Recent research that analysed repeated blood pressure measurements in more than 7 000 participants has suggested that outdoor humidity and temperature levels during pregnancy could affect the future BP of the unborn child, said the scientists.
The study, part of the LongITools project by the University of Bristol, showed that exposure to relative humidity and temperature levels during pregnancy was linked to BP changes in the children, that higher relative humidity in pregnancy was associated with a steeper increase in blood pressure, and that prenatal exposure to higher temperature with a slower increase in blood pressure, especially in childhood from three to 10-years-old.
Although an increase in blood pressure is normal during this age range, these weather-related factors were associated with a different rate of increase, especially in childhood, said the authors in JACC: Advances.
Previous studies have mostly measured BP at a single time point, predominantly focusing on single exposures, particularly air pollution.
In this study, using repeated measures of blood pressure, researchers aimed to assess the association of a range of prenatal urban environmental exposures with changes in systolic and diastolic blood pressure from childhood to early adulthood.
The study analysed repeated blood pressure measurements in more than 7 000 participants aged between three and 24 from Bristol’s Children of the 90s study, a world-leading longitudinal study, to assess the relationship of various characteristics of the urban environment in pregnancy with blood pressure from childhood to early adulthood.
Analyses were repeated in four independent European cohorts in more than 9 000 individuals in Finland, France and the Netherlands.
The research team explored 43 different measures of noise, air pollution, built environment, natural spaces, traffic, meteorology and unhealthy food environment, and found that prenatal outdoor temperature and humidity could influence changes in blood pressure, especially in childhood.
Overall, the study showed:
• Higher humidity was associated with a faster increase and higher temperature with a slower increase in systolic blood pressure in childhood.
• Higher humidity was associated with a faster increase in diastolic blood pressure in childhood.
In the UK cohort, higher levels of air pollution were associated with a faster increase in diastolic blood pressure in childhood and a slower increase in adolescence, but this association was not replicated in other cohorts.
There was little evidence of an association of other urban environmental exposures with changes in systolic or diastolic blood pressure.
Dr Ana Gonçalves Soares, Research Fellow in Epidemiology in the Bristol Medical School: Population Health Studies and lead researcher, said: “Children with higher blood pressure are more likely to have higher BP as adults, which can increase the risk of heart disease and stroke as well as kidney disease and vascular dementia.
“Previous studies have already shown that some urban environmental exposures during pregnancy are associated with blood pressure in childhood. We were able to expand that further and explore whether these environmental exposures are also associated with trajectories (changes) of blood pressure from childhood to early adulthood.
“The findings suggest that humidity and temperature during pregnancy could change the child’s blood pressure. Further work is needed to be carried out to understand how weather-related conditions during pregnancy can affect this, to inform strategies to prevent cardiovascular disease in later adulthood related to prenatal environmental exposures.”
Study details
Prenatal urban environment and blood pressure trajectories from childhood to early adulthood Prenatal Urban Environment and Blood Pressure Trajectories From Childhood to Early Adulthood
Ana Gonçalves Soares, Susana Santos, Nicholas Timpson, et al.
Published in JACC: Advances in February 2024
Abstract
Background
Prenatal urban environmental exposures have been associated with blood pressure in children. The dynamic of these associations across childhood and later ages is unknown.
Objectives
The purpose of this study was to assess associations of prenatal urban environmental exposures with blood pressure trajectories from childhood to early adulthood.
Methods
Repeated measures of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were collected in up to 7,454 participants from a UK birth cohort. Prenatal urban exposures (n = 43) covered measures of noise, air pollution, built environment, natural spaces, traffic, meteorology, and food environment. An exposome-wide association study approach was used. Linear spline mixed-effects models were used to model associations of each exposure with trajectories of blood pressure. Replication was sought in 4 independent European cohorts (up to 9,261).
Results
In discovery analyses, higher humidity was associated with a faster increase (mean yearly change in SBP for an interquartile range increase in humidity: 0.29 mm Hg/y, 95% CI: 0.20-0.39) and higher temperature with a slower increase (mean yearly change in SBP per interquartile range increase in temperature: −0.17 mm Hg/y, 95% CI: −0.28 to −0.07) in SBP in childhood. Higher levels of humidity and air pollution were associated with faster increase in DBP in childhood and slower increase in adolescence. There was little evidence of an association of other exposures with change in SBP or DBP. Results for humidity and temperature, but not for air pollution, were replicated in other cohorts.
Conclusions
Replicated findings suggest that higher prenatal humidity and temperature could modulate blood pressure changes across childhood.
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