|Breast Milk Associated With Greater Mental Development
in Preterm Infants, Fewer Re-hospitalizations
Extremely low birth weight premature infants who received breast
milk shortly after birth, while still in intensive care units,
had greater mental development scores at 30 months than did infants
who were not fed breast milk, reported researchers in an NIH network.
Moreover, infants fed breast milk were less likely to have been
re-hospitalized after their initial discharge than were the infants
not fed breast milk.
The study is a follow up to a previous study in which the same
infants were tested at 18 months, showing that the breast-fed infants
held the developmental gains seen in the earlier study.
"These findings strongly suggest that, whenever possible, preterm
infants should routinely be given breast milk during their stay
in the intensive care unit," said Duane Alexander, M.D., Director
of the NICHD, the NIH institute that conducted the study.
The study appears in the October 1 issue of Pediatrics.
Betty R. Vohr, M.D., of the Department of Pediatrics at Brown Medical
School, led a team of researchers in the NICHD Neonatal Research
Network, at her own and other institutions, to conduct the study.
Extremely low birth weight infants are the tiniest and most fragile
of premature infants, weighing less than 1,000 grams, or 2.2 pounds,
at birth, explained Rose Higgins, M.D., the NICHD author of the
current study and the program officer for the NICHD Neonatal Research
Network. This category of infants makes up about 1 percent of all
U.S. births, or roughly 40,000 each year.
Researchers have long known the benefits of breast milk for full
term infants, but its potential effects in preterm infants had
not been well studied, Dr. Higgins added. Full term infants given
breast milk are less likely to develop diarrheal diseases, skin
allergies, ear infections, or upper respiratory infections. Some
studies indicate that they are less likely to be overweight or
obese as adults. To conduct the study, the researchers tracked
the breast milk intake of 773 extremely low birth weight infants
in the neonatal intensive care units at 12 sites in the NICHD Neonatal
Research Network, between 1999 and 2001.
The children in the current study were divided into five groups
by the quantity of breast milk they had ingested while in the NICU.
The majority of the infants had been given at least some breast
milk while in the NICU. Only about one-fifth of the children in
the study had not been fed any breast milk.
The researchers found that the benefits of breast milk first seen
at 18 months were still present at 30 months. Children who had
been given breast milk received higher scores on the Mental Developmental
Index (MDI), a test measuring the children's overall intelligence.
The average MDI score was 76.5 for children who had not received
any milk in the NICU, compared to a score of 89.7 for children
who had received the greatest amount of breast milk. Children who
had been given breast milk also showed greater ability to control
and appropriately respond to emotions and were also less likely
to have been readmitted to the hospital after their discharge and
before 30 months.
There was no difference in the amount of growth or the rate of
cerebral palsy in children who had received breast milk in the
NICU compared with those who had not.
The researchers hypothesized that breast milk may boost the children's
immunity against respiratory infections, the principal reason children
who had not received breast milk were hospitalized.
"Breast milk offers immune advantages for the infant. It has natural
substances that protect against infection," said Dr. Higgins.
Because they are unable to feed themselves, premature infants
receive fluids and nutrients intravenously. Gradually, breast milk
is dripped into their stomachs through a feeding tube. When the
infants are healthy enough, the intravenous tube can be removed
and the baby can receive all its nutrition from the feeding tube.
In the previous study, the researchers found that infants who had
ingested breast milk were able to leave the neonatal intensive
care unit sooner and were able to make the transition faster from
intravenous feeding to receiving all their nutrition through a
feeding tube than were infants receiving formula.
Dr. Higgins explained that earlier studies of term infants had
found that infants who were breastfed tended to score higher on
tests of mental development than did those who were not. She noted
that mothers who breast feed their infants tend to have more education
than those who do not breast feed. For this reason, the researchers
were unsure whether the breast fed infants' higher test scores
resulted from their consumption of breast milk or from the fact
that their more educated mothers were able to provide them with
greater intellectual stimulation.
In the current study, mothers who provided breast milk for their
infants also tended to have more education than those who did not.
However, in their analysis of the data, the researchers mathematically
compensated for the mothers' educational levels. With this adjustment,
the researchers concluded that consumption of breast milk had a
positive effect on infants' mental development scales, independent
of mothers' educational levels.
The researchers concluded that all health care professionals — obstetricians,
neonatologists, lactation consultants and primary care providers — who
come in contact with pregnant women and with new mothers should
explain to them the benefits of breast feeding.
The NICHD sponsors research on development, before and after birth;
maternal, child, and family health; reproductive biology and population
issues; and medical rehabilitation. For more information, visit
the Institute's Web site at http://www.nichd.nih.gov/.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.