Abstract
SummaryBackgroundLow haemoglobin concentrations and anaemia are important risk factors for the health and development of women and children. We estimated trends in the distributions of haemoglobin concentration and in the prevalence of anaemia and severe anaemia in young children and pregnant and non-pregnant women between 1995 and 2011.MethodsWe obtained data about haemoglobin and anaemia for children aged 6–59 months and women of childbearing age (15–49 years) from 257 population-representative data sources from 107 countries worldwide. We used health, nutrition, and household surveys; summary statistics from WHO's Vitamin and Mineral Nutrition Information System; and summary statistics reported by other national and international agencies. We used a Bayesian hierarchical mixture model to estimate haemoglobin distributions and systematically addressed missing data, non-linear time trends, and representativeness of data sources. We quantified the uncertainty of our estimates.FindingsGlobal mean haemoglobin improved slightly between 1995 and 2011, from 125 g/L (95% credibility interval 123–126) to 126 g/L (124–128) in non-pregnant women, from 112 g/L (111–113) to 114 g/L (112–116) in pregnant women, and from 109 g/L (107–111) to 111 g/L (110–113) in children. Anaemia prevalence decreased from 33% (29–37) to 29% (24–35) in non-pregnant women, from 43% (39–47) to 38% (34–43) in pregnant women, and from 47% (43–51) to 43% (38–47) in children. These prevalences translated to 496 million (409–595 million) non-pregnant women, 32 million (28–36 million) pregnant women, and 273 million (242–304 million) children with anaemia in 2011. In 2011, concentrations of mean haemoglobin were lowest and anaemia prevalence was highest in south Asia and central and west Africa.InterpretationChildren's and women's haemoglobin statuses improved in some regions where concentrations had been low in the 1990s, leading to a modest global increase in mean haemoglobin and a reduction in anaemia prevalence. Further improvements are needed in some regions, particularly south Asia and central and west Africa, to improve the health of women and children and achieve global targets for reducing anaemia.FundingBill & Melinda Gates Foundation, Grand Challenges Canada, and the UK Medical Research Council.
Highlights
Low haemoglobin concentrations during pregnancy can be associated with an increased risk of maternal and perinatal mortality and low size or weight at birth.[2,4,5,6]
Some adverse effects are associated with high haemoglobin concentrations,[10] most take place along a continuum of low concentrations, with each decrement associated with worse outcomes
Other effects might be restricted to concentrations that correspond to moderate-to-severe anaemia.[2,4]
Summary
Low concentrations of haemoglobin, adversely affect cognitive and motor development and cause fatigue and low productivity.[1,2,3] Low haemoglobin concentrations during pregnancy can be associated with an increased risk of maternal and perinatal mortality and low size or weight at birth.[2,4,5,6] Maternal and neonatal deaths are a major cause of mortality in developing countries, and together cause between 2·5 million and 3·4 million deaths worldwide.[7,8,9] some adverse effects are associated with high haemoglobin concentrations,[10] most take place along a continuum of low concentrations, with each decrement associated with worse outcomes. In 2012, the 65th World Health Assembly approved an action plan and global targets for maternal, infant, and child nutrition, with a commitment to halve anaemia prevalence in women of reproductive age by 2025, from 2011 levels. Emphasis has been placed on the reduction of risk factors that adversely affect women and children, for example in the UN Secretary-General’s Every Woman Every Child initiative and the accompanying Global Strategy for Women’s and Children’s Health. To plan for these programmes and prioritise interventions, information is needed about haemoglobin and anaemia in women and Lancet Glob Health 2013; 1: e16–25
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