In this session, Dr Adolfo de Prados, Gynaecologist at PreGen (UR Vistahermosa), Valencia, Spain has been talking about lifestyle factors such as diet, exercise, but also age, stress, alcohol, smoking that have an impact on your fertility.
Lifestyle factors infertility has become a huge problem that affects around 20% of the world’s population. Lifestyle factors can be modified to enhance overall well-being.
First, one of the most important factors is the woman’s and men’s age. This factor can affect fertility due to the pursuit of education, many couples are choosing to delay childbearing. Still, it’s important to remember that fertility decreases over time in both men and women. At the age of 40, men can have more DNA damage in their sperm, as well as a decline in the motility and viability of the spermatozoa. The reproductive timeline for women is more complex than for men. It’s because a woman is born with all the oocytes she will ever have, she’s not going to produce any oocytes later on. When she’s born, she has more or less 1-2 million oocytes and from then on, only 400-500 are going to be ovulated. Increasing age increases a woman’s time to pregnancy, and the number of oocytes starts to decrease after the age of 35-39. The odds of becoming pregnant and maintaining a pregnancy are connected to numerous factors. One of them is aneuploidy. Euploidy is inversely correlated with female age. The rates of euploidy decreased by 50% for women under 35, it decreases by 40% for women between the ages of 35 and 40, and 33% for women over 40. The possibility of finding a euploid oocyte after 44 is less than 3%. It’s impossible to change your age, but it’s still possible to change and focus your efforts on lifestyle factors.
The first thing you can do is change the way you eat. It may be a key part of maintaining good overall health, however, there are certain vitamins and food groups that could have a greater impact on reproductive health. In males, consuming a diet rich in carbohydrates, fibre, folate, and lycopene, as well as fruit and vegetables, correlate with improved semen quality. Consuming lower amounts of both proteins and fats is more beneficial for fertility. Another potential benefit could be the use of antioxidants, which play a pivotal role in the body by scavenging reactive oxygen species (ROS), if there are more ROS than the local antioxidants can remove, it results in oxidative stress, which leads to sperm dysfunction including sperm motility, altering DNA and decreasing their membrane integrity. Some vitamins like vitamin C, vitamin E, selenium and Coenzyme Q10 have a significant effect on semen quality. The Cochrane review, including 34 studies determined that men who use these oral antioxidants had a significant increase in live birth rates.
A woman’s diet might affect her fertility as well, particularly ovulation. Replacing carbohydrates with animal protein was demonstrated to be detrimental to ovulatory fertility. Adding just one serving of meat was correlated with a 32% higher chance of developing ovulatory infertility, particularly, if it was chicken or turkey. However, if we replace carbohydrates with vegetable proteins, it is demonstrated that it has a protective effect.
When it comes to fats, choosing trans fats in the diet instead of monounsaturated fats has been demonstrated to increase the risk of ovulatory infertility, consuming trans fat instead of carbohydrates correlated with a 73% increase in the risk of ovulatory disorder, but the use of multivitamins and different supplements have a positive effect on fertility. Women who take multivitamins may be less likely to experience ovulatory infertility. Some authors have posted the existence of a ‘fertility diet’. They emphasize that a higher monounsaturated trans fat ratio, the consumption of vegetables over animal proteins, a high-fat over the low-fat diary, a decreased glycaemic load, and an increased intake of iron and multivitamins can increase the chances of pregnancy.
It’s also important to look at weight and Body Mass Index (BMI), if it is below 18.5, it’s considered underweight, between 18.5 and 24.9 is normal, above 25 is overweight, and over 30 is considered obese. Body weight can have significant effects on health, including cardiovascular disease, diabetes, and infertility. Nowadays, there is an obesity pandemic, and this is a serious issue, particularly in industrialized nations. Obese men are 3 times more likely to exhibit a reduction in semen quality than men of normal weight. Several studies have demonstrated that an increase in BMI is correlated with a decrease in sperm concentration and decreased motility and an increase in DNA damage in the sperm. In addition, there is a relationship between obesity and erectile dysfunction.
