Tobacco, alcohol and fertility: the demonstrated effects

Tobacco: an established effect in women

Smoking accelerates the decline in ovarian reserve and brings forward the age of menopause. It is associated with a longer time to conception, an increased risk of miscarriage and ectopic pregnancy, and poorer assisted reproduction outcomes.

Passive smoking is also involved. Quitting improves the situation, even after many years of smoking.

Tobacco: an established effect in men

In men, smoking is associated with lower sperm concentration and motility, more morphological abnormalities and increased sperm DNA fragmentation. These parameters generally improve after quitting, since spermatogenesis renews itself over roughly three months.

Alcohol: an established effect at high intake

High alcohol intake is associated with ovulation disorders in women and with lower testosterone and poorer semen quality in men. In assisted reproduction, heavy intake is associated with poorer outcomes.

Alcohol: more nuanced data at moderate intake

At low or moderate intake, study results are heterogeneous and do not support a firm conclusion about time to conception. This uncertainty applies only to the trying-to-conceive period: in pregnancy, the official recommendation is complete abstinence, as no risk-free threshold has been established for the fetus.