Maternal anaemia and risk of mortality: a call for action
Authors: Melissa F Young
Journal: The Lancet Global Health (2018)

Maternal anaemia is an important global health problem that affects about 500 million women of reproductive age.1Stevens GA Finucane MM De-Regil LM et al.Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995–2011: a systematic analysis of population-representative data.Lancet Glob Health. 2013; 1: e16-e25Summary Full Text Full Text PDF PubMed Scopus (1022) Google Scholar Much is known about the consequences of anaemia during pregnancy, including the increased risks of low birthweight, preterm birth, perinatal mortality, and neonatal mortality.2Rahman MM Abe SK Rahman MS et al.Maternal anemia and risk of adverse birth and health outcomes in low- and middle-income countries: systematic review and meta-analysis.Am J Clin Nutrit. 2016; 103: 495-504Crossref PubMed Scopus (277) Google Scholar Maternal anaemia also places the mother at increased risk of death during and after childbirth.3Black RE Victora CG Walker SP et al.Maternal and child undernutrition and overweight in low-income and middle-income countries.Lancet. 2013; 382: 427-451Summary Full Text Full Text PDF PubMed Scopus (4307) Google Scholar Severe anaemia can lead to circulatory decompensation, increased cardiac output, an increased risk of haemorrhage, and decreased ability to tolerate blood loss, leading to circulatory shock and death.4Kavle JA Stoltzfus RJ Witter F Tielsch JM Khalfan SS Caulfield LE Association between anaemia during pregnancy and blood loss at and after delivery among women with vaginal births in Pemba Island, Zanzibar, Tanzania.J Health Popul Nutr. 2008; 26: 232-240PubMed Google Scholar, 5Christian P Mullany LC Hurley KM Katz J Black RE Nutrition and maternal, neonatal, and child health.Semin Perinatol. 2015; 39: 361-372Crossref PubMed Scopus (122) Google Scholar A review3Black RE Victora CG Walker SP et al.Maternal and child undernutrition and overweight in low-income and middle-income countries.Lancet. 2013; 382: 427-451Summary Full Text Full Text PDF PubMed Scopus (4307) Google Scholar of observational studies showed a linear association between maternal anaemia and death, with each 10 g/L increase in maternal haemoglobin associated with a 29% reduction in maternal mortality (odds ratio [OR] 0·71 [95% CI 0·60–0·85]). In The Lancet Global Health, Jahnavi Daru and colleagues reaffirm the association of maternal anaemia with maternal mortality.6Daru J Zamora J Fernández-Félix BM et al.Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis.Lancet Glob Health. 2018; (published online March 20.)http://dx.doi.org/10.1016/S2214-109X(18)30078-0Summary Full Text Full Text PDF PubMed Scopus (150) Google Scholar Their study makes important contributions to the field and emphasises the need to reduce anaemia during pregnancy and post partum. A unique feature of this study is the use of data from WHO's Multicounty Survey, which is one of the largest studies of severe complications in pregnancy and includes diverse data from 29 countries. The authors concluded that severe anaemia (defined as haemoglobin concentrations of <70 g/L) during pregnancy or post partum doubled the risk of maternal death in this population.6Daru J Zamora J Fernández-Félix BM et al.Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis.Lancet Glob Health. 2018; (published online March 20.)http://dx.doi.org/10.1016/S2214-109X(18)30078-0Summary Full Text Full Text PDF PubMed Scopus (150) Google Scholar Although this estimate is alarming, it is probably an underestimation. The authors potentially over-controlled for factors in the causal pathway, and compared women with severe anaemia with all other women, including those with mild or moderate anaemia and high haemoglobin concentrations. Haemoglobin was assessed during pregnancy or the first week post partum, but information about timing was not recorded, which is problematic. Without these data it is hard to establish, for example, whether post-partum haemorrhage led to severe anaemia, or whether severe anaemia during pregnancy increased the risk of post-partum haemorrhage. In view of the absence of data for timing, the authors developed a conservative model in which they adjusted for potentially confounding variables (including post-partum haemorrhage, sepsis, transfusion, shock, and admission to