Male Alcohol Consumption and Fecundability

S. Høyer; A.H. Riis; G. Toft; L.A. Wise; E.E. Hatch; A.K. Wesselink; K.J. Rothman; H.T. Sørensen; E.M. Mikkelsen

Disclosures

Hum Reprod. 2020;35(4):816-825. 

In This Article

Abstract and Introduction

Abstract

Study Question: Does male alcohol consumption affect fecundability?

Summary Answer: In data pooled across Danish and North American preconception cohort studies, we found little evidence of an association between male alcohol consumption and reduced fecundability.

What is Known Already: Experimental and clinical studies have shown that alcohol affects male reproductive physiology, mainly by altering male reproductive hormones and spermatogenesis. However, few epidemiologic studies have examined the association between alcohol consumption and male fertility.

Study Design, Size, Duration: Data were collected from two ongoing prospective preconception cohort studies: the Danish 'SnartForaeldre' (SF) study (662 couples) and the North American 'Pregnancy Study Online' (PRESTO) (2017 couples). Participants included in the current analysis were enrolled from August 2011 through June 2019 (SF) and from June 2013 through June 2019 (PRESTO).

Participants/Materials, Setting, Methods: Eligible men were aged ≥18 years in SF and ≥21 years in PRESTO, in a stable relationship with a female partner and not using contraception or receiving fertility treatment. In both cohorts, alcohol consumption/serving size was self-reported as number of beers (330 mL/12 oz.), glasses of white or red wine (120 mL/4 oz. each), dessert wine (50 mL/2 oz.) and spirits (20 mL/1.5 oz.). Overall alcohol consumption was categorized as none, 1–5, 6–13 and ≥14 standard servings per week. Total menstrual cycles at risk were calculated using data from female partners' follow-up questionnaires, which were completed every 8 weeks until self-reported pregnancy or 12 menstrual cycles, whichever came first. Analyses were restricted to couples that had been trying to conceive for ≤6 cycles at study entry. Proportional probability regression models were used to compute fecundability ratios (FRs) and 95% confidence interval (CIs). We adjusted for male and female age, female partner's alcohol consumption, intercourse frequency, previous history of fathering a child, race/ethnicity, education, BMI, smoking and consumption of sugar-sweetened beverages and caffeine.

Main Results and the Role of Chance: The cumulative proportion of couples who conceived during 12 cycles of follow-up were 1727 (64.5%). The median (interquartile range) of total male alcohol consumption was 4.5 (2.0–7.8) and 4.1 (1.0–8.6) standard servings per week in the SF and PRESTO cohorts, respectively. In pooled analyses, adjusted FRs for male alcohol consumption of 1–5, 6–13 and ≥14 standard servings per week compared with no alcohol consumption were 1.02 (95% CI: 0.90–1.17), 1.10 (95% CI: 0.96–1.27) and 0.98 (95% CI: 0.81–1.18), respectively. For SF, adjusted FRs of 1–5, 6–13 and ≥14 standard servings per week compared with no alcohol consumption were 0.97 (95% CI: 0.73–1.28), 0.81 (95% CI: 0.60–1.10) and 0.82 (95% CI: 0.51–1.30), respectively. For PRESTO, adjusted FRs of 1–5, 6–13 and ≥14 standard servings per week compared with no alcohol consumption were 1.02 (95% CI: 0.88–1.18), 1.20 (95% CI: 1.03–1.40) and 1.03 (95% CI: 0.84–1.26), respectively.

Limitations, Reasons for Caution: Male alcohol consumption was ascertained at baseline only, and we did not distinguish between regular and binge drinking. In addition, we had insufficient numbers to study the effects of specific types of alcoholic beverages. As always, residual confounding by unmeasured factors, such as dietary factors and mental health, cannot be ruled out. Comorbidities thought to play a role in the reproductive setting (i.e. cancer, metabolic syndrome) were not considered in this study; however, the prevalence of cancer and diabetes was low in this age group. Findings for the highest categories of alcohol consumption (6–13 and ≥14 servings/week) were not consistent across the two cohorts.

Wider Implications of the Findings: Despite little evidence of an association between male alcohol consumption and reduced fecundability in the pooled analysis, data from the Danish cohort might indicate a weak association between reduced fecundability and consumption of six or more servings per week.

Study Funding/Competing Interest(S): This study was supported by the National Institutes of Health (R01-HD060680, R01-HD086742, R21-HD050264, R21-HD072326, R03-HD090315), the Novo Nordisk Foundation, Oticon Fonden, Politimester J.P.N. Colind og hustru Asmine Colinds mindelegat and Erna og Peter Houtveds studielegat. PRESTO receives in-kind donations from FertilityFriend.com, Kindara.com, Swiss Precision Diagnostics and Sandstone Diagnostics for the collection of data pertaining to fertility. Dr Wise serves as a consultant on uterine leiomyomata for AbbVie.com. All other authors declare no conflict of interest.

Introduction

In developed countries, infertility affects up to 15% of couples (Slama et al., 2012, Thoma et al., 2013). The distress experienced by infertile couples and the increasing demand for ART (Kupka et al., 2014) have led to a greater focus on elucidating modifiable risk factors for infertility. In Western nations, a decline in sperm count has been observed over the last 40 years (Levine et al., 2017), and male factors contribute to infertility in approximately 50% of all cases (Irvine et al., 1998).

Potential modifiable risk factors for male infertility include lifestyle factors such as smoking (Soares and Melo, 2008; Harlev et al., 2015), obesity (Wise et al., 2010; Sundaram et al., 2017) and intake of sugar-sweetened beverages (Hatch et al., 2018); the impact of alcohol consumption is less clear. Alcohol consumption is a habitual part of daily life for a large proportion of males of reproductive age (WHO, 2014). In several countries, official guidelines recommend that men limit their consumption of alcohol to a maximum of 14 drinks per week, with no distinction made for men actively trying to conceive (Danish National Board of Health, 2015; The U.S. Department of Health and Human Services and the U.S. Department of Agriculture, 2015).

Previous studies have shown that alcohol affects the male reproductive system by altering the regulation of the hypothalamic–pituitary–gonadal (HPG) axis and spermatogenesis. Most studies of healthy young men have found higher alcohol consumption to be positively associated with testosterone levels and inversely associated with sex hormone-binding globulin levels (Shiels et al., 2009; Hansen et al., 2012; Jensen et al., 2014a; Jensen et al., 2014b). In contrast, decreased testosterone levels, and elevated levels of FSH and LH have been observed among alcoholic men, indicating that alcohol abuse may impair the HPG axis or cause Leydig-cell damage (Emanuele, 1998; Muthusami and Chinnaswamy, 2005; Maneesh et al., 2006).

Alcohol consumption also has been inversely associated with total sperm count, sperm concentration and percentage of morphologically normal sperm (Emanuele, 1998; Muthusami and Chinnaswamy, 2005; La Vignera et al., 2013; Jensen et al., 2014; Borges et al., 2018). Other studies have reported a positive association between moderate male alcohol consumption and semen quality (Ricci et al., 2018).

One cohort study found that male alcohol consumption was associated with shorter time to pregnancy (TTP) (Florack et al., 1994), whereas two other cohort studies found a weak association with longer TTP (Curtis et al., 1997; Olsen et al., 1997). Thus, the extent to which male alcohol consumption influences TTP is unclear. In the present study, we examined the association between male alcohol consumption and couples' TTP in two prospective cohort studies of Danish and North American couples.

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