Do Soft Drinks Reduce Fertility?
Yes -- women drinking 7+ sugar-sweetened drinks per week had a 25% lower monthly chance of conceiving, and men drinking that much had a 33% lower chance of getting their partner pregnant, even after adjusting for BMI, caffeine, smoking, and sex frequency. Diet sodas showed no such effect.
It's probably no surprise that sugary drinks aren't great for your health -- but does that extend to fertility specifically? A group of researchers set out to find out.
The study
About 4,000 women completed questionnaires from the point they started trying to conceive (within 6 months) up until a year later or until they became pregnant, whichever came first. Male partners also filled out surveys on their own diet and lifestyle.
What they found
Women drinking 1 or more sugar-sweetened beverages per day (7+ per week) were on average 2 years younger than women who drank none -- yet still had a harder time getting pregnant, with a 25% lower chance of conceiving in any given month, even after adjusting for BMI, caffeine intake, smoking, and how often couples had sex. For men, the effect was worse: men drinking 7+ sugary beverages a week were linked to a 33% lower monthly chance of getting their partner pregnant. Men consuming more than one sugar-sweetened energy drink a day specifically showed a 56% lower chance -- though that figure came from a small number of men in the study, so it's less certain. These findings line up with other research linking sugary beverage consumption to lower sperm motility and semen volume in men.
Notably, this study found no negative effect from diet sodas -- pointing the researchers toward sugar itself, rather than something like BPA leaching from cans, as the likely mechanism. So if you needed a reason to cut back on sugary drinks -- for yourself or a partner who has a habit -- this is a solid one.
References
Hatch et al. (2018). Epidemiology. Intake of Sugar-sweetened Beverages and Fecundability in a North American Preconception Cohort. Chiu et al. (2014). Human Reproduction, 29(7), 1575–1584. Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men. Yang et al. (2015). Medicine, 94(28), e1166. Lifestyles Associated With Human Semen Quality: Results From the MARHCS Cohort Study in Chongqing, China.
Common questions
Does this apply to diet soda too?
No -- this study found no negative effect from diet sodas specifically, which pointed researchers toward sugar itself (rather than something like BPA from cans) as the likely culprit.
Does it matter if it's my male partner drinking the sugary sodas?
Yes, and the effect was actually larger for men in this study -- a 33% lower monthly chance of pregnancy for men drinking 7+ a week, versus 25% for women.