The impact of altitude on birth weight depends on further mother- and infant-related factors: a population-based study in an altitude range up to 1600 m in Austria between 1984 and 2013

• Published in: Journal of perinatology Vol. 35; no. 9; pp. 689 - 694
• Main Authors: Waldhoer, T, Klebermass-Schrehof, K
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01-09-2015; Nature Publishing Group
• Subjects: 692/499; Adolescent; Adult; Age; Altitude; Analysis; Austria - epidemiology; Birth Weight; Education; Educational Status; Female; Fetal Growth Retardation - epidemiology; Fetal Growth Retardation - etiology; Gestational Age; Health aspects; Health risk assessment; High altitude; High-altitude environments; Humans; Infant, Low Birth Weight; Infant, Newborn; Infants (Newborn); Male; Maternal Age; Medicine; Medicine & Public Health; Neonates; original-article; Pediatric Surgery; Pediatrics; Population studies; Population-based studies; Pregnancy; Regression analysis; Regression models; Reproductive History; Risk analysis; Risk Factors; Sex; Weight; Austria
• ISSN: 0743-8346; 1476-5543
• DOI: 10.1038/jp.2015.30

Objective:
A negative impact of altitude on birth weight has been demonstrated for medium to high-altitude countries.
Study Design:
The present study aims to show a similar effect for a lower altitude range up to 1600 m in the country of Austria and to adjust for several further risk factors related to mother and infant. In addition, we analyzed whether the effect of altitude influenced birth weight independently or interacted with other factors. For the purpose of this study, almost 1.9 million individual birth certificates of Austrian newborns born between 1984 and 2013 were analyzed. In a multivariate linear regression model, birth weight was associated with altitude of living address and following variables: sex, birth length, gestational age, level of education, maternal age, year of birth, parity, time to previous birth and marital status.
Result:
Birth weight decreased by 150 g/1000 m altitude, demonstrating a clear effect of altitude on birth weight also in a low to medium altitude level. Additionally, we could show that this effect also depends on other factors, namely gestational age, education of the mother, sex, birth length, year of birth and time to previous delivery. All variables interacted significantly (
p
<0.0001) with altitude.
Conclusion:
We observed a negative effect of altitude in an altitude range up to 1600 m. Furthermore, this effect also depends on other risk factors. Therefore, unadjusted estimates as described in many studies may be biased. This population-based study describes the effect of low-to-medium altitude on birth weight in central Europe over a period of 30 years.