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oai:recercat.cat:20.500.14342/45782025-05-15T19:20:24Zcom_2072_482405com_2072_183628col_2072_482409

Smoking and infertility: multivariable regression and Mendelian randomization analyses in the Norwegian Mother, Father and Child Cohort Study Hernáez, Álvaro Wootton, Robyn E. Page, Christian Magnus Skåra, Karoline Hansen Fraser, Abigail Rogne, Tormod Magnus, Per Njølstad, Pål R. Andreassen, Ole A. Burgess, Stephen Lawlor, Deborah A. Magnus, Maria Christine Universitat Ramon Llull. Facultat de Ciències de la Salut Blanquerna Hàbit de fumar Esterilitat Aleatorització Mendeliana Objective To investigate the association between smoking and infertility. Design Prospective study. Setting Nationwide cohort. Patients 28,606 women and 27,096 men with questionnaire and genotype information from the Norwegian Mother, Father, and Child Cohort Study. Intervention Self-reported information on smoking (having ever smoked [both sexes], age at initiation [women only], cessation [women only], and cigarettes/week in current smokers [both sexes]) was gathered. Genetically predetermined levels or likelihood of presenting these traits were estimated for Mendelian randomization. Main outcome measure Infertility (time-to-pregnancy ≥12 months). Results Having ever smoked was unrelated to infertility in women or men. Higher smoking intensity in women was associated with greater infertility odds (+1 standard deviation [SD, 48 cigarettes/week]: odds ratio [OR]crude, 1.19; 95% confidence interval [CI] 1.11–1.28; ORadjusted 1.12; 95% CI, 1.03–1.21), also after adjusting for the partner’s tobacco use. Later smoking initiation (+1 SD [3.2 years]: ORcrude, 0.94; 95% CI, 0.88–0.99; ORadjusted 0.89; 95% CI, 0.84–0.95) and smoking cessation (vs. not quitting: ORcrude, 0.83; 95% CI, 0.75–0.91; ORadjusted, 0.83; 95% CI, 0.75–0.93) were linked to decreased infertility in women. Nevertheless, Mendelian randomization results were not directionally consistent for smoking intensity and cessation and were estimated imprecisely in the 2-sample approach. In men, greater smoking intensity was not robustly associated with infertility in multivariable regression and Mendelian randomization. Conclusions We did not find robust evidence of an effect of smoking on infertility. This may be due to a true lack of effect, weak genetic instruments, or other kinds of confounding. Tabaquismo e infertilidad: regresión multivariable y análisis de aleatorización mendeliana en el estudio de cohorte noruego de madre, padre e hijo. info:eu-repo/semantics/publishedVersion 2022-07 info:eu-repo/semantics/article http://hdl.handle.net/20.500.14342/4578 https://doi.org/10.1016/j.fertnstert.2022.04.001 eng Fertility and Sterility, 2022, 118(1): 180-190 info:eu-repo/grantAgreement/EU/H2020/Grant agreement 947684 © L'autor/a Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess 11 p. Elsevier