Parents' smoking onset before conception as related to body mass index and fat mass in adult offspring: Findings from the RHINESSA generation study

• Published in: PLOS ONE
• Main Authors: Knudsen, Gerd Toril Mørkve, Dharmage, Shyamali C., Janson, Christer, Abramson, Michael J., Benediktsdóttir, Bryndís, Malinovschi, Andrei, Skulstad, Svein Magne, Bertelsen, Randi Jacobsen, Gómez Real, Francisco, Schlünssen, Vivi, Jõgi, Nils Oskar, Sánchez-Ramos, José Luis, Holm, Mathias, García Aymerich, Judith, Forsberg, Bertil, Svanes, Cecilie, Johannessen, Ane
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS)
• Subjects: Smoking habits; Body mass index; Adipose tissue; Obesity; Educational attainment; Body weight; Linear regression analysis; Medical risk factors; Bergen; Norway; Iceland
• Online Access: http://hdl.handle.net/10230/46262; https://doi.org/10.1371/journal.pone.0235632

Emerging evidence suggests that parents' preconception exposures may influence offspring health. We aimed to investigate maternal and paternal smoking onset in specific time windows in relation to offspring body mass index (BMI) and fat mass index (FMI). We investigated fathers (n = 2111) and mothers (n = 2569) aged 39-65 years, of the population based RHINE and ECRHS studies, and their offspring aged 18-49 years (n = 6487, mean age 29.6 years) who participated in the RHINESSA study. BMI was calculated from self-reported height and weight, and FMI was estimated from bioelectrical impedance measures in a subsample. Associations with parental smoking were analysed with generalized linear regression adjusting for parental education and clustering by study centre and family. Interactions between offspring sex were analysed, as was mediation by parental pack years, parental BMI, offspring smoking and offspring birthweight. Fathers' smoking onset before conception of the offspring (onset ≥15 years) was associated with higher BMI in the offspring when adult (β 0.551, 95%CI: 0.174-0.929, p = 0.004). Mothers' preconception and postnatal smoking onset was associated with higher offspring BMI (onset <15 years: β1.161, 95%CI 0.378-1.944; onset ≥15 years: β0.720, 95%CI 0.293-1.147; onset after offspring birth: β2.257, 95%CI 1.220-3.294). However, mediation analysis indicated that these effects were fully mediated by parents' postnatal pack years, and partially mediated by parents' BMI and offspring smoking. Regarding FMI, sons of smoking fathers also had higher fat mass (onset <15 years β1.604, 95%CI 0.269-2.939; onset ≥15 years β2.590, 95%CI 0.544-4.636; and onset after birth β2.736, 95%CI 0.621-4.851). There was no association between maternal smoking and offspring fat mass. We found that parents' smoking before conception was associated with higher BMI in offspring when they reached adulthood, but that these effects were mediated through parents' pack years, suggesting that cumulative smoking exposure during offspring's childhood may elicit long lasting effects on offspring BMI. Co-ordination of the RHINESSA study has received funding from the Research Council of Norway (Grants No. 274767, 214123, 228174, 230827 and 273838), ERC StG project BRuSH #804199, the European Union's Horizon 2020 research and innovation program under grant agreement No. 633212 (the ALEC Study WP2), the Bergen Medical Research Foundation, and the Western Norwegian Regional Health Authorities (Grants No. 912011, 911892 and 911631). Study centres have further received local funding from the following: Bergen: the above grants for study establishment and co-ordination, and, in addition, World University Network (RDF and Sustainability grant), Norwegian Labour Inspection, and the Norwegian Asthma and Allergy Association. Albacete and Huelva: SEPAR. Fondo de Investigación Sanitaria (FIS PS09). Gøteborg, Umeå and Uppsala: the Swedish Lung Foundation, the Swedish Asthma and Allergy Association. Reykjavik: Iceland University. Melbourne: NHMRC, Melbourne University, Tartu: the Estonian Research Council (Grant No. PUT562). Århus: The Danish Wood Foundation (Grant No. 444508795), the Danish Working Environment Authority (Grant No. 20150067134). The RHINE study received funding by Norwegian Research Council, Norwegian Asthma and Allergy Association, Danish Lung Association, Swedish Heart and Lung Foundation, Vårdal Foundation for Health Care Science and Allergy Research, Swedish Asthma and Allergy Association, Swedish Lung Foundation, Icelandic Research Council, and Estonian Science Foundation. The co-ordination of ECRHS was supported by European Union's Horizon 2020 research and innovation program under grant agreement No. 633212 (the ALEC Study), the European Commission frameworks 5 and 7 (ECRHS I and II) and the Medical Research Council (ECRHS III).