years by birth order in the Hong Kong’s “Children of 1997” birth cohort, Hong Kong, China, 1997–2010.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835083&req=5

pone.0153787.g001: Length/height and body mass index (BMI) growth curves from birth to 14 years by birth order in the Hong Kong’s “Children of 1997” birth cohort, Hong Kong, China, 1997–2010.
Mentions: Table 2 shows that compared with laterborns, firstborns had lower birth weight-for-gestational age, after adjusting for sex, parental age, birthplace, education and household income. During infancy, firstborns had lower BMI z-score. During childhood, firstborns had greater height and BMI z-scores. During puberty, firstborns had greater height, but not BMI, z-score. Compared with laterborns, firstborns had earlier age at onset of pubic hair development, but not age at onset of breast or genitalia development, after adjusting for sex, parental age, birthplace, education and household income. At ~13 years, firstborns had greater BMI, but not height, z-score, and similar systolic or diastolic blood pressure z-score. The available case analysis produced similar patterns, except the association of birth order with BMI z-scores at 13 years was not statistically significant (S1 Table). Fig 1 shows compared with laterborns, firstborns had similar length/height from early infancy, but lower BMI until about ~3 years after which they had higher BMI than laterborns.

Bottom Line: Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income.Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

ABSTRACT

Background: Birth order has been proposed as a cardiovascular risk factor, because the lower birth weight and greater infant weight gain typical of firstborns could programme metabolism detrimentally.

Methods: We examined the associations of birth order (firstborn or laterborn) with birth weight-for-gestational age, length/height and body mass index (BMI) z-scores during infancy, childhood, and puberty using generalized estimating equations, with age at pubertal onset using interval-censored regression and with age-, sex- and height-standardized blood pressure, height and BMI z-scores at 13 years using linear regression in a population-representative Chinese birth cohort: "Children of 1997" (n = 8,327).

Results: Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income. Firstborns had earlier onset of pubic hair (time ratio = 0.988, 95% CI 0.980, 0.996), but not breast or genitalia, development. Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.

Conclusions: Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

No MeSH data available.


Related in: MedlinePlus