For him: what the future father can do
Smoking, alcohol, heat, weight, age: what matters on the future father's side, and why the changes he makes show up about three months later.
For him: what the future father can do
A baby is something you plan as two. Much of the advice is aimed at women, but the future father's health matters too. Here's what research and health authorities say, written so you can read it and then share it if you'd like. This article contains no data about your cycle.
Why "in about 3 months"
Sperm aren't made overnight. A landmark study published in Science in 1963 estimated that their full development takes about 64 days. A more recent study, which tracked sperm production in healthy men, found an average of 64 days, ranging from 42 to 76 days depending on the man.
In practice: what he changes today shows up in his sperm about two months later, sometimes a little more. Allowing about 3 months is a reasonable margin. In other words, what he changes now counts for the months ahead.
Smoking
According to the Assurance Maladie (France's national health insurance), smoking affects male reproductive function at several levels and reduces sperm count and quality. The NHS sums it up: smoking reduces semen quality. And quitting matters for you too: France's national health authority (HAS) advises couples to stop smoking before pregnancy, and the Assurance Maladie advises removing exposure to second-hand smoke.
Cannabis, for its part, reduces sperm volume and count, according to the Assurance Maladie.
Alcohol
Alcohol impairs male fertility and has a so-called epigenetic toxicity on sperm, the Assurance Maladie states. Santé publique France, the French public health agency, notes that ethanol causes changes in sperm, in an article titled "Paternal alcohol use, a risk for the foetus too". NICE notes that excessive alcohol intake is detrimental to semen quality. As a guide, the NHS advises men to drink no more than 14 UK units of alcohol a week, spread over at least 3 days.
Weight
In men who are overweight, the Assurance Maladie describes an excess of oestrogen (hyperoestrogenism) and a lower sperm count. According to NICE, men with a BMI of 30 or more are also likely to have reduced fertility. Moving more and eating better is something you can do together, without pressure.
Heat
The NHS notes a link between a higher temperature of the scrotum and reduced semen quality. It adds, however, that it's uncertain whether wearing loose-fitting underwear improves fertility. Avoiding long exposure to heat costs nothing, but there's no need to obsess over it.
Age
Fathers are getting older on average (34.1 years according to the Assurance Maladie), and the genetic material of sperm changes with age. A major review published in The Lancet in 2021 also lists a father's age over 40 among the risk factors for miscarriage. It's not a reason to worry: it's a reason not to leave his health out of the plan.
Work and environment
The NHS advises limiting exposure to pesticides, solvents and metals, which can affect fertility. The Assurance Maladie also mentions endocrine disruptors. If he's exposed to them at work, he can talk to his doctor or occupational health service.
Health checks
- Medicines: the NHS advises seeing a doctor sooner if you take prescribed or over-the-counter medicines. He can discuss this with his doctor.
- Vaccinations: since 2022 the first recommended measure in France is whooping cough vaccination of the pregnant woman, from the second trimester. If that could not happen, or happened less than a month before birth, vaccination of those close to the newborn, the father included, is recommended: this is known as cocooning. His doctor can tell him where he stands.
- Testing: the HAS suggests offering HIV testing to the couple, and if you're rhesus negative, it helps to know the future father's blood group.
If pregnancy takes a while
Fertility assessment involves both partners. For the Assurance Maladie, a semen analysis is essential, because it identifies most causes of male infertility. It's advised to seek help after 12 months of trying, or after 6 months if you're over 35, and sooner if either of you has a known health issue that could affect fertility.
To share
You can let him read this article as it is. The idea isn't to hand him a to-do list, but to remind you both that this is a plan you carry together, and that it's not up to you alone to think about it.
This article is for information only. Lovae is not a medical device and does not replace medical advice. For any question, the future father can talk to his GP.
Sources
- Ameli · Declining fertility and fecundity: why? (in French)
- Vaccination Info Service (Santé publique France) · Grossesse et projet de grossesse : vaccination contre la coqueluche
- Santé publique France · Paternal alcohol use, a risk for the foetus too (in French) (2026)
- NHS · Infertility
- NHS · Infertility: causes
- NHS · Trying to get pregnant
- British Journal of General Practice · Assessment and treatment for people with fertility problems: NICE guideline (O'Flynn, 2014)
- Science · Spermatogenesis in man: an estimate of its duration (Heller and Clermont, 1963)
- The Journal of Urology · A stable isotope-mass spectrometric method for measuring human spermatogenesis kinetics in vivo (Misell et al., 2006)
- The Lancet · Miscarriage matters: the epidemiological, physical, psychological, and economic costs of early pregnancy loss (Quenby et al., 2021)
- HAS · Pregnancy planning: information, prevention messages and tests to offer (in French)
- Ameli · Medical fertility assessment (in French)
Official sources, accessed in September 2026.