Fertility concerns are surprisingly common among couples, with research showing that about 1 in 7 couples has some difficulty conceiving, and about 12% of women between 15 and 44 seek relevant medical intervention.
It is good practice to see your doctor if you have not conceived after 1 year of trying, or sooner if you are above 36 years of age, or if you are aware that you may have fertility problems.
With regards to nutrition, we know that a significant portion of women of childbearing age in general, as well as women who struggle to conceive in particular, don't meet dietary recommendations for such important food groups as vegetables, cereal grain, as well as folate, iron and other needed micronutrients. At the same time, they are exceeding fat intake guidelines.
Adherence to dietary recommendations is positively affected by sociodemographic factors: mainly education, as well as non-smoking status, and evidence shows that changing certain lifestyle habits can improve fertility and pregnancy outcomes, and the newborn's later health.
As birth rates in the more developed countries are at their lowest measured points, such modifiable factors as diet, smoking, alcohol and stress are very relevant to public health research, to identify the ways to improving conception and pregnancy outcomes.
Let's see which are the science-backed changes that have been shown to benefit fertility.
NUTRITIONAL CHANGES
MACRONUTRIENTS
Avoid engaging in the latest trend of keto / intermittent fasting / high protein or fat / low carb diets.
These may only be 'potentially' useful tools in the hands of a dietitian, after assessing your individual health status, needs and goals.
Without specialist approval and guidance, these can be risky or not health-promoting to follow.
Following well-researched dietary guidelines of major relevant bodies such as the World Health Organization (WHO) or the US Dietetics Association (USDA), can help women reach the needed daily intake of dietary folate, iron, calcium, omega-3 fatty acids, as well as both men and women regulate cortisol and testosterone levels, and receive important micronutrients that we analyze below.
MICRONUTRIENTS
Supplementation of vitamins & minerals has a small but beneficial effect on fertility, through reducing oxidative stress and improving oocyte quality, maturation, fertilization and implantation. Some of the most important such micronutrients are noted next.
Antioxidants
Boosting antioxidant levels, through vitamins A, B2, B6, C, E and glutathione peroxidase (GSH-Px) can help strengthen the antioxidant defense system and reduce oxidative stress, with a potential benefit to fertility.
The effects of different antioxidants and their benefits to 'time-to-pregnancy' appear to relate to age and body mass index (BMI) :
In women of normal weight (BMI < 25), increasing Vitamin C appears to lead to shorter time to pregnancy (HR 1.09).
In overweight women (BMI ⩾25) β-carotene has a much more pronounced effect (HR 1.29)
In women aged <35 years, β-carotene and vitamin C have positive effects (HR 1.19 and 1.10)
In women aged ⩾35 years, Vitamin E has a positive though less pronounced positive effect (HR 1.07)
Folic acid (Vitamin B9)
Intake of 800 µg for at least 1 month before conception & through the first trimester of any fertility treatment (ICSI/IVF) is recommended.
Vitamin B9 has been associated with a greater chance of getting pregnant, and better embryo quality, by helping optimize the homocysteine pathway in follicular fluid.
Folic acid appears to be more beneficial to women with irregular (FR 1.35), short (FR1.36) or long (FR1.24) menstrual cycles, compared to a baseline of FR 1.15 for women with regular periods.
Vitamin D
Supplementation to reach and maintain optimal levels may improve menstrual frequency and symptoms for women with PCOS, and the chances of successful conception.
Due to reduced exposure to the sun, vitamin D is often a deficiency worth checking with your health care provider.
Multiple micronutrients (MMN)
(including antioxidants such as vitamins A, C, and E, folate, zinc, and copper)
Overall, there is a consistent, small and statistically significant benefit from micronutrient supplementation, in order to reach recommended daily intakes. It is worth consulting further with your doctor or health care provider.
The efficiency of providing multiple micronutrients (MMN) has been studied in subfertile women during a period of 4 weeks, preparing to undergo ovulation induction.
Nearly 70% of women receiving MMN supplementation were able to conceive successfully after 3 treatment cycles, compared to 40% of women that were only supplemented with folic acid.
In another study, women who had tried to conceive without success for 6 to 36 months, and received a MMN supplement, resulted in one-third of them becoming pregnant, compared with none in the group that received placebo.
These results were later validated in a double-blind RCT in similar, nutritionally adequate women.
