Nutritional interventions to prevent stunting of infants and young children are most
often applied in rural areas in low‐ and middle‐income countries (LMIC). Few interventions
are focused on urban slums. The literature needs a systematic assessment, as infants
and children living in slums are at high risk of stunting. Urban slums are complex
environments in terms of biological, social, and political variables and the outcomes
of nutritional interventions need to be assessed in relation to these variables. For
the purposes of this review, we followed the UN‐Habitat 2004 definitions for low‐income
informal settlements or slums as lacking one or more indicators of basic services
or infrastructure. To assess the impact of nutritional interventions to reduce stunting
in infants and children under five years old in urban slums from LMIC and the effect
of nutritional interventions on other nutritional (wasting and underweight) and non‐nutritional
outcomes (socioeconomic, health and developmental) in addition to stunting. The review
used a sensitive search strategy of electronic databases, bibliographies of articles,
conference proceedings, websites, grey literature, and contact with experts and authors
published from 1990. We searched 32 databases, in English and non‐English languages
(MEDLINE, CENTRAL, Web of Science, Ovid MEDLINE, etc). We performed the initial literature
search from November 2015 to January 2016, and conducted top up searches in March
2017 and in August 2018. Research designs included randomised (including cluster‐randomised)
trials, quasi‐randomised trials, non‐randomised controlled trials, controlled before‐and‐after
studies, pre‐ and postintervention, interrupted time series (ITS), and historically
controlled studies among infants and children from LMIC, from birth to 59 months,
living in urban slums. The interventions included were nutrition‐specific or maternal
education. The primary outcomes were length or height expressed in cm or length‐for‐age
(LFA)/height‐for‐age (HFA) z‐scores, and birth weight in grams or presence/absence
of low birth weight (LBW). We screened and then retrieved titles and abstracts as
full text if potentially eligible for inclusion. Working independently, one review
author screened all titles and abstracts and extracted data on the selected population,
intervention, comparison, and outcome parameters and two other authors assessed half
each. We calculated mean selection difference (MD) and 95% confidence intervals (CI).
We performed intervention‐level meta‐analyses to estimate pooled measures of effect,
or narrative synthesis when meta‐analyses were not possible. We used P less than 0.05
to assess statistical significance and intervention outcomes were also considered
for their biological/health importance. Where effect sizes were small and statistically
insignificant, we concluded there was 'unclear effect'. The systematic review included
15 studies, of which 14 were randomised controlled trials (RCTs). The interventions
took place in recognised slums or poor urban or periurban areas. The study locations
were mainly Bangladesh, India, and Peru. The participants included 9261 infants and
children and 3664 pregnant women. There were no dietary intervention studies. All
the studies identified were nutrient supplementation and educational interventions.
The interventions included zinc supplementation in pregnant women (three studies),
micronutrient or macronutrient supplementation in children (eight studies), nutrition
education for pregnant women (two studies), and nutrition systems strengthening targeting
children (two studies) intervention. Six interventions were adapted to the urban context
and seven targeted household, community, or 'service delivery' via systems strengthening.