Obese women had a higher rate of recurrent early miscarriage compared to non-obese women. There is evidence that these miscarriages in obese women may not necessarily be due to genetic alteration. There is no difference in egg quality rates between obese and non-obese women, suggesting that miscarriage may be due to other influences such as endometrial receptiveness. Obese women have higher rates of ovulatory disorder, so they are going to have a longer time to pregnancy than non-obese women. A positive aspect is that the negative effects of obesity may be reversible. It is often said that ‘we are what we eat’, but what we do in this context of obesity is not the only way in which weight can impact fertility.
Underweight men are also at risk of infertility, they tend to have lower sperm concentration than those who are at a normal BMI. Women wearing underwear and having extremely low body fat are associated with ovarian dysfunction and infertility. Additionally, the risk of ovulatory infertility increases in women with a BMI below 17.
Exercising is, therefore, as important as nutrition. A healthy amount of exercise can be beneficial for men and women who are looking for a pregnancy. Active men who exercise at least 3 times a week for 1-hour score higher in almost all sperm parameters compared to men who have a sedentary lifestyle. Nevertheless, bicycling more than 5 hours per week has been demonstrated to have a negative correlation with total motile sperm counts and sperm concentration. Excessive exercise can negatively alter energy balance in the body and affect the reproductive system.
In women, negative energy balance leads to menstrual abnormalities. Increased frequency, intensity, and duration of exercise were found to be significantly correlated with decreased fertility in women. There was a study that examined more than 2 000 women undergoing IVF, it was found that women who engage in cardiovascular exercise for 4 hours or more per week had a 40% decrease in the live birth rate.
A psychological review is also very important. Stress is a prominent part of any society, whether it’s physical, social, or psychological, and infertility itself is stressful due to the societal pressure, testing, diagnosis, treatment failures and even the cost with which infertility is associated. In a study that included nearly 1 000 men with conductive stress such as job, life events or even social strain were seen to have a significant impact on sperm density, total sperms count, mobility and morphology. It seems that certain parameters may potentially be linked to stress. Although there appears to be a relationship between stress and infertility, it’s uncertain which is the cause and which is the effect.
Psychological stress, such as anxiety disorder or depression, affects 30% of women who attend infertility clinics, possibly before infertility diagnosis and treatments. Receiving instruction on how to deal effectively or merely receiving support made a significant difference for women undergoing fertility treatment. There was a higher pregnancy rate in women who were part of a cognitive behavioural interventional group or simply a support group than those not receiving an intervention. Women who receive support and counselling may reduce their anxiety and depression levels, and this can increase their chances of becoming pregnant. Positive moods are correlated with an increased chance of delivering a baby, while higher levels of anxiety increased the chances of stillbirth, and fertilization of oocytes is also decreased when stress is increased. A possible explanation may lie in stress hormone levels. Therefore, psychological support has to be part of the multidisciplinary approach to infertility treatments.
It’s well documented that cigarette smoke contains over 4 000 chemicals and is associated with several health complications, such as cardiovascular disease, and it’s a clearly established link to infertility. Men who have smoked before or during attempts to conceive have a higher risk of infertility in comparison to non-smokers. Men who smoke tend to have a decrease in total sperm count, density, motility, normal morphology and semen volume. Smoking can reduce the mitochondrial activity in spermatozoa and can lead to a decrease in their fertilization capacity, and it can impact DNA integrity, leading to an increased risk of miscarriage.
Women who smoke seem to have similar effects on the reduction of fertility, it leads to a decrease in ovarian function and reduced ovarian reserve, but the uterine tubes and uterus may also be targeted by cigarette smoke, chemicals in cigarettes may impair oocyte pickup and the transport of embryo within the fallopian tubes leading to an increased incidence of ectopic pregnancy. It all leads to a longer time for conception and overall infertility.
Many studies have been conducted on the effects of alcohol and aspects of health including fertility. Some studies demonstrate the link between alcohol and infertility, however, it’s not entirely clear what amount relates to an increased risk. Some authors say that it should be limited to a total of 8 units of alcohol per week (1 unit equals 20 millilitres of alcohol). In men, alcohol has been linked with many effects, such as testicle atrophy, decreased live birth rate, decreased sperm count, sperm morphology and motility.
