Preconception Care: Small Choices, Big Impacts On Fertility

When you and your partner decide to try for a baby, the health journey begins before conception. Your habits in the months leading up—what you eat, drink, inhale, and use on your body—can influence not only whether conception happens, but also embryo quality, pregnancy outcome, and even your child’s long-term health. The good news? There are actionable changes you can make now that are supported by peer-reviewed evidence.

How Alcohol, Caffeine, and Smoking Affect Fertility

Alcohol

• Drinking alcohol, especially more than seven drinks per week, has been associated with reduced odds of becoming pregnant in couples undergoing fertility treatments like IVF and ICSI. Harvard Health

• Even moderate drinking in the second half of the menstrual cycle (luteal phase) appears to reduce the probability of conception. In a prospective study of over 400 women, three to six drinks per week during the luteal phase were linked to lower conception rates compared to non-drinkers. UofL

• Paternal alcohol consumption has also been associated with increased risk of birth defects in offspring, likely through epigenetic effects on sperm.

Caffeine

• The research on caffeine is mixed. Some large observational studies found no strong association between moderate caffeine consumption and lower IVF or pregnancy success. For instance, in the Harvard Health review, caffeine consumption by women or their male partners was not significantly tied to reduced live births in IVF, unlike alcohol. Harvard Health

• That said, very high caffeine intake (often exceeding 300-400 mg/day) has been suggested in some studies to increase miscarriage risk or delay conception. Because individual sensitivity varies, many preconception guidelines suggest limiting caffeine to below 200 mg/day (about 1-2 regular cups of coffee). (Note: this limit is often suggested in practice rather than definitively proven in all studies.)

Smoking (Tobacco & Marijuana)

• Tobacco: Numerous studies show that smoking reduces fertility in both men and women via effects on sperm count and motility, egg quality, ovarian reserve, increased risk of miscarriage, and poorer outcomes in assisted reproduction.

• Marijuana: While research is still emerging, there is growing evidence that THC use can impair sperm function (motility, morphology) and affect ovulation cycles in women. Because epigenetic and endocrine disruption from smoke exposure (including marijuana) is biologically plausible, it’s wise to minimize or avoid use in the preconception period.

Healthy Swaps You Can Start Now

Little changes in daily life can add up. Here are research-supported swaps to protect fertility:

Swap	Why It Matters
Replace soda or sugary drinks with sparkling water or water infused with fruit.	Lower sugar load helps reduce insulin spikes and inflammation, both of which can negatively affect fertility.
Use olive or avocado oil instead of refined seed oils	Rich in monounsaturated fats and antioxidants, which are anti-inflammatory and help improve ovulation and hormone balance.
Cook at home instead of relying on fast food.	Processed & ultra-processed foods often have trans fats, high sugar, and additives that may harm fertility. Home-cooked food allows you to control quality.
Avoid plastic containers & non-stick cookware.	Plastics often contain BPA or phthalates — known endocrine disruptors that may affect egg & sperm quality.
Switch perfume/air fresheners with synthetic fragrance → essential-oil based / unscented.	Some synthetic fragrances use phthalates, which have been linked in observational studies to reproductive hormone disruption.

Why the Mediterranean Diet is a Fertility Game Changer

Multiple studies show that adhering to a Mediterranean dietary pattern is associated with better fertility outcomes.

• A 2018 study of non-obese women trying IVF found that those with higher adherence to the Mediterranean diet had higher live birth and clinical pregnancy rates. Oxford Academic

• In a 2019 prospective cohort study, women following the Mediterranean diet had improved embryo yield in IVF cycles. PMC

• A systematic review (2022) looked at several dietary patterns, including Mediterranean, ‘profertility,’ and preconception diets; higher adherence to these diets was associated with increased probability of pregnancy or live birth in some studies. However, researchers note that methodologies vary and causation is not fully established. BioMed Central

Key components of the Mediterranean diet that appear especially beneficial include:

• High intake of vegetables, fruits, legumes, nuts, and whole grains

• Use of olive oil as the primary fat

• Moderate consumption of fish (especially fatty fish)

• Low consumption of processed foods, sugary drinks, and red/processed meats

Preconception care isn’t about perfection—it’s about preparation. What you eat, drink, inhale, and surround yourself with in the months before conception can influence pregnancy, embryo quality, and your child’s lifelong health. By reducing harmful exposures, limiting alcohol and smoking, making thoughtful dietary choices, and embracing fertility-supporting patterns like the Mediterranean diet, you set up the healthiest possible start for yourself, your partner, and your future baby.

References

1. Baroutis, D., et al. (2024). The Role of the Mediterranean Diet in Assisted Reproduction. PMC. PMC

2. Sun, H., et al. (2019). Mediterranean diet improves embryo yield in IVF: a prospective cohort study. Reproductive Biology and Endocrinology, 17:73. PMC

3. Karayiannis, D., Kontogianni, M.D., et al. (2018). Adherence to the Mediterranean diet and IVF success rate among non-obese women. Human Reproduction, 33(3):494-502. Oxford Academic

4. Sanderman, E.A., et al. (2022). Female dietary patterns and outcomes of in vitro fertilization. Nutrition Journal. BioMed Central

5. Mikkelsen, E.M., et al. (2016). Alcohol consumption and fecundability: prospective Danish cohort study. PMC. PMC

6. Lee, Y.J., et al. (2020). Alcohol consumption before pregnancy causes detrimental effects on embryo number and fetal development in mice. Scientific Reports. Nature

7. Zhou, Q., Song, L., Chen, J., et al. (2021). Association of Preconception Paternal Alcohol Consumption With Increased Fetal Birth Defect Risk. JAMA Pediatrics, 175(7):742-743.