Fortification of breast milk in VLBW infants: metabolic acidosis is linked to the composition of fortifiers and alters weight gain and bone mineralization.
OBJECTIVE
Study objectives were to test (a) whether increased incidence of metabolic acidosis (MA) was caused by introduction of a new commercially available fortifier for breast milk, (b) if so, whether its modification would decrease the incidence of MA and (c) to analyze the impact of MA on growth.


METHODS
Double-blind randomized design. Healthy breast-fed infants (≤34 gestational weeks). Primary outcome measure was incidence of MA (BE < -6.0 mmol/L). Secondary outcome measures were growth, bone mineral content (BMC), vital signs, treatment with sodium hydrogen carbonate and Ca and laboratory parameters (pH, pCO₂, HCO₃⁻, electrolytes).


RESULTS
Part 1 (comparison of standard (SF) and new fortifier (NF)): Interim analysis showed MA in 1 out of 7 (SF) and 7 out of 8 (NF) infants, p = 0.01; therefore the study was interrupted; subsequently the fortifier was adapted by modifying mineral components. Part 2 (comparison of SF and reformulated fortifier (RF)): MA occurred in 3 out of 15 (SF) and 6 out of 19 (RF), p = 0.7. When data of all infants studied, those with MA had lower mean weight gain (median: 9 vs. 21 g/kg/d, p < 0.01) and lower BMC (1.6% vs. 1.9% BMC/lean, p = 0.04) at discharge.


CONCLUSIONS
When fed fortified breast milk, mild MA spontaneously may develop in 20-30% of VLBW infants. A fortifier with an inappropriate composition may increase the severity and frequency of MA. Our data show that weight gain and BMC seem to be related to acid-base homeostasis. It may be speculated that inadequate growth of fully fed preterm infants is triggered more often by imbalances of acid-base status than previously expected.
Rochow
Niels
N
Division of Neonatology, University Children's Hospital, Ernst-Moritz-Arndt University, 17475 Greifswald, Germany.
Jochum
Frank
F
Redlich
Anke
A
Korinekova
Zuzana
Z
Linnemann
Kristina
K
Weitmann
Kerstin
K
Boehm
Günther
G
Müller
Heike
H
Kalhoff
Hermann
H
Topp
Heinrich
H
Hoffmann
Wolfgang
W
Fusch
Christoph
C
D000138:Acidosis / Q000378:metabolism*; D001942:Breast Feeding; D002113:Calcification, Physiologic; D004311:Double-Blind Method; D005527:Food, Fortified; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight / Q000254:growth & development*; D016014:Linear Models; D016015:Logistic Models; D008895:Milk, Human; D015999:Multivariate Analysis; D015430:Weight Gain