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


Hum Reprod. 2020;35(4):816-825. 

In This Article


Participant Characteristics

Overall, 1727 (64.5%) of the 2679 participating couples conceived during follow-up. SnartForaeldre couples (N = 662) contributed 2475 menstrual cycles at risk and 450 pregnancies (68.0%), and PRESTO couples (N = 2017) contributed 7969 menstrual cycles at risk and 1277 pregnancies (63.3%). The median (interquartile range) of total male alcohol consumption was 4.5 (2.0–7.8) standard servings per week in SnartForaeldre and 4.1 (1.0–8.6) in PRESTO. The proportion of non-drinkers was 11.0% in SnartForaeldre and 20.4% in PRESTO. The proportions of male participants drinking ≥14 standard serving per week were 7.7% in SnartForaeldre and 13.9% in PRESTO. More men consumed beer (76.6%) than wine (48.7%) or spirits (43.7%). In total, 1598 (59.6%) men consumed a combination of two or more alcoholic beverages. Fewer men consumed only beer, wine or spirits (18.9, 2.6 and 3.4%, respectively).

Couples in SnartForaeldre and PRESTO had many similar characteristics, as shown in Table I. However, SnartForaeldre couples had a higher frequency of male physical activity, male sexually transmitted infections and infection in male reproductive organs than PRESTO couples. At the same time, men in PRESTO worked more hours per week, had a higher BMI and were more likely to consume soft drinks than men in SnartForaeldre. In both cohorts, caffeine consumption, regular smoking, female alcohol consumption and shorter attempt time at study entry were positively associated with male alcohol consumption, and men who previously had fathered a child were more likely to be non-drinkers. History of chronic disease ranged from 1.7% for diabetes to 12.3% for asthma and was not meaningfully associated with male alcohol consumption (data not shown). Overall, baseline characteristics were similar for couples with complete versus incomplete follow-up, except for couples lost to follow-up who were more likely to have shorter education, have lower income and be smokers (data not shown). Non-participating men were similar to participating men according to age and BMI, but more likely to be smokers (data not shown).

Alcohol Consumption and Fecundability

In pooled analyses, adjusted FRs for 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 (Table II). In cohort-stratified analyses, FRs in SnartForaeldre for 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. In PRESTO, FRs for 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. Similarly, the restricted cubic spline curve indicated little association between lower levels of alcohol consumption and fecundability (Figure 2). Starting at approximately 8.5 servings weekly, the spline curves show an inverse association between male alcohol consumption and fecundability in SnartForaeldre, but not in PRESTO.

Figure 2.

Association between male alcohol consumption and fecundability, examined using restricted cubic splines. Curves were adjusted for male and female age, female alcohol intake (continuous), frequency of intercourse, previously fathered a child, education, BMI, smoking, consumption of sugar-sweetened beverages and consumption of caffeine. PRESTO analyses were adjusted further for race/ethnicity. Five knots were located at 0, 3, 5, 10 and 18. CI: confidence interval.

In the pooled analysis (Table III), the relation between alcohol consumption and fecundability was similar across strata of attempt time at study entry, BMI and history of previously fathering a child. When we stratified by female age (<30 versus ≥30 years) and gravidity (yes versus no), alcohol consumption was slightly associated with decreased fecundability among older females and previous gravidity, though estimates were imprecise. In secondary analyses of the pooled data, in which we used a finer categorization of alcohol consumption, FRs for 14–20 and ≥21 standard servings per week compared with no alcohol consumption were 0.97 (95% CI: 0.79–1.21) and 0.99 (95% CI: 0.78–1.26), respectively.