Randomised trial of early diet in preterm babies and later intelligence quotientBMJ 1998; 317 doi: https://doi.org/10.1136/bmj.317.7171.1481 (Published 28 November 1998) Cite this as: BMJ 1998;317:1481
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Editor - The publication in last week's journal of Lucas's paper1
sparked intense media interest. Once again the press reports that a
special infant formula makes a difference, this time to premature babies.
"Premature babies need enriched diets", said the BBC. They didn’t point
out any of the known advantages of breastmilk for premature babies, or
that the funding for the research on which they are reporting was
contributed to by a manufacturer of infant formula.
The paper compared babies who received only infant formula to babies
who received breastmilk and infant formula. In each case, babies
received either standard term formula (very rarely used now for premature
babies) or preterm formula. Looking at the main outcome, IQ at 7 - 8
years of age, the confidence intervals indicate no advantage for preterm
formula. The authors state that the advantage for babies receiving
breastmilk was previously reported. The Medline abstract referred to
quotes an 8.3 point advantage for babies receiving maternal milk
(p<_0.0001 with="with" a="a" dose-response="dose-response" effect="effect" observed="observed" and="and" the="the" advantage="advantage" associated="associated" breastmilk="breastmilk" itself="itself" rather="rather" than="than" process="process" of="of" breastfeeding="breastfeeding" milk="milk" was="was" tube="tube" fed.="fed." p="p"/> The authors next looked at IQ for those babies who received the
highest intakes of trial diet. Again the confidence intervals reported
show no significant advantage for preterm formula.
Next they divide the data into boys and girls. No details are given
about how successful the randomisation was in terms of sex of the baby.
Is it then valid to attempt to draw separate conclusions for boys and
girls? For example, if the group of boys were lighter, or sicker, this
must impact on the researchers’ ability to make inferences about the wider
population. Surely the most that can be concluded is that further
research in this area is warranted.
The authors stated conclusion is that "Preterm infants are vulnerable
to suboptimal early nutrition in terms of their cognitive performance at
7.5 - 8 years,…" and that "Cognitive function, notably in males, may be
permanently impaired by suboptimal neonatal nutrition." The stated key
messages are actually all about ‘potential’, ‘may’, ‘seems’. It would be
more accurate to conclude that "Breastmilk continues to be the feed of
choice for premature babies. The results did not show an advantage for
preterm formula in terms of cognitive performance at 7.5 - 8 years. The
data suggests that further work with a cohort randomised by sex would be
We were puzzled over the apparent delay in publishing this study.
The last data must have been collected in 1992 - and indeed the same data
was used in a paper published in that year. If it had contained anything
to change practice in the care of premature babies it should have been
published as soon as the results were known. Parents would be interested
in a wider picture than IQ measurements, and short and long term heath
outcomes would have been of relevance. It is unfortunate that it has
generated so much misleading publicity implying that "enriched" infant
formula gives an added benefit to babies, and this at a time when the
manufacturers of infant formula appear to be fighting for market share.
Witness the attempts to introduce LCPUFA enriched formula - which,
according to Table 1, was not included in this trial.
For infants breastfeeding is the physiological norm. It must be
assumed that any other method of feeding babies is risky, until proved
otherwise. The onus is on researchers to prove that any substitute is
both safe and beneficial. Indeed it is recommended that there should be a
breastfeeding reference group for all infant feeding research studies2.
Where research compares 2 breastmilk substitutes, it cannot be concluded
that either one is safer or better than breastmilk. When the sponsors of
research stand to gain from increased sales of infant formula, readers
must be aware of the conflict of interest.
Parents of babies in special care are particularly vulnerable, as are
their babies. For these babies, not only long term health gains are at
stake. Necrotising enterocolitis is a very real risk for premature
babies, and breastmilk plays a vital role in the truest sense of the word.
How tragic if a headline like "Premature babies need enriched diets" is
what tips the balance for a woman struggling to find the time and support
to express her milk for her baby, all the time doubting that she can
either produce the right quality or quantity for her vulnerable child. It
would confirm the work of health professionals and lay workers, and
support the parents who are working hard to provide breastmilk for sick or
premature babies, if press releases concerning infant feeding could
reiterate the simple message - ‘Breast is Best’.
Deborah Behrman, Mary Broadfoot, Phyll Buchanan, Carolanne Lamont, Magda
Sachs, Breastfeeding Supporters, the Breastfeeding Network PO Box 11126,
Paisley PA2 8YB
Competing interests: No competing interests