Birth- and childhood-related characteristics with an important and notable influence on lung function in early adulthood include maternal perinatal body mass index (BMI), birth weight, childhood lean/fat mass, and early-onset asthma, according to study findings published in the European Respiratory Journal.
Researchers sought to determine the relative importance of characteristics related to birth, childhood, and adolescence with respect to their level of effect on lung function in early adult life, using data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a British population-based birth cohort.
The birth cohort included 14,062 children born in the early 1990s in Avon, United Kingdom who were prospectively monitored. For the current study, the “study population” was defined by researchers as the 7545 birth cohort members (96.3% White; 51% female) who had at least 1 spirometry measurement taken at 8, 15, or 24 years of age. The investigators compared the characteristics of the study population with those of the original cohort. The researchers also compared participants in the study population with (n=2800) and without (n=4745) lung function measurements at age 24 years.
The researchers evaluated 33 sociodemographic, environmental, lifestyle, and physiologic characteristics that are considered risk factors for low lung function. These characteristics were clustered into 5 categories: (1) demographic, maternal, and child; (2) perinatal; (3) postnatal; (4) early childhood; and (5) adolescence.
After standardizing expected lung function measurements according to sex, age, and height, the researchers calculated the association between each characteristic and the variance between standard and actual lung function measures.
Spirometry measurements were obtained for 88%, 51%, and 37% of participants at ages 8, 15, and 24 years, respectively. Similar results were observed in characteristics for the original ALSPAC cohort and the study population regarding observed and imputed data, and for participants with and without lung function measurements at age 24 years. Lung function outcomes at age 24 years were similar for observed and imputed data.
After adjustment for sex, age, and height, the proportions of remaining variance in lung function parameters accounted for by the characteristics that were analyzed (R2 of standard deviation-score models) were 10.8%, 6.7%, 3.5%, and 2.4% for forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, and forced mid-expiratory flow (FEF25-75), respectively.
Perinatal and early childhood characteristics had the greatest effect in variations of all lung function parameters, compared with other life stages. Regarding FVC, maternal perinatal BMI, birthweight, lean mass, and fat mass at age 9 years had a relative importance (RI) of 0.6%, 0.5%, 7.7%, and 0.6%, respectively. The characteristic of most relative importance for FEV1 were parity (RI=0.5%), birthweight (RI=0.5%), lean mass (RI=4.6%), and fat mass (RI=0.5%).
Maternal perinatal BMI (RI=0.5%), maternal smoking during pregnancy (RI=0.5%), lean mass (RI=0.8%), and asthma at age 7.5 years (RI=0.6%) had the greatest RI for FEV1/FVC. Asthma had the greatest effect on FEF25-75 (RI=0.7%).
In analyses limited to participants with measured (nonimputed) lung function at age 24 years, similar results were observed regarding the associations and relative importance with lung function.
Study limitations include the risk of confounding, some missing data, and potential residual confounding by unmeasured characteristics such as diet and physical activity that were only available for a small number of participants.
“Our findings highlight the importance of early-life characteristics in lung function and suggest public health polices targeting modifiable risk factors in childhood may improve maximally attained lung function and minimize poor respiratory health in later life,” stated the investigators.
Mahmoud O, Granell R, Peralta GP, et al. Early-life and health behaviour influences on lung function in early-adulthood. Eur Respir J. Published online February 2, 2023. doi:10.1183/13993003.01316-2020