Author – Phoebe Chan – BSc (Hons) Nutrition and Human Health
Fertility is a person’s ability to conceive children. In general, when a woman is unable to get pregnant after at least one year of unprotected sexual intercourse, she is considered to have infertility. However, infertility is not strictly a female problem, in 35% of couples who cannot conceive, the cause can be attributed to factors on both the female and male (1).
Factors Affecting Fertility
Lifestyle Behaviours/Factors
The new trend of modern lifestyle is that people delay starting a family due to educational and career pursuit, these individuals tend to be older and overweight (2). Women who have irregular periods and are overweight are less likely to ovulate each month than women with regular periods. Being overweight is also associated with an increased risk of miscarriage and of problems during pregnancy and delivery. Losing weight has been shown to improve fertility and increase the chance of getting pregnant. Men who are overweight may have suboptimal sperm and therefore reduced fertility (3).
On the other hand, many studies have looked at the effect of low body mass index (BMI) on reproductive ability. It has been shown that inadequate diets can disrupt the physiological reproductive function and greatly increase the risk of infertility (6). In men, being underweight is often associated with malnutrition and an unhealthy lifestyle, which can lead to hormonal imbalance and reduced semen quality (7). Women who are underweight, have been shown to take 4 times longer to get pregnant than women with a correct weight (8).
Some studies report drinking more than 5 units of alcohol a week may reduce female fertility (3). Apart from damaging other organs of the body such as the liver, heart and nervous system, it also affects reproductive health. Alcohol also depletes many essential nutrients from the body such as vitamin B, zinc, iron, magnesium, calcium, sodium and potassium, these vitamins and minerals are needed for most functions including reproduction (2).
Women who are smokers are 3 times more likely to experience a delay in getting pregnant than non-smokers, even though passive smoking. It reduces the ovarian reserve and damages the cilia inside the fallopian tubes. In men, smoking can reduce sperm quantity and quality (3).
Age
Female age is the most important factor affecting fertility. Women are born with all the eggs they will ever have and the number of eggs available decreases each day from birth onwards. In young women, the decline is fairly gradual but as women approach their mid to late 30’s, the decrease gets much steeper. In addition to the gradual loss of eggs, the quality also decreases with age. Consequently, women are less likely to become pregnant and are more likely to have a miscarriage. Male fertility also decreases with age, although at a much slower rate (3).
Nutritional Factors
In developing nations, nutritional problems such as deprivation, undernutrition and malnutrition are common, whereas eating disorders and obesity are common in developed countries.
In females, reproduction involves much greater energy expenditures than for males. In times during poor nutrition, like eating disorders or exercise induced amenorrhea, the ovaries stop working normally to protect the body. Both Bulimia Nervosa and Anorexia Nervosa suppress ovulation in severely affected women.
Some nutritional factors may affect male fertility. High fat diets inhibit reproduction by affecting the physical and molecular structure of not only the sperm cells but also the developing foetus and offsprings (4).
On the other hand, there are certain nutrients that can help boost fertility:
Folic Acid: a high intake of folic acid has been linked to a lower rate of infertility and miscarriage in females. It is also linked to a better environment for a developing egg. In males, low folate levels have been linked to lower sperm count and motility.
Vitamin B12: research shows that a higher intake of B12 is linked to a lower risk of ovulatory infertility. In males, vitamin B12 may help sperm quality.
Antioxidants: if there is a build-up of free radicals, it can lead to oxidative stress, causing damage to the cells. Antioxidants help prevent these free radicals from damaging the cells. Since sperm have been shown to be highly susceptible to oxidative damage, there has been a lot of interest in antioxidant supplements and sperm quality. Early research indicates they might improve sperm motility (5).
