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Background: Physical activity (PA) may influence fecundability through alterations in endocrine function. The limited studies that have evaluated PA and fecundability in non-clinical populations have utilized internet-based recruitment, contain potential issues in measurement, and have yielded inconclusive results. Methods: We evaluated the association between PA and time-to-pregnancy in the Effects of Aspirin in Gestation and Reproduction trial, which included 1228 women attempting pregnancy ages 18–40 with prior pregnancy loss. PA was measured at baseline using the short form of the International Physical Activity Questionnaire to determine hours/week of activity (vigorous, moderate, and walking) and hours/day of sedentary (sitting) behavior. Pregnancy was assessed using urine hCG assays. Discrete time Cox models were used to estimate fecundability odds ratios (FORs) adjusted for marital status and parity, accounting for left truncation and right censoring. Results: We observed a positive association between fecundability and vigorous PA of ≥ 4 hrs/week vs. none (FOR= 1.55, 95% CI: 1.17, 2.07) adjusted for marital status and parity. In stratified multivariable models, this association was most pronounced among overweight/obese women reporting vigorous PA of ≥ 4 hrs/week compared to none (FOR=2.27, 1.41, 3.65); however, there was no significant effect modification. Fecundability was not associated with categorical measures of moderate PA, walking, or sitting. Conclusion: In this study, fecundability was positively associated with vigorous PA. Further study is necessary to clarify possible mechanisms to explain the relationship through which vigorous PA might affect time-to-pregnancy; however, such improvements in fecundability may be related to a reduction in ovulatory disorders.

Daktaro disertacijos „Nėštumo laukimo laiką prognozuojančių veiksnių tyrimas“ tikslas - įvertinti nėštumo laukimo laiko sąsajas su demografiniais, socialiniais, gyvensenos, darbo, aplinkos ir genetiniais veiksniais ir sudaryti prognostinius jų įtakos modelius. Tyrimo uždaviniai: 1.Įvertinti demografinių, socialinių, gyvensenos, darbo ir gyvena–mosios aplinkos veiksnių sąsajas su nėštumo laukimo laiku. 2.Sudaryti svarbiausių demografinių, socialinių, gyvensenos, darbo ir gyvenamosios aplinkos veiksnių, kurie nulemia 12 mėnesių ir ilgesnį nėštumo laukimo laiką, prognostinį įvertinimo modelį. 3.Įvertinti FSH receptoriaus geno polimorfizmo variantų įtaką nėš–tumo laukimo laikui. 4.Sudaryti FSH receptoriaus geno polimorfizmo įtakos svarbiausiems demografiniams, socialiniams, gyvensenos, darbo ir gyvenamosios aplinkos veiksniams, kurie nulemia 12 mėnesių ir ilgesnį nėštumo laukimo laiką, prognostinį modelį. Nustatėme, kad svarbiausi nepriklausomi 12 mėnesių ir ilgesnį nėštumo laukimo laiką nulemiantys prognostiniai veiksniai yra 30 metų ir vyresnis amžius, anksčiau gydyti vaisingumo sutrikimai, ginekologinės ligos, kontracepcijos priemonių naudojimas iki nėštumo planavimo pradžios ir FSH receptoriaus geno SER/SER variantas, kurie pastojimo po 12 ir daugiau mėnesių tikimybę didino, atitinkamai, 1,95, 1,57, 2,21, 1,87 ir 1,68 kartus. / “Study of time to pregnancy prognostic factors”. The aim of the study was to investigate the relation between various factors and female fecundity, which was expressed as time to pregnancy (TTP) and to create prognostic models. Tasks of the study were: 1.Estimate the relation between socioeconomic, demographic, life-style, environmental and job-related factors and time to pregnancy; 2.Create prognostic valuation model for the most important social, demographic, life-style, environmental and job-related factors what are associated with 12 month or longer time to pregnancy; 3.Estimate the impact of FSH receptor gene polymorphism variant on time to pregnancy; 4.Create prognostic model for the most important factors what are associated with 12 month or longer time to pregnancy under the influence of FSH receptor gene polymorphism. We established, that the most important independent risk factors prognoses time to pregnancy of 12 or more months in women analyzed for FSH receptor gene polymorphism group were older age, having gynecological diseases or fertility problems in the past, the use of contraception prior to conception and SER/SER polymorphism variant, what increased the probability of conceiving after 12 or more months 1.95, 1.57, 2.21, 1.87 and 1.68 times respectively.

