Higher bone mineral density at six years of age in very preterm-born infants fed human milk compared to formula feeding. A secondary analysis of an RCT.

Abstract

In very preterm-born infants, nutritional intake is important to reduce the risk of severe metabolic bone disease including the risk of a lower bone mineral density (BMD). The aim of this study was to evaluate bone mineral content (BMC) and BMD (measured as BMC per bone area (BA)) at six years of age in very preterm-born infants fed different diets post-discharge. Data on this topic so far is insufficient, and with this study we aim to supply more useful data. A prospective follow-up study of 281 children born very preterm (gestational age ≤ 32 + 0 weeks) and enrolled in a multicentre RCT on post-discharge nutrition. Infants fed human milk (HM) were randomised respectively to be fed unfortified HM (UHM) or fortified human milk (FHM) from hospital discharge to four months' corrected age. Those not fed HM received a preterm formula (PF). At six years of age, BMD and BMC in all the children were established by means of a dual-energy X-ray absorptiometry (DXA) scan (Lunar Prodigy) and adjusted for sex, age, and anthropometrics. A total of 192 very preterm-born children (59 fed UHM, 67 FHM and 66 PF) had a DXA scan performed at median 6 (5.8-8.3) years of age. No significant difference was found comparing UHM and FHM according to height, weight, BA, BMC, and BMD at six years of age. However, a multiple regression analysis showed significantly improved BMD in breastfed children compared to PF-fed children.

Conclusions: Fortified compared to non-fortified human milk post-discharge did not have an impact on BMD at 6 years of age in very preterm-born infants. Breastfed children demonstrated higher BMD than formula-fed children.

What is known: • Adequate nutritional intake is important to improve growth and to reduce the risk of severe bone disease in very preterm born infants. • Bone mineralization is attained later in preterm born infants compared to term born infants.

What is new: • Feeding human milk with fortification compared to non-fortified human milk did not improve bone mineral density in children born very preterm in this follow-up study at six years of age. • Feeding human milk compared to formula was associated with increased BMD at six years of age among very preterm born infants.