intensive-care units, among other factors). However, the possibility that some of these factors are on the causal pathway, which would attenuate the relation between maternal anemia and mortality, cannot be ruled out. For instance, if severe anaemia leads to circulatory shock and results in death, then adjustment for shock would reduce the estimated effect of anaemia. The true estimate probably lies somewhere between the adjusted OR of 2·36 (95% CI 1·60–3·48) and the crude OR of 43·35 (35·03–53·65). The authors' analysis includes multiple models and sensitivity analyses. However, the cause of maternal mortality is complex and difficult to examine in cross-sectional surveys. Additionally, in the WHO Multicountry Survey, only severe anaemia is recorded. The inclusion in the control group of individuals at potentially heightened risk of mortality (ie, those with mild or moderate anaemia, or high haemoglobin concentrations) would also have attenuated the estimated effect of severe anaemia. In a Peruvian cohort,7Gonzales GF Tapia V Gasco M Carrillo CE Fort AL Association of hemoglobin values at booking with adverse maternal outcomes among Peruvian populations living at different altitudes.Int J Gynaecol Obstet. 2012; 117: 134-139Crossref PubMed Scopus (16) Google Scholar women with haemoglobin concentrations greater than 145 g/L (OR 2·01 [95% CI 1·12–3·61]), between 70 g/L and less than 90 g/L (6·06 [3·16–11·6]), or less than 70 g/L (8·54 [2·06–35·42]) had increased odds of maternal mortality compared with those with haemoglobin concentrations of 110–45 g/L. Questions remain about the optimal haemoglobin cutoffs to identify pregnant people at risk for poor birth outcomes and how these cutoffs are influenced by timing of measurement.8Dewey KG Oaks BM U-shaped curve for risk associated with maternal hemoglobin, iron status, or iron supplementation.Am J Clin Nutr. 2017; 106: 1694S-1702SCrossref PubMed Scopus (107) Google Scholar Further research, including longitudinal surveillance that records continuous haemoglobin measurements throughout pregnancy and follows up women for longer post partum, could help to improve understanding of the relation between maternal anaemia and mortality. The implication of Daru and colleagues' study is a call for action to address anaemia to reduce preventable maternal deaths. Even if this robust and conservative analysis underestimates the risk of death among women with severe anaemia, the risk remains unacceptability high.6Daru J Zamora J Fernández-Félix BM et al.Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis.Lancet Glob Health. 2018; (published online March 20.)http://dx.doi.org/10.1016/S2214-109X(18)30078-0Summary Full Text Full Text PDF PubMed Scopus (150) Google Scholar These results emphasise that addressing maternal anaemia should be part of an integrated maternal health strategy to reduce maternal mortality. The WHO global targets call for a 50% reduction in anaemia in women of reproductive age by 2025 relative to 2010 prevalence.9WHOGlobal nutrition targets 2025: anaemia policy brief (WHO/NMH/NHD/14.4). World Health Organization, Geneva2014Google Scholar Efficacious interventions, such as iron and folic acid supplementation,10WHOWHO recommendations on antenatal care for a positive pregnancy experience. World Health Organization, Geneva2016Google Scholar are available, but they do not seem to be working at scale as evidenced by insufficient progress in reducing maternal anaemia.1Stevens GA Finucane MM De-Regil LM et al.Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995–2011: a systematic analysis of population-representative data.Lancet Glob Health. 2013; 1: e16-e25Summary Full Text Full Text PDF PubMed Scopus (1022) Google Scholar The implementation of existing programmes needs to improve, and other approaches that reach women before conception and during pregnancy, such as mass fortification and home fortification, and that tackle non-nutritional causes of anaemia need to be developed. This study is a call to develop comprehensive strategies that address the diverse causes of anaemia across contexts to improve maternal and child health. I declare no competing interests. Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysisPrevention and treatment of anaemia during pregnancy and post partum should remain a global public health and research priority. Full-Text PDF Open Access