Medical Conditions
Polycystic ovary syndrome (PCOS) is a common hormonal condition that affects women of reproductive age. It can cause hormonal imbalances, irregular periods, excess androgen levels and cysts in the ovaries. Irregular periods can make it difficult to become pregnant, causing infertility. Symptoms include heavy, long, intermittent, unpredictable to absent periods, acne or oily skin, excessive hair on the face or body and weight gain. Unfortunately, there is no cure for PCOS, but symptoms can be improved (11).
There is an association between endometriosis and fertility, although it doesn’t necessarily mean endometriosis causes infertility. Due to the lack of research, the links between fertility and endometriosis are not fully known. In some cases, it may be because the disease distorts the reproductive organs. It is estimated that 60-70% of those with endometriosis can get pregnant spontaneously (12).
How to Boost Fertility
It is important to prepare the body and adjust lifestyles accordingly to maximise the chances of conception. Here are some tips which may make a difference to fertility:
- Avoid alcohol: it is a good idea to avoid or strictly limit alcohol as this reduces fertility. Department of Health advises to avoid alcohol completely if trying to conceive or during pregnancy.
- Exercise: women who exercise regularly are less likely to experience the uncomfortable side effects of pregnancy such as back pain, piles and swollen ankles. A fit, healthy body is also likely to cope better with child birth. Although, it is important to find a balance as excessive amounts of exercise can lead to fertility problems such as irregular periods and anovulatory cycles.
- Supplement: taking a supplement specially formulated for before conception such as one containing folic acid, l-arginine, vitamin D, CoQ10 and vitamin B12 can help support the nutritional requirements of women trying to receive. All women are advised to take a supplement containing 400 mcg of folic acid daily while trying to conceive and for the first 3 months of pregnancy (9).
Foods to Boost Fertility
Oily Fish: salmon, sardines and mackerel are rich in omega-3 fatty acids which reduce inflammation, balance hormones and improve blood flow to reproductive organs. Research has shown omega-3s enhance egg quality and encourage embryo development.
Leafy Greens: spinach and kale are great to enhance ovulation as they are good sources of folate, iron and vitamin c that may improve fertility.
Berries: blueberries, raspberries and strawberries are full of antioxidants that protect eggs and sperm from oxidative stress. Motility and sperm are improved by antioxidants such as vitamin C and polyphenols. They are also rich in fibre which is important for hormone and gut health.
Greek Yogurt: one of the best fertility-increasing foods is full-fat Greek yogurt since it is packed with probiotics, vitamin D and calcium. Vitamin D promotes ovarian activity and increases quality of sperm (10).
Frequently Asked Questions (FAQ’s)
What Is Fertility?
The natural ability to conceive a child. In both men and women, fertility depends on the proper functioning of the reproductive system.
What Are the Factors Affecting Fertility in Women?
Age, ovulation issues, hormonal imbalances and lifestyle choices
What Are the Factors Affecting Fertility in Men?
Sperm quality, lifestyle factors, infections and heat exposure
Does weight affect fertility?
Yes, both underweight and overweight individuals may experience hormonal imbalances that affect ovulation and sperm production.
References
- https://www.hopkinsmedicine.org/health/conditions-and-diseases/fertility-and-reproductive-health
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8812443/#bib24
- https://fertilitynetworkuk.org/learn-about-fertility/factors-affecting-fertility/
- https://pubmed.ncbi.nlm.nih.gov/25346452/
- https://thriva.co/hub/womens-health/how-does-diet-affect-fertility
- https://pubmed.ncbi.nlm.nih.gov/32397485/
- https://pubmed.ncbi.nlm.nih.gov/31393367/
- https://pubmed.ncbi.nlm.nih.gov/26875986/
- https://fertilitynetworkuk.org/learn-about-fertility/factors-affecting-fertility/lifestyle-fertility/conception-tips/
- https://ivflondon.co.uk/foods-for-fertility-nutrient-rich-options/
- https://www.who.int/news-room/fact-sheets/detail/polycystic-ovary-syndrome
- https://www.endometriosis-uk.org/endometriosis-fertility-and-pregnancy