The positive aspect is that it can be reversible. The effects of alcohol on men and women are independent of the type of alcohol. No alcohol would be better than the other, beer is not better than vodka, for example, and this effect depends on the amount of alcohol. Women who experienced hangovers were more likely to be infertile suggesting and supporting that the amount of alcohol we consume matters. Alcohol can have different effects on women increasing the time to pregnancy, decreasing the probability of pregnancy rate by over 50% and decreasing the implantation rate. Alcohol can cause luteal phase dysfunction and abnormal embryo development. Women with high consumption of alcohol have a higher risk of miscarriage and fetal death.
Caffeine has become an integral part of society’s consumption, varying from 50 milligrams in a bottle of Pepsi, for example, to 330 milligrams in a big cup of coffee. However, caffeine has been reported to have negative effects on fertility. It has been associated with an increased time to pregnancy of over 10 months, particularly if the amount of caffeine is over 500 milligrams per day. The negative effects of caffeine during the first trimester are related to miscarriages, spontaneous abortion, and stillbirth. According to recent research, women who miscarried or had a stillbirth had an average of 145 milligrams of caffeine per day, and women who had live births consumed an average of 150 milligrams per day, indicating that there may be a narrow window for caffeine to impact fertility.
In men, the published evidence suggests that caffeine intake may negatively affect their reproductive function, possibly through sperm DNA damage. However, evidence of the effects of caffeine on certain parameters is inconsistent and inconclusive.
Another thing worth mentioning is illegal drugs which also have a negative impact on fertility. Studies of the effects of illegal drugs on human fertility have been scarce due to ethical considerations. Marijuana is one of the most commonly used drugs around the world, both centrally and peripherally, and causes abnormal reproductive function. In males,
marijuana has been reported to decrease spermatogenesis, sperm motility, and sperm capacitation. Women who use marijuana are at an increased risk of primary infertility due to a hormonal disbalance and a negative impact movement through the oviducts and placental and fetal development and may even cause stillbirth.
Another commonly used drug is cocaine, which is a stimulant for both the peripheral and central nervous system and causes vasoconstriction and anaesthetic effects. Long-term users of cocaine claim that it can decrease sexual stimulation. Men can find it harder to achieve and maintain an erection and to ejaculate. It has been demonstrated that cocaine affects spermatogenesis, but less is known about cocaine’s effects on women. It may cause impaired ovarian responsiveness to gonadotropins and placental abruption.
The last group of illegal drugs are the opioids, such as heroin and methadone. In men who take heroin sexual function become abnormal. Even after cessation, sperm parameters, specifically the motility of the spermatozoa, also decrease with the use of heroin and methadone. In women, placental abruption may also be a cause of infertility.
Other things can also affect your fertility. It’s, for example, exposure to different kinds and amounts of radiation. This can have lasting effects on human reproduction. The convenience of the cell phone has dramatically increased its usage in the last decade. This has negative effects on the radiofrequency electromagnetic waves used by cell phones on infertility. Cell phone usage has been linked with decreases in progressive motility counts and viability, and it’s related to an increase in ROS and an increase in abnormal sperm morphology. One study that evaluated 52 men demonstrated that men who carried a cell phone around the bell line were more likely to have decreased sperm motility compared to men who carried their cell phone elsewhere.
In women, there is no scientific evidence related to the effect of the use of mobile phones because the ovaries are inside their bodies while the testicles are outside.
Lifestyle factors and other behaviours are modifiable and may impact fertility. The evidence suggests that age may play an important role in determining fertility. Attempting pregnancy before the age of 35 for women and before 40 for men may provide the highest chance of success. Proper nutrition and having a normal weight, and exercising may impact fertility. Avoiding smoking and alcohol is crucial. Even though there are associations between psychological effects and infertility, it is hard to establish a cause-effect relationship. By understanding the impact of lifestyle on reproductive health, men and women are capable of controlling their own fertility potential.