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Describing differences in weight and length growth trajectories between white and Pakistani infants in the UK: analysis of the Born in Bradford birth cohort study using multilevel linear spline models
  1. Lesley Fairley1,
  2. Emily S Petherick1,
  3. Laura D Howe2,3,
  4. Kate Tilling3,
  5. Noel Cameron4,
  6. Debbie A Lawlor2,3,
  7. Jane West1,
  8. John Wright1
  1. 1Bradford Institute for Health Research, Bradford Teaching Hospitals NHS Foundation Trust, Bradford, UK
  2. 2MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
  3. 3School of Social and Community Medicine, University of Bristol, Bristol, UK
  4. 4Exercise and Health Sciences, School of Sport, Loughborough University, Loughborough, UK
  1. Correspondence to Lesley Fairley, Born in Bradford, Bradford Institute for Health Research, Bradford Teaching Hospitals NHS Foundation Trust, Bradford Royal Infirmary, Duckworth Lane, Bradford BD9 6RJ, UK; Lesley.fairley{at}


Objective To describe the growth pattern from birth to 2 years of UK-born white British and Pakistani infants.

Design Birth cohort.

Setting Bradford, UK.

Participants 314 white British boys, 383 Pakistani boys, 328 white British girls and 409 Pakistani girls.

Main outcome measures Weight and length trajectories based on repeat measurements from birth to 2 years.

Results Linear spline multilevel models for weight and length with knot points at 4 and 9 months fitted the data well. At birth Pakistani boys were 210 g lighter (95% CI −290 to −120) and 0.5 cm shorter (−1.04 to 0.02) and Pakistani girls were 180 g lighter (−260 to −100) and 0.5 cm shorter (−0.91 to −0.03) than white British boys and girls, respectively. Pakistani infants gained length faster than white British infants between 0 and 4 months (+0.3 cm/month (0.1 to 0.5) for boys and +0.4 cm/month (0.2 to 0.6) for girls) and gained more weight per month between 9 and 24 months (+10 g/month (0 to 30) for boys and +30 g/month (20 to 40) for girls). Adjustment for maternal height attenuated ethnic differences in weight and length at birth, but not in postnatal growth. Adjustment for other confounders did not explain differences in any outcomes.

Conclusions Pakistani infants were lighter and had shorter predicted mean length at birth than white British infants, but gained weight and length quicker in infancy. By age 2 years both ethnic groups had similar weight, but Pakistani infants were on average taller than white British infants.

  • Growth
  • Ethnicity
  • Child
  • Born in Bradford
  • Multilevel Models

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