Exclusive breastfeeding and infant growth studies: reference standards for head circumference, length and mid-arm circumference/head circumference ratio for the first 6 months of life

This paper presents the development of reference standards for head circumference (HC), length and mid-arm circumference/head circumference (MAC/HC) ratio for the evaluation of exclusively breastfed infants. A total of 219 exclusively breastfed term appropriate-for-gestational age (AGA) infants were studied and analysed from 1 June 1995 to 31 May 1997 at the Neonatal Follow-up Clinic, University Teaching Hospital, Benin City, Nigeria. Head circumference and length measurements were recorded for the infants at each postnatal completed month. MAC/HC ratios were also computed for each infant at each completed postnatal month. There was a progressive increase in the mean measurements at the completed months with increasing postnatal age and the differences between the mean measurements of length and head circumference at the 4th and 6th completed months were significant (p < 0.001). The head circumference, length and MAC/HC ratio had significant correlations with postnatal age. The standards represent the regression lines of the anthropometric measurements and MAC/HC ratio on postnatal age with the corresponding 95 per cent confidence limits. The standards identified 95 per cent (for head circumference), 93 per cent (for length) and 94 per cent (for MAC/HC ratio) of exclusively breastfed healthy infants as having normal infant growth for age.