FERTILITY IN MEN
There still is an important knowledge gap on the nutritional adequacy of men during preconception, despite having an important role in this phase. It is though understood that lifestyle factors have long-term, trans-generational effects, with obesity being linked with disturbed endocrinology, erectile dysfunction and higher sperm DNA fragmentation, while alcohol consumption reduces testosterone levels.
High protein diets appear to decrease testosterone, and increase the stress-related hormone cortisol by ~25%. These changes lower sexual drive and promote body fat gain.
Shifting to a balanced diet that provides the needed amount of high quality carbohydrates and protein can correct cortisol levels in ~10 days, while improving testosterone levels by about the same figure.
OTHER LIFESTYLE CHANGES
Healthy Weight
Safely reaching a BMI between 20 and 25 helps minimize problems in conceiving, with BMI higher than 30 being linked to lower fertility in both men and women.
BMI: Weight (kg) / [Height (m)] ^2
Alcohol
Alcohol is associated with multiple reproductive risks & negative effects on reproductive health. For women planning a pregnancy, avoiding alcohol completely is the safest option.
Men should also avoid or keep alcohol to a minimum, as it affects sperm quality, drinking no more than 14 units of alcohol / week and not exceeding 4.5 units in any single day -- which is ~ 2 cans of beer / 1 . 5 glass of wine.
Alcohol Units: Alcohol strength (ABV%) x volume (ml) ÷ 1,000
Smoking
Stopping smoking, and avoiding passive smoking, beyond improving your's and your partner's general health, will also have a positive effect on womens' fertility and mens' sperm quality.
Similarly, avoid meat-grilling smoke, which counts as 'dietary' secondhand smoking and also negatively affects birth outcomes.
Following research-backed recommendations over hearsay, and consulting with your doctor and dietitian for safe health recommendations is the best way towards this exciting life milestone.
As a last thing: don't forget to stay well hydrated as a way to keep multiple bodily functions performing optimally -- check my article on water & hydration
REFERENCES
Blumfield, M. L., Hure, A. J., Macdonald-Wicks, L., Smith, R., & Collins, C. E. (2012, June). Systematic Review and Meta-Analysis of Energy and Macronutrient Intakes During Pregnancy in Developed Countries. Retrieved from Nutrition Reviews Vol 70 Issue 6: https://pubmed.ncbi.nlm.nih.gov/22646126/
Caut, C., Leach, M., & Steel, A. (2019, December). Dietary guideline adherence during preconception and pregnancy: A systematic review. Retrieved from Wiley Online Library: Maternal & Child Nutrition / Vol 16, Issue 2: https://onlinelibrary.wiley.com/doi/full/10.1111/mcn.12916
Ghan, B. (2019, March). Systematic Literature Review of the Impact of Dietary Factors on Female Fertility. Retrieved from EC Nutrition: https://www.ecronicon.com/ecnu/pdf/ECNU-14-00609.pdf
Grajecki, D., Zyriax, B.-C., & Buhling, K. (2012, May). The Effect of Micronutrient Supplements on Female Fertility: A Systematic Review. Retrieved from Arch Gynecol Obstet: https://pubmed.ncbi.nlm.nih.gov/22302137/
Greger, M. (2013, February). Meat Fumes: Dietary Secondhand Smoke. Retrieved from NutritionFacts.org: https://nutritionfacts.org/video/meat-fumes-dietary-secondhand-smoke/
Greger, M. (2020, January). The Effects of Hormones in Milk on Infertility in Women. Retrieved from NutritionFacts.org: https://nutritionfacts.org/video/the-effects-of-hormones-in-milk-on-infertility-in-women/
Lan, L., Harrison, C., Misso, M., Hill, B., Teede, H., Mol, B., & Moran, L. (2017, September). Systematic review and meta-analysis of the impact of preconception lifestyle interventions on fertility, obstetric, fetal, anthropometric and metabolic outcomes in men and women. Retrieved from Human Reproduction, Volume 32, Issue 9: https://academic.oup.com/humrep/article/32/9/1925/3958121
Schaefer, E., & Nock, D. (2019, April). The Impact of Preconceptional Multiple-Micronutrient Supplementation on Female Fertility. Retrieved from SAGE Journals Clinical Medicine Insights: Women's Health: https://journals.sagepub.com/doi/full/10.1177/1179562X19843868#
United Kingdom National Health Service (NHS). (2020, June). Infertility. Retrieved from NHS: https://www.nhs.uk/conditions/infertility/
Van Heertum, K., & Rossi, B. (2017, July). Alcohol and fertility: how much is too much? Retrieved from Fertility Research and Practice Vol 3 Issue 10: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5504800/