Which Habits Actually Affect Fertility?

Four habits have real evidence behind them: smoking, heavy alcohol use, high caffeine intake and recreational drug use are all associated with reduced fertility, and the American Society for Reproductive Medicine advises reducing alcohol and caffeine and avoiding smoking and recreational drugs while trying to conceive. Body weight at either extreme also matters. Beyond those, much of what circulates about lifestyle and fertility is not supported, and the single largest factor, age, is not a habit at all.

Smoking

The clearest of the modifiable factors, and it affects both partners. ASRM's fact sheet on smoking and infertility sets out the effects, and its committee opinion on tobacco or marijuana use covers e-cigarettes and marijuana alongside conventional smoking.

Secondhand exposure counts, so a household where one partner still smokes leaves the other affected. Our article on smoking, vaping and fertility covers this in detail.

Alcohol

ASRM advises reducing alcohol while trying to conceive, for both partners. In men it is associated with poorer semen parameters; in women, with reduced fertility. It is also worth stopping ahead of a pregnancy rather than on confirmation of one, since the early weeks matter and are often the ones before a pregnancy is known.

Caffeine

High intake is associated with reduced fertility and ASRM advises reducing it. The commonly used limit while trying to conceive or pregnant is 200 mg a day, which is roughly two cups of coffee, though caffeine content varies considerably between drinks. Check what your own doctor advises rather than counting cups.

Body weight

Weight at either extreme affects the hormonal signals that drive ovulation, so both being significantly overweight and being significantly underweight can disrupt cycles. In men, obesity is associated with poorer semen parameters. This is one of the modifiable factors with a genuine bearing on outcomes, and it is also one where changes take time.

Heat exposure, for men

Sperm production is temperature sensitive, which is why sustained heat, from hot baths, saunas or similar, is commonly advised against when trying to conceive or before a semen analysis.

What about stress?

Trying to conceive is stressful and managing that is worth doing for its own sake. Be cautious of confident claims that stress causes infertility or prevents implantation. The evidence does not support stating it that firmly, and doing so makes people feel responsible for an outcome they did not control. If you have been trying for twelve months, an assessment is more useful than further stress management.

What about the contraceptive pill?

The pill does not reduce your long-term fertility, however long you take it. Fertility returns after stopping and there is no accumulating effect from years of use. Our article on the pill and fertility covers this. Any advice to limit pill use to a set number of years for fertility reasons should be treated with caution.

What matters more than any of these?

Age, and it is not a behavior. The American College of Obstetricians and Gynecologists sets out how aging affects fertility and pregnancy. Underlying conditions such as blocked tubes, endometriosis, PCOS or a male factor also outweigh lifestyle, and none of them respond to habit change.

That is the practical point of this article. Lifestyle changes are worth making and they are not a substitute for finding out what is actually going on. The NICE guideline on fertility problems sets the usual threshold for assessment at twelve months, with earlier assessment where the woman is 36 or over.

We at Millennium IVF Clinic assess both partners. You can arrange a consultation with our team.

Frequently asked questions

How long before trying should I change these habits?

For men there is a practical marker: sperm production takes roughly two to three months, so changes need at least that long to show. For women, earlier is simply better.

Can lifestyle changes alone fix infertility?

They can improve a borderline situation. They do not resolve blocked tubes, endometriosis, a structural or genetic male factor, or age-related decline.

Is it too late if I have smoked for years?

Stopping is still worthwhile. For men, sperm quality can improve within about three months. For women, damage to the ovarian reserve is not reversed, which is a reason to stop sooner rather than a reason not to bother.

Does my partner's lifestyle matter as much as mine?

Yes. Male factors are involved in a substantial proportion of cases, and smoking, alcohol, weight and heat exposure all affect semen quality.