Introduction
- Preterm birth relates to long-term alteration in cardiac
morphology and function
- We hypothesized that fed human breast milk during early postnatal
life is beneficial to long-term cardiac structure and function in preterm-born individuals
compared with infant formulas.
Methods
-926 preterm-born infants originally took part in RCT of
postnatal milk-feeding regimes between 1982
and 1985 across 5 different UK centres.
- These individuals had birth
weight of <1850g and had no major
congenital anomalies
- They were randomly
assigned to either breast milk
donated by unrelated lactating women or
nutrient-enriched formulas.
- 102 individuals from this cohort were followed: 30 were fed exclusively human milk (EHM)
and 16 were fed exclusively formula (EFF)
- Comparison group: 102 individual born term to
uncomplicated pregnancies with age and sex distribution similar to those of the
preterm-born young adults
- Cardiac morphology and function were assessed by MRI (1.5-T
Siemens Sonata scanner)
- All data were coded with subject- and study-specific IDs to
ensure anonymity and blinded analysis
Results
- No significant differences in both groups in perinatal
characteristics or anthropometrics, demographics, blood biochemistry, or blood pressure
in young adulthood (Table 1)
- However, both groups had altered blood biochemistry
profiles and increased blood pressures compared with young adults born term
- There were no significant differences in number of
smokers, personal and family medical history, or lifestyle factors, such as
socioeconomic status, physical activity, or diet (P > .05) between the 2 milk-feeding preterm
groups, nor with control group.
Left and Right Ventricular Size and Function
Compared with preterm-born individuals who were exclusively
formula fed as infants, preterm-born individuals fed exclusively human milk as infants had:
- Increased left and right ventricular end-diastolic volume
index (+9.73%, P = .04 and +18.2%, P < .001) and
- Increased left and right stroke volume index (+9.79%, P
= .05 and +22.1%, P = .01)
- Although both feeding groups still had significantly
smaller left ventricular end-diastolic volume index and stroke volume index
than adults born term, the reduction in the group fed EHM was only ∼9%
compared with 18% in the group fed EFF for both left ventricular end diastolic volume
index and stroke volume index.
- Both preterm-born groups had similar left ventricular mass
index and ejection fraction, although the preterm group fed EFF had
significantly shorter left ventricles with reduced left ventricular luminal
diameters.
- Right ventricular mass index and length were similar
between preterm groups (Table 2). However, preterm-born young adults fed EHM
had similar right ventricular ejection fractions as term-born young adults,
whereas preterm-born young adults fed EFF showed reduced right ventricular ejection
fractions compared with term-born controls.
Left Ventricular Shape and Native T1 Imaging
- Shape analysis confirmed the differences in size observed
by using standard metrics (Fig 3), which particularly highlighted the
significant increase in left ventricular length (P < .001) in the EHM
group compared with the preterm individuals fed EFF
- Importantly, there were no other major geometric
variations identified between preterm-born individuals fed EHM and those fed
EFF (Fig 3) or term-born adults.
- We did not observe significant differences in myocardial
tissue characterization by T1 mapping
Predictors of Cardiac Changes
- In multivariable models including gestational age, sex,
postnatal milkfeeding group, and postnatal weight gain, gestational age
remained an independent predictor for all 4 cardiac measures (P <
.001); however, being fed EHM was also an
independent predictor of left ventricular end-diastolic volume index (P =
.007), left ventricular stroke volume
index (P = .03), right
ventricular end-diastolic volume index (P = .002), and right ventricular stroke volume index (P
= .004).
- In line with the changes between preterm feeding groups being
greater for the right ventricle, in a multivariable regression model across the
entire preterm group (n = 102) with gestational age, sex, percentage of
human milk in the diet, and postnatal weight gain as the predictors, the percentage of human milk was positively
related to both right ventricular end-diastolic volume index (P =
.009) and stroke volume index (P =
.04), but not left ventricular
parameters.
- There were no correlations between percentage of expressed
milk and cardiac measures within the group fed EHM.
Thoracic Cavity Size and Pulmonary Artery Diameters
- Preterm-born young adults fed EFF had reduced thoracic
cavity dimensions compared with those fed EHM
- No difference in aortic diameters
- EFF groups had increased main pulmonary artery diameters and
pulmonary artery to aortic diameter ratios. Pulmonary artery to aortic diameter
ratios were inversely related to right ventricular end-diastolic volume index
and stroke volume index but not left ventricular parameters.
Discussion
- Breast milk
contains a greater bioactivity and bioavailability of a number of growth
factors, enzymes, and antibodies compared with even the best infant formulas.
These factors are relevant to normal growth and development, as well as
improving preterm infant health
- The data suggest that breast
milk may reduce the risk of pulmonary arterial hypertension and future cardiopulmonary disease in preterm-born
individuals
- These findings suggest the changes in cardiac morphology observed
in preterm-born individuals relate primarily to size rather than geometric alterations,
and that breast milk leads to
proportional normalization of size.
- support the necessity
of breast milk as part of early nutrition for individuals born to pregnancy
complications as a protective mechanism
to cardiovascular development
- Although our data suggest that it is not possible to
reverse all cardiac changes related to the degree of prematurity through breast
milk feeding, the magnitude of the differences
between preterm-born adults fed EHM and those fed EFF is substantial and occurs
independent of gestational age.
- Our finding that percentage of human milk consumed was
positively associated with right ventricular morphology and function suggests
that even small amounts of human milk in
the preterm postnatal diet may be beneficial
Limitation
- This study does not prove causality
- Number of participants were relatively small compared with
the size of the original cohort
- This study was not fully randomized, and as such, there is
risk of ascertainment bias.
Strength
- Our preterm groups were similar in baseline demographics and
demographic characteristics in young adulthood
- Unlike other studies that often rely on questionnaires and
recall, we can be certain of the exact dietary intake of our preterm-born
individuals during early postnatal life
Conclusion
- This is the first evidence of a beneficial association between
breast milk and cardiac morphology and function in adult life for those born
preterm
- Support promotion of human milk for the care of preterm
infants to reduce long-term cardiovascular risk
No comments:
Post a Comment