Katrin Klebermass-Schrehof1, Thomas Waldhoer2, Lin Yang3,4. 1. Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics, Medical University of Vienna, Vienna, Austria. 2. Department of Epidemiology, Center for Public Health, Medical University of Vienna, Vienna, Austria. 3. Department of Cancer Epidemiology and Prevention Research, Alberta Health Services, Calgary, Canada. 4. Departments of Oncology and Community Health Sciences, University of Calgary, Calgary, Canada.
Abstract
Klebermass-Schrehof Katrin, Thomas Waldhoer, and Lin Yang. The effect of altitude on birthweight/length ratio: a population-based study over 36 years in an altitude range from sea level to 1,700 m. High Alt Med Biol. 23:90-95, 2022. Objective: The negative effect of altitude on fetal growth has been documented, but it is unknown whether this effect changes over time. We investigated the effect of altitude on infant birthweight/length ratio as well as its potential dependence on gestational age and year of birth in the range from sea level up to 1,700 m (Austria). Materials and Methods: Data on maternal characteristics, infant birthweights, and infant lengths were extracted from all Austrian birth certificates between 1984 and 2019. Results: A total of 2,240,439 birth certificates were identified and analyzed. The effect of altitude on birthweight/length ratio was -2.66 g/cm (95% confidence interval [CI]: -2.77 to -2. 54) per 1,000 m increased altitude in 1984-1986, which decreased to -1.96 g/cm (95% CI: -2.09 to -1.82) in 2017-2019. The effect of altitude on birthweight/length ratio remained constant for preterm infants, which fluctuated around -1.5 g/cm. For term infants, the negative effect of altitude on birthweight/length ratio attenuated from -3 to -1.9 g/cm over time with a stronger decrease for infants born between 41 and 42 compared with those between 37 and 40 weeks of gestation. Conclusion: In summary, our data demonstrate a strong effect of altitude on birthweight/length ratio over 36 years with a smaller effect in recent years and a stronger effect in infants born around term age compared with preterm infants.
Klebermass-Schrehof Katrin, Thomas Waldhoer, and Lin Yang. The effect of altitude on birthweight/length ratio: a population-based study over 36 years in an altitude range from sea level to 1,700 m. High Alt Med Biol. 23:90-95, 2022. Objective: The negative effect of altitude on fetal growth has been documented, but it is unknown whether this effect changes over time. We investigated the effect of altitude on infant birthweight/length ratio as well as its potential dependence on gestational age and year of birth in the range from sea level up to 1,700 m (Austria). Materials and Methods: Data on maternal characteristics, infant birthweights, and infant lengths were extracted from all Austrian birth certificates between 1984 and 2019. Results: A total of 2,240,439 birth certificates were identified and analyzed. The effect of altitude on birthweight/length ratio was -2.66 g/cm (95% confidence interval [CI]: -2.77 to -2. 54) per 1,000 m increased altitude in 1984-1986, which decreased to -1.96 g/cm (95% CI: -2.09 to -1.82) in 2017-2019. The effect of altitude on birthweight/length ratio remained constant for preterm infants, which fluctuated around -1.5 g/cm. For term infants, the negative effect of altitude on birthweight/length ratio attenuated from -3 to -1.9 g/cm over time with a stronger decrease for infants born between 41 and 42 compared with those between 37 and 40 weeks of gestation. Conclusion: In summary, our data demonstrate a strong effect of altitude on birthweight/length ratio over 36 years with a smaller effect in recent years and a stronger effect in infants born around term age compared with preterm infants.
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Keywords:
altitude; birthweight; birthweight/length ratio; length; population-based study