The influence of birthweight and breastfeeding status on BMI outcome at first year of primary school: a retrospective study of an Irish child cohort

Recent data shows one in four children in Ireland are classified as having overweight or obesity, putting them at increased risk of health complications in both childhood and adulthood. The primary aim of this study was to retrospectively investigate the association between body mass index (BMI) outcome at first year of primary school and sex, birthweight and breastfeeding status in a cohort of Irish children. A secondary aim was to assess whether parents were concerned about their child’s growth. This study examined data from the National Child Health Screening Programme on 3739 children in their first year of primary school education in the Irish counties of Sligo, Leitrim and Donegal. This data was collected between March 2013 and December 2016. 10.8% and 7.1% of the children included in this study were classified as having overweight and obese BMI outcomes, respectively. A greater proportion of males had underweight, overweight or obese BMI outcomes compared to females, and this was statistically significant (p ≤ 0.001). Overweight and obese BMI outcomes were significantly more common among those born with a high birthweight, compared to those with a low or healthy birthweight (p ≤ 0.001). There was a greater proportion of obese BMI outcome in those who were never breastfed compared to those who were ever breastfed, and this difference was statistically significant (p = 0.041). Among those who were ever breastfed, there was a statically significant (p = 0.009) difference between BMI outcome at first year of primary schooling and the duration of time they were breastfed for. When asked whether they were concerned about their child’s growth, the majority of parents who responded expressed no concern (96.1%). Conclusion: This study found an association between BMI outcome at first year of primary school education and sex, birthweight and breastfeeding status in a cohort of children in the North-West of Ireland. The majority of parents did not express concern related to their child’s growth at first year of primary education.What is Known:• One in every four children in Ireland are classified as having overweight or obesity.• Birthweight and breastfeeding status are factors known to be associated with weight status in childhood.What is New:• This study investigated whether there was an association between sex, birthweight and breastfeeding status and the BMI outcome of a cohort of Irish children in their first year of primary school education (median age: 5.2 years).• This study also included an exploration of parents concern related to their child’s growth at first year of primary school education.