The first 1,000 days represents the development of a child
from conception through to 2 years of age. Maternal and infant nutrition during
this period has become the corner stone of many international programmes to
combat malnutrition. The message relayed within this area is simple: Optimal
height for age and optimal cognitive function are largely determined during the
first 1,000 days. If a child suffers poor nutrition during this period, then
there is permanent reduction in stature and a permanent loss of cognitive
function. The UN initiative “Scaling Up Nutrition” (SUN) which has now been
adopted by 45 countries has the first 1,000 days and maternal-infant nutrition
as its core. However, a recent review and analysis published in the American
Journal of Clinical Nutrition and led by Andrew Prentice of the London School
of Hygiene and Tropical Medicine[1],
would certainly demand a more rigorous review of a policy which effectively
espouses the view that the first 1,000 days is the make-or-break period for
physical development.
The paper begins by describing the data upon which the first
1,000 days theory is based. These data show that in 54 countries with low
incomes, children are born with heights below the WHO growth standards and that
this height deficit deteriorates over the first 2 years of life and then
remains stable for the remainder of the study, which lasted 5 years. The
authors point out that these data come from an “amalgamation of large-scale nationally representative data sets that
were not collected for research purposes”.
They also point out that the original data from Africa does show some,
albeit modest recovery in height between 24 and 48 months.
The second point made by the authors is that whereas most
brain and neuronal development takes place in the first 1,000 days, most other
tissues show significant growth after this period, all of which are driven by
hormonal development, differing for males and females. The peak growth of
lymphoid tissue occurs between 5 and 10 years of age while muscles, bones and
reproductive organs show a surge in growth in the early to mid teens. If
different organs grow at different rates at different ages, then it is logical
to assume that sub-optimal nutrition can modify this growth well outside the
first 1,000 days. The authors present data from Brazil, Guatemala, The
Philippines and South Africa, which clearly shows recovery in height after the
first 1,000 days and that this recovery is not
based on any special nutrition intervention. India is exceptional in not
showing any post 2-year height recovery. The research base of Andrew Prentice
is in rural Gambia and over 6 decades, the growth of children from local subsistence
farming villages has been recorded. The data show the expected fall in height
in the first 1,000 days of these poor children. However, it shows very good
recovery thereafter. Then as growth demands are increased in puberty, there is
a temporary fall in height for age, which again shows recovery and plateaus in
the second decade of life. All of these
data challenge the concept that the first 1,000 days is the only critical
period of growth and that interventions outside that period are unlikely to
have any effect.
The authors now move on to look at the actual evidence of the
effects of nutritional intervention during pregnancy and early childhood. As
regards pregnancy, the authors cite the Cochrane Review of 23 protein-energy
supplement trials reached the following conclusion[2]:
“Dietary advice appears effective in
increasing pregnant women's energy and protein intakes but is unlikely to
confer major benefits on infant or maternal health. Balanced energy/protein
supplementation improves fetal growth and may reduce the risk of fetal and
neonatal death. High-protein or balanced protein supplementation alone is not
beneficial and may be harmful to the infant. Protein/energy restriction of
pregnant women who are overweight or exhibit high weight gain is unlikely to be
beneficial and may be harmful to the infant.” The authors also cite
meta-analyses of pre-natal trials involving 17 with zinc supplementation and 49
with iron and folic acid supplementation. The outcome of the meta-analyses was
that these nutritional supplements produced non-significant effects on birth
outcome. As the authors point out, these trials cannot be dismissed and furthermore
cannot be considered to be flawed by design. They then cite a meta-analysis of
42 trials, which involved nutritional intervention in childhood involving
complimentary feeding. Whereas some benefits were seen such as reduced rates of
anaemia and improved micronutrient status, the authors argue “ in the context
of the current discussion their analysis underscores the fact that the range of
interventions before 24 months reported to date could only make a limited
contribution to reducing stunting in poor populations”. Disappointing as they
may be, again these studies cannot be dismissed. It may well be, as the authors
argue, that a combination of poor hygiene, infection and infestation may negate
any nutritional impact and they point out that trials combining both dietary
and hygiene interventions are underway.
This is a very important paper and one that will trouble the
first 1000-day proponents. It is also a very thoughtful paper because it
emphasizes that that the first 1,000 days remains a very important period for
potential life long impacts on growth. However, it is a paper that challenges
both the strength of evidence of the first 1000 days and the concept that other
critical periods of growth are of lesser importance. The authors did not
consider cognition as an outcome of the first 1,000-day nutritional
intervention. However, they do cite 2 papers, which challenge the view that
cognitive development is again, confined to the first 1,000 days.
