Date Published: April 24, 2019
Publisher: Public Library of Science
Author(s): Aude-Marie Foucaut, Céline Faure, Chantal Julia, Sébastien Czernichow, Rachel Levy, Charlotte Dupont, Joël R. Drevet.
Physical activity (PA) and sedentary behavior have inconsistent effects on fertility. High body mass index is associated with infertility but to our knowledge, very few studies have explored body composition in association to fertility.
To assess the association between physical inactivity, sedentary behavior, body composition and idiopathic infertility in French men and women.
We conducted a case-control multicentric observational study. 159 infertile (79 men and 80 women) and 143 fertile (72 men and 71 women) were recorded in four fertility centers.
Participants completed self-administered questionnaires on sociodemographic and lifestyle characteristics, dietary intake, physical activity and sedentary behavior. Anthropometrics were measured, and bioelectrical impedance analysis was used to estimate body composition. Multivariable logistic regression was used to analyze the association of fertility with PA level and sedentary behavior.
In men, being physically inactive (Odd ratio [OR] 2.20; 95% confidence interval [CI], 1.06, 4.58) and having fat mass greater than the reference values for their age (OR 2.83; 95%CI, 1.31, 6.10) were positively associated with infertility. Sedentary behavior and fat-free mass were not related to infertility in men. In women, sedentary behavior (OR 3.61; 95%CI, 1.58, 8.24), high body fat (OR 3.16; 95%CI, 1.36, 7.37) and low fat-free mass (OR 2.65; 95%CI, 1.10, 6.37) were associated with infertility. PA level was not associated with fertility in women.
This study suggests that sedentary behavior and physical inactivity would represent two independent risk factors associated with infertility. The various elements that make up physical activity (frequency, intensity, time, and type of exercise) and the interrupting time spent sitting should be considered. Body composition variation should be explored further in relation to the biological pathways involved in idiopathic infertility. Moreover, the improvement of lifestyle factors should be considered in infertility treatment.
Sedentary behavior and physical inactivity represent major health concerns [1–3]. Sedentary behaviors are defined as any waking activities characterized by energy expenditure below 1.5 metabolic equivalent of task (MET) of sitting or lying down . Physical inactivity represents an insufficient volume of physical activity (PA) in daily life, being a level not reaching the recommended PA (150 minutes of moderate PA per week) . These two behaviors are in some cases coexistent, and sometimes not. Indeed, an individual may have both sedentary behaviors and be physically active [5,6]. In this case, PA can moderate but not offset the deleterious effects of sedentary behavior . It has been shown that sedentary behaviors and physical inactivity independently influence several health factors, non-communicable diseases and mortality [1–3,7,8].
Participants were recruited in the ALIFERT case-control multicentric observational study (“ALImentation et FERtilité”, ClinicalTrials.gov identifier: NCT01093378), which evaluated the associations between nutritional parameters and fertility among infertile and fertile couples. The institutional review board approved the study (ALIFERT study—national biomedical research P071224/AOM 08180: NEudra CT 2009-A00256-51).
Baseline characteristics of the 302 participants are presented in Table 1. Infertile participants were younger in comparison to fertile men and women (p = 0.006 and p = 0.02, respectively). They also had lower educational levels than fertile men and women (p = 0.005 in men and p = 0.0001 in women). The weight, BMI, waist circumference, hip circumference, and body fat of infertile men and women were significantly higher compared to fertile men and women. In men, the proportion of participants with metabolic syndrome was higher in infertile compared to fertile participants [12 (16.0%) vs. 3 (4.4%), respectively p = 0.03]. The proportion of normal weight obese did not differ between groups of fertile and infertile men [5 (6.9%) and 5 (6.3%), respectively, p = 1] and women [22 (31.0%) and 20 (25.0%), respectively, p = 0.5)]. Mean PA levels did not significantly differ between fertile and infertile men (2726.2 and 3291.2 MET-min/week, respectively, p = 0.7) and women (2632.8 and 2769.4 MET-min/week, respectively, p = 0.8). However, infertile men spent less time performing vigorous PA (37.6±48.6 min/week vs. 69.3±84.4 min/week, p = 0.006) in comparison to fertile men. Mean walking time was not different in infertile men compared to fertile men (42.3±73.8 min/week vs. 35.9±36.4 min/week, p = 0.2), nor in infertile women compared to fertile women (29.7±34.4 min/week vs. 46.6±66.5 min/week, p = 0.08). Physical activity was only inversely associated with sedentary behavior in infertile men (rPearson = -0.3, p = 0.04). Physical activity was only inversely associated with body fat percentage in fertile men (rPearson = -0.3, p = 0.03). All infertile and fertile participants followed nutritional guidelines similarly, with scores of 6.6±2.1 vs. 6.2±1.9, respectively, for men (p = 0.4), and scores of 6.3±2.9 vs. 6.3±3.1, respectively, for women (p = 0.9) (maximal possible score of 15). Based on PA guidelines, 34 (47.2%) and 50 (63.3%) (p = 0.05) fertile and infertile men did not follow PA guidelines (150 min/week of moderate-to-vigorous PA), respectively. Moreover, 43 (60.6%) and 55 (68.8%) (p = 0.3) fertile and infertile women were under the recommended PA level, respectively.
Idiopathic infertility in men and women may be related to lifestyle and body composition factors. In this case-control study, physical inactivity in men and sedentary behavior in women were independently associated with infertility. Body fat accumulation was significantly independently associated with infertility status in both men and women, while fat-free mass was related to infertility only in women.
The present study demonstrated that physical inactivity in men and sedentary behavior in women are associated with idiopathic infertility. Body fat accumulation has been related to infertility in both men and women, while fat-free mass was related to infertility in women only. This case-controlled study highlights that physical inactivity and sedentary behavior represent two independent risk factors for infertility. The effect of various elements that make up PA (i.e. FITT criteria) and interrupting the time spent sitting were not tested in this study, and should be considered in future research. The differences observed between men and women should also be studied further through multicentric interventional studies to better understand the lifestyle to promote to men and to women respectively. Moreover, body composition variation through lifestyle should be also explored further in relation to the biological pathways involved in idiopathic infertility. These findings suggest promoting and proposing a lifestyle supportive care during fertility treatment in order to improve pregnancy rates.