It takes two to tango
It's time to turn the spotlight to sperm.
A large meta-analysis study found that between 1981 and 2013, sperm count decreased by over half in some western populations. This is a worrying statistic in itself, but it is even more concerning to learn that the rate at which sperm count is decreasing is getting faster - sperm health is worsening more year on year.
For many years fertility has been thought of primarily as a female problem. But recent studies have shown that in couples struggling to conceive, male infertility contributed to 50% of cases. Of this 50%, around 2 in 5 were due to male infertility alone, and the rest were a combination of female and male factors. The studies mentioned above were based on total sperm count and sperm concentration. The decline shows that there are lesser numbers of sperm within semen samples. Furthermore, other studies have shown increases abnormal shape sperm and decreases motility. It has long been agreed that better semen quality increases the likelihood of pregnancy, though there is controversial evidence about the importance of different factors, including motility, shape (morphology) and semen volume.
But what is going wrong?
Despite the mounting evidence that sperm health is deteriorating, there is little causal evidence as to why this may be. Contributing factors to sperm deterioration are thought to be obesity, poor diet quality and exposure to environmental toxins; is it a coincidence that male factor infertility has increased at an alarming rate at a time that coincides with increasing prevalence of obesity, increasing exposure to radiation and environmental chemicals?
Several studies have shown that high male partner BMI has been linked to reduced fertility, mostly assessed by increased time to conception. High paternal BMI also has had association with less blastocyst development and less live births. This may be partly because body fat (known as adipose tissue) can produce a chemical called aromatase which converts testosterone into a form of oestrogen. Oestrogen is a sex hormone which is present in both women and men, but it has been found that if the testosterone to oestrogen ratio in males is incorrect, it can be linked to reduced sexual function and erectile dysfunction. Obesity is also a culprit for low testosterone: one study even found that weight increase from a healthy weight to obese had a similar impact on testosterone to aging 10 years! Given that testosterone is key in maintaining libido and sexual function in males, it is clear to see how increased body weight and subsequent decreased testosterone will impact fertility. These studies highlight the importance of paternal healthy weight.
Body composition
Body fat percentage is an important consideration when aiming to improve fertility, or when considering trying to conceive. BMI is a frequently used tool in healthcare and research, however is not always an accurate measure of body fat and weight, as it does not account for the difference in muscle and fat. Muscle is very dense tissue and therefore weighs a lot compared to fat, so a very fit muscular person of average height may have an ‘overweight’ BMI despite being in peak physical condition. A way around this is to monitor your waist circumference or hop on a body fat scanner at your local gym or leisure centre.
If you are overweight or feel that you might benefit from losing weight, there are some simple principles to follow:
Regular meals - it is important not to starve, and having regular meals and nutritious snacks can help make sure you don’t overeat at other times.
Increase your fruit and veg - think about your fruit and veg taking up half of your dinner plate, a quarter should be your protein source, and another quarter should be a carbohydrate source.
Focus on protein - make sure you are getting enough protein throughout the day to keep you satisfied and well nourished.
It can be tricky to navigate weight loss advice and stay on top of healthy eating. If you feel like you would benefit from more support or tailored guidance, contact us or talk to your GP.
References -
DOI: 10.1093/humupd/dmac035
DOI: 10.1111/andr.13396
DOI: 10.1177/0960327117703690
DOI: 10.1016/S0140-6736(97)10514-1
DOI: 10.1097/MOU.0000000000000745
DOI: 10.1016/j.mehy.2007.05.020
doi: 10.4103/1008-682X.122365