Exposure to extremes in weather during childhood and adulthood has increasingly well-known effects. Since those extremes are becoming more frequent, researchers and policymakers are working on ways to ameliorate their effects.
But what about the effects of weather extremes on human gestation and infancy? Although the womb provides a degree of protection from the outside world, major stresses on maternal health are likely to be reflected in newborn and infant health, and they must be taken into account as part of a larger response to climate change in IDB member countries as well as the rest of the world.
A step toward this assessment has been taken by Universidade de São Paulo economists Paula C. Pereda and Denisard Alves and Universidade Federal de Pernambuco economist Tatiane A. de Menezes as part of the Research Network project in “The Health Impacts of Climate Change in Latin America and the Caribbean.” The authors analyzed National Household Survey results, Primary Care System birthweight data and Brazilian Health Ministry infant mortality statistics from 2000 to 2011 in relation to weather data collected by Brazil’s National Meteorology Institute. Since Brazil is a vast and populous country with great variation in both climatic and socioeconomic conditions, findings there are likely to be applicable to countries both in the region and elsewhere, and to countries at different points on their development paths.
The analysis reached several notable conclusions. First, increased neonatal mortality—i.e., death within the first 27 days of birth—is associated with excessive rainfall across the country year-round, and in the largely impoverished Northeast during the summer. Neonatal mortality in the Northeast in the summer months also appears to be increased by above-average summer temperatures, while elevated summer temperatures raise autumn neonatal mortality in the Midwest region.
Weather appears to have a less definitive but nonetheless meaningful impact on low birth weight. Among rural households—which are more likely than others to be poor and suffer from inadequate housing—exposure to below-average temperatures during the third trimester of pregnancy leads to low birth weight, as does exposure to extremely high and low humidity. High temperatures during the second trimester of pregnancy are likewise associated with low birth weight among rural households.
Birth outcomes in Brazil are expected to be further affected by climate change in the decades ahead. The authors calculate potential impacts using scenarios of low, middle and high levels of human effects formulated by the United Kingdom’s Met Office-Hadley Centre, one of the world’s leading institutes in meteorology and climate science. In terms of infant mortality, the middle scenario predicts 305 deaths more than would otherwise occur nationwide each year from 2041 to 2070. This number may seem small, particularly in a country the size of Brazil, but two additional factors must be considered. First, the increase is concentrated in the already-disadvantaged Northeast and Southeast regions. Second, the trauma of losing a child can extend over the remainder of surviving parents’ and siblings’ lives, with serious consequences for emotional and physical well-being.
Low birth weight, which has been widely associated with diminished cognitive development and health over the course of a lifetime, is also expected to increase. The middle scenario foresees an additional 3,171 births under 2.5 kilograms annually from 2041 to 2070, broken down by month and compared with low scenarios in the figure below. This total is further divided into 1,922 urban cases of low birth weight and 1,249 rural cases, the latter disproportionately large in relation to the rural share of the population. Again, the poor and vulnerable suffer more.
Since no country can mitigate climate change alone, governments and citizens must find ways to adapt and increase their resilience to weather extremes. The relatively good news for Brazil is that, for birth outcomes, adaptation consists largely of increasing access to existing services and technologies. Increasing mothers’ educational level holds particular potential for reducing neonatal mortality, the highest rates of which occur among mothers who do not complete elementary school. Neonatal mortality can also be reduced by providing adequate sewage systems and by increasing the per capita number of nurses, who play a significant role in educating poor families on hygiene and primary care. The incidence of low birth weight can be reduced by a similar combination of measures. In rural areas adequate sewage systems are again important, and in both rural and urban areas the presence of a hospital in a household’s municipality makes mothers more likely to obtain the prenatal care that can prevent low birth weight and other problems.
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