Cette thèse porte sur l’évaluation de l’impact de certains composés environnementaux sur la fécondité féminine, tel que mesuré par le délai de conception (« time to pregnancy » en anglais, ou TTP). Cette recherche a été réalisée dans le cadre de l’Étude mère-enfant sur les composés chimiques de l’environnement (MIREC), une cohorte de grossesse de 2001 femmes recrutées durant le premier trimestre dans dix villes canadiennes de 2008 à 2011. Les données des questionnaires et les échantillons biologiques ont servi à évaluer l’effet de deux groupes de composés : les persistants [composés perfluorés – perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA) et perfluorohexane sulfonate (PFHxS)] et les non persistants (bisphénol A, triclosan et phtalates). Cette thèse comprend également une analyse du potentiel du ratio index-annulaire (2D:4D) comme mesure de sensibilité endocrinienne. À ce jour, des mesures anthropométriques ont été collectées sur environ 800 mères-enfants dans le cadre de l’Étude mère-enfant sur les composés chimiques de l’environnement : biomonitoring et neurodéveloppement à la petite enfance (MIREC CD Plus), un suivi de la cohorte MIREC portant sur la croissance et le développement des enfants jusqu’à 5 ans. Sur l’ensemble, les résultats de cette thèse permettent d’étoffer les preuves concernant les effets adverses potentiels de plusieurs contaminants environnementaux sur la fécondité féminine, telle que mesurée par le TTP. Dans le premier article, nous avons montré une association entre les PFOA et les PFHxS et une baisse de fécondité, ce que d’autres recherches avaient déjà révélé. Dans le deuxième article, nous avons évalué l’effet du triclosan sur le TTP, ce qui n’avait jamais été examiné, pour montrer un délai plus élevé chez les femmes du quartile supérieur d’exposition. De plus, nos résultats sont en accord avec ceux de la seule étude ayant évalué l’effet du Bisphénol A sur la fécondité féminine, qui n’avait pas détecté d’effet. Finalement, nos données semblent indiquer une association entre l’exposition des femmes aux phtalates et un TTP plus court, mais ces résultats ne sont pas statistiquement significatifs. En ce qui a trait au potentiel du ratio index-annuaire (2D:4D) pour mesurer la sensibilité endocrinienne chez les femmes, nos données ne permettent pas d’établir une association entre ce ratio et le TTP. Pour ce qui est des enfants, nous n’avons pas trouvé d’effet adverse entre le tabagisme de la mère durant la grossesse et leur ratio 2D:4D. Par conséquent, nos données ne semblent pas justifier l’utilisation du ratio 2D:4D pour mesurer la sensibilité endocrinienne en lien avec le potentiel reproducteur (basé sur le TTP) ou l’exposition des enfants au tabac durant le premier trimestre de grossesse. / In this thesis, we aimed to evaluate the impact of selected environmental compounds on female fecundity as measured by time to pregnancy (TTP). This research was conducted in the framework of the Maternal-Infant Research on Environmental Chemicals (MIREC) study, a pregnancy cohort of 2001 women recruited during the first trimester of pregnancy in ten cities across Canada between 2008 and 2011. Questionnaire data and biological samples were analyzed to assess the effect of two groups of compounds: persistent [perfluorinated compounds - perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexane sulfonate (PFHxS)-] and nonpersistent chemicals (Bisphenol A, Triclosan, and phthalates). In addition, this thesis aimed to examine the potential of the second to fourth finger digit ratio (2D:4D) as a sensitive-endocrine endpoint. To this end, anthropometric measurements were obtained in about 800 children and their mothers during the Early Childhood Biomonitoring and Neurodevelopment Study (MIREC-CD Plus), a MIREC follow-up conducted to measure growth and development up to age five. Overall, the results of this thesis have contributed to the evidence regarding the potential adverse effect of several environmental contaminants (ECs) on female fecundity as measured by TTP. In the first article, we found that PFOA and PFHxS were associated with diminished fecundity, supporting previous evidence that suggested a similar effect. In the second article, we assessed for the first time the effect of Triclosan on TTP, presenting evidence of delayed fecundity at the highest quartile of exposure. In addition, our findings agreed with those of the only study that has assessed the effect of Bisphenol A on female fecundity, and which showed no effect. Finally, we found some indication that female exposure to phthalates might be associated with a shorter TTP, although this finding did not reach statistical significance. With regard to the potential of the digit length ratio (2D:4D) as an endocrine-sensitive endpoint in women, our data do not support a strong association between 2D:4D and TTP. In children, we did not find an adverse impact of maternal smoking during pregnancy on children’s 2D:4D. Thus, our data do not support evidence to suggest that 2D:4D could be used as a potential reproductive endocrine-sensitive endpoint in women as measured by TTP, and in their offspring as measured by exposure to maternal smoking during the first trimester of pregnancy.