Climate change worsens global inequity in maternal nutrition
Authors: Mia M Blakstad, Emily R Smith
Journal: The Lancet Planetary Health (2020)

Despite progress to improve maternal, neonatal, and child health over three decades, 5 million children younger than 5 years die each year. The UN Sustainable Development Goals (SDGs) aim to reduce maternal mortality and end preventable deaths of neonates and children younger than 5 years, but these targets cannot be achieved without improving maternal nutrition. Climate change affects maternal, neonatal, and child health directly through maternal nutrition, environmental risks, and emerging infectious disease (appendix), but the effect will be worse in regions that are already battling malnutrition. Failing to address nutrition and climate change concurrently will slow down, or even reverse, progress if not urgently addressed. Climate change can exacerbate maternal malnutrition directly. Unpredictable rainfall and ambient temperatures adversely affect farmers' ability to reliably supply food to their families and to markets. Migration that is climate induced is accompanied by loss of livelihood and the ability to provide diets that are nutritionally adequate. Extreme weather events affect crop yields and the average supply of essential nutrients, such as calcium, folate, thiamine, and pyridoxine, which are crucial during pregnancy. For countries that are landlocked and deficit in food, a single extreme weather event can reduce the average annual nutrient supply by up to 7·6%.1Park CS Vogel E Larson LM Myers SS Daniel M Biggs B-A The global effect of extreme weather events on nutrient supply: a superposed epoch analysis.Lancet Planet Health. 2019; 3: e429-e438Summary Full Text Full Text PDF PubMed Scopus (5) Google Scholar Higher atmospheric carbon dioxide concentrations can also affect the nutritional composition of edible plants, upregulating production of carbon-dense micronutrients (eg, vitamin C) at the cost of essential nutrients such as protein, iron, and zinc.2Beach RH Sulser TB Crimmins A et al.Combining the effects of increased atmospheric carbon dioxide on protein, iron, and zinc availability and projected climate change on global diets: a modelling study.Lancet Planet Health. 2019; 3: e307-e317Summary Full Text Full Text PDF PubMed Scopus (28) Google Scholar Myers and colleagues estimate that by 2050, elevated carbon dioxide concentrations could push an additional 138 million people into zinc deficiency, with disproportionate burdens for children and pregnant or lactating women who have heightened nutritional requirements.3Myers SS Zanobetti A Kloog I et al.Increasing CO2 threatens human nutrition.Nature. 2014; 510: 139-142Crossref PubMed Scopus (578) Google Scholar Women and girls around the world often eat last and eat the least. When food insecurity gets worse, women and girls are affected the most. Infectious diseases have more serious consequences on maternal, fetal, neonatal, and child health, and this effect is exacerbated by maternal malnutrition. With deteriorating water quality, the incidence and severity of food-borne illness, diarrhoeal disease, and environmental enteric dysfunction, will rise. As temperatures and carbon dioxide concentrations increase, so do the density, geographical distribution, and rate of speciation of mosquitoes,4Tang C Davis KE Delmer C Yang D Wills MA Elevated atmospheric CO2 promoted speciation in mosquitoes (Diptera, Culicidae).Commun Biol. 2018; 1: 182Crossref Scopus (4) Google Scholar and therefore the burden of mosquito-borne diseases. Of particular concern is the broadening range of Zika virus vectors, suggesting that the global burden of pregnancy complications related to Zika virus infection could grow as temperatures rise.5Ryan SJ Carlson CJ Mordecai EA Johnson LR Global expansion and redistribution of Aedes-borne virus transmission risk with climate change.PLoS Negl Trop Dis. 2019; 13e0007213Crossref PubMed Scopus (144) Google Scholar Further, heat exposure could affect gut permeability through lower oxygen concentrations in the lumen, impairing the body's ability to absorb micronutrients that are already in low supply.6Lian P Braber S Garssen J et al.Beyond heat stress: intestinal integrity disruption and mechanism-based intervention strategies.Nutrients. 2020; 12: 734Crossref Scopus (15) Google Scholar The bidirectional relationship between malnutrition and infection is well established, and this relationship is especially important. Environmental health risks, such as air pollution and extreme heat events, are also linked to extra risk for pregnant women and their fetuses. A meta-analysis of 40 observational studies has linked exposure to PM2·5, PM10, nitrogen dioxide, carbon monoxide, sulphur dioxide, and ozone during pregnancy to low birthweight (<2500 g).7Li C Yang M Zhu Z et al.Maternal exposure to air pollution and the risk of low birth weight: a meta-analysis of cohort studies.Environ Res. 2020; 190109970Crossref Scopus (10) Google Scholar Similarly, meta-analyses suggest that high exposure to indoor air pollution from cooking stove fuel is linked to a 35% increased risk of low birthweight.8Amegah AK Quansah R Jaakkola JJK Household air pollution from solid fuel use and risk of adverse pregnancy outcomes: a systematic review and meta-analysis of the empirical evidence.PLoS One. 2014; 9e113920Crossref PubMed Scopus (114) Google Scholar Pregnant women are also susceptible to extreme heat events, although they are not often included as a population that are susceptible to heat.9Kuehn L McCormick S Heat exposure and maternal health in the face of climate change.Int J Environ Res Public Health. 2017; 14: 853Crossref Scopus (43) Google Scholar Extreme heat events when coupled with air pollution can interact to further exacerbate maternal and fetal stress in pregnancy, and excess heat exposure is also linked to preterm birth (<37 weeks' gestation).9Kuehn L McCormick S Heat exposure and maternal health in the face of climate change.Int J Environ Res Public Health. 2017; 14: 853Crossref Scopus (43) Google Scholar Adverse birth outcomes increase the risk of poor physical and cognitive development, and non-communicable disease in adulthood. The SDGs related to improving nutrition and mitigating the speed and consequences of climate change share common attributes. First, progress in both nutrition and climate change are key to achieving many of the other health-related goals, and we argue there is synergy between the nutrition and climate change agenda, which is particularly clear in the case of maternal nutrition. The problems are multisectoral; therefore, attention is needed from all sectors (eg, agriculture, energy, water and sanitation). Second, calls for climate action (eg, reducing consumption of animal source food10Willett W Rockström J Loken B et al.Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems.Lancet. 2019; 393: 447-492Summary Full Text Full Text PDF PubMed Scopus (1737) Google Scholar) should consider equity; pregnant and lactating women living in low-income countries already face the largest nutrient deficits. Finally, efforts to estimate the burden of climate change should consider the excess burden for women and children. Maternal, newborn, and child health targets must consider that current progress projections do not account for climate change. Better nutrition and resilience in the face of climate change is linked to each of the SDGs, but we must focus on equity in innovations to address the changing nutrient landscape and global food insecurity so that women and girls are not left behind. We declare no competing interests. Download .pdf (.16 MB) Help with pdf files Supplementary appendix