The primary review outcomes were available from seven studies for LFA/HFA, four for
LBW, and nine for length. The studies had overall high risk of bias for 11 studies
and only four RCTs had moderate risk of bias. Overall, the evidence was complex to
report, with a wide range of outcome measures reported. Consequently, only eight study
findings were reported in meta‐analyses and seven in a narrative form. The certainty
of evidence was very low to moderate overall. None of the studies reported differential
impacts of interventions relevant to equity issues. Zinc supplementation of pregnant
women on LBW or length (versus supplementation without zinc or placebo) (three RCTs)
There was no evidence of an effect on LBW (MD –36.13 g, 95% CI –83.61 to 11.35), with
moderate‐certainty evidence, or no evidence of an effect or unclear effect on length
with low‐ to moderate‐certainty evidence. Micronutrient or macronutrient supplementation
in children (versus no intervention or placebo) (eight RCTs) There was no evidence
of an effect or unclear effect of nutrient supplementation of children on HFA for
studies in the meta‐analysis with low‐certainty evidence (MD –0.02, 95% CI –0.06 to
0.02), and inconclusive effect on length for studies reported in a narrative form
with very low‐ to moderate‐certainty evidence. Nutrition education for pregnant women
(versus standard care or no intervention) (two RCTs) There was a positive impact on
LBW of education interventions in pregnant women, with low‐certainty evidence (MD
478.44g, 95% CI 423.55 to 533.32). Nutrition systems strengthening interventions targeting
children (compared with no intervention, standard care) (one RCT and one controlled
before‐and‐after study) There were inconclusive results on HFA, with very low‐ to
low‐certainty evidence, and a positive influence on length at 18 months, with low‐certainty
evidence. All the nutritional interventions reviewed had the potential to decrease
stunting, based on evidence from outside of slum contexts; however, there was no evidence
of an effect of the interventions included in this review (very low‐ to moderate‐certainty
evidence). Challenges linked to urban slum programming (high mobility, lack of social
services, and high loss of follow‐up) should be taken into account when nutrition‐specific
interventions are proposed to address LBW and stunting in such environments. More
evidence is needed of the effects of multi‐sectorial interventions, combining nutrition‐specific
and sensitive methods and programmes, as well as the effects of 'up‐stream' practices
and policies of governmental, non‐governmental organisations, and the business sector
on nutrition‐related outcomes such as stunting. Effects of nutritional interventions
to increase nutritional status in children living in urban slums in low‐ and middle‐income
countries UN‐Habitat estimates that there are at least one billion people living in
urban slums, that is, places in cities without adequate access to health care, clean
water, and sanitation. For this review, we defined low‐income informal settlements
or slums as lacking one or more indicators of basic services or infrastructure. More
than 90% of these slums are in low‐ and middle‐income nations and the residents are
usually living in poverty, with little food security. One consequence of an inadequate
diet is growth stunting, that is, very short stature for age. Stunting is associated
with greater susceptibility to infection, cognitive (memory and thinking skills) and
behavioural problems, and lower adult work performance and earnings. About 25% of
children living in urban settings in low‐ and middle‐income countries are stunted.
In slum areas, this figure is higher. For example, in Dhaka, Bangladesh it is 48%,
and in Pune, India it is 59% of children under five years old. Nutritional methods
(interventions) to improve infant and young children's growth have not been comprehensively
or systematically assessed for urban slums. We included 15 studies in the review,
involving 9261 children less than five years old and 3664 pregnant women. About 73%
of children were less than one year old. The interventions provided maternal education;
nutrient supplementation of mothers, infants, and children; improving nutrition systems;
or a combination of these but not dietary modification. The reliability of the studies
was very low to moderate overall because studies were not designed to cope with research
problems linked to urban slum communities, such as high mobility and high loss of
participants to follow‐up. This meant that the effectiveness of the intervention could
not be properly assessed at later dates. We assessed the effect of interventions taking
both statistical and clinical significance into account. Where intervention outcomes
were statistically insignificant, we conclude there was 'unclear effect'. There was
no effect of giving mothers nutrient supplementation on birth weight and length, there
were inconclusive results for nutrient supplementation in infants and children on
improving children's height or stunting status, there was a positive impact on birth
weight of maternal education interventions where there was a positive difference in
birth weight of 478 g in infants exposed to the intervention, and inconclusive results
of improving health systems that support nutrition on children's stunting status and
a positive effect on height. There were no reported side effects from these interventions.
The review showed the need to better understand urban slum environments and their
people as evidence showed that interventions included in this review were successful
in other locations outside of urban poor areas. More evidence is needed of the effects
of multi‐sectorial interventions, combining nutrition‐specific and sensitive methods
and programmes, as well as the effects of 'up‐stream' practices and policies of governmental,
non‐governmental organisations (NGOs), and the business sector to improve low birth
weight and stunting in poor urban environments.