Sex is war. Okay, that’s a contentious statement to grab your attention, and probably not the best lens to view all of human loving and procreation through, but the fertilization process in human sex does sometimes resemble a military operation.
The sperm-meets-the-egg part of reproduction is not the beginning. There is a complex saga leading-up to the moment of fertilization, one which takes thousands of sperm on a mission which none come back from. There are an array of sperm-types, such as: kamikaze sperm, warrior sperm, two-headed sperm. And they’re all in a Darwinian battle for survival.
MYTH: A normal sperm profile ensures fertility.
FACT: This is not true.
The vast majority of sperm cannot fertilize. Most sperm are produced with a genetic disadvantage that won’t even allow them to fertilize. The vast amount of sperm are there to die as fodder.
Scientists at Syracuse University (2013) have concluded that sperm do compete against each other within the vagina. This research echoes Robin Baker’s book Sperm Wars (1995), where he contests that sperm have evolved to “battle” against other men’s sperm en-route to the egg. Our pre-civilized tribal ancestors are likely to have been non-monogamous and promiscuous. Many currently existing tribal groups around the world show such relationships. An effect of sex with multiple partners in a short time-frame would be that a woman would have different men’s sperm inside her. One man’s sperm would be more likely to survive and fertilize if it could negatively influence another man’s sperm’s path toward the egg.
Competition may also affect sperm count, say the authors. When men spend more time away from their partners (time that their partners could have spent with other males), the number of sperm in their ejaculate increases upon their next copulation, according to Todd Shackelford and Aaron Getz at Florida Atlantic University.
Semen coagulates within seconds after ejaculation and then liquefies or decoagulates about 15–30 minutes later (Mandal and Bhattacharyya, 1985 Robert and Gagnon, 1999). Baker and Bellis speculate that this keeps the semen in place while sperm travel to the cervix, and at the same time prevents the passage of rival sperm from subsequent males.
Mandel and Bhattacharyya (1987) measured semen coagulation in humans, and found that if the male had not ejaculated in the previous two days liquefication times were significantly decreased. Thus, by implication, men who copulate frequently (which may include multi-partner matings) deposit semen that coagulates for longer periods of time.
Though many people today choose a path of monogamy, our evolutionary wiring looks to be built for a different way of sex and procreation.
In Human Sperm Competition, Baker and Bellis argue that the varying forms of sperm, known as polymorphism, “reflects a division of labour between the sperm in an ejaculate, each sperm having a different role to play in sperm warfare between males.”
Some sperm almost behave like a kamikaze. They are programmed for early death due to their DNA fragmentation. This is called apoptosis. These sperm can exhibit healthy, fertile behaviour, and then suddenly display cell-suicide.
The below image shows a simplified array of the forms sperm can take. The “abnomal” forms are actually very common. Remember, an ejaculate sample with 4% “normal” sperm is considered healthy.
So, how can this relate to you personally?
If you’re reading this, you’re most likely aware of semen analysis. If you haven’t had it done already, we recommend you or your partner get a semen analysis to see how much of a factor sperm health is in your infertility.
The major factors looked-at to measure semen health are:
- Sperm motility
- Sperm count
- Sperm morphology
Sperm motility translates to the layperson as the sperm’s ability to swim towards the egg. It is the sperm’s movement. High sperm motility means a relatively high number of sperm per ejaculate can swim in the right direction at a healthy speed. Motility is generally graded to the following criteria:
Grade 4: The sperm move in a fast and in a forward progression and in a straight direction.
Grade 3: The sperm move forward but in a curved direction and/or at a slower speed.
Grade 2: The sperm move slowly and their direction is hard to define.
Grade 1: Sperm move but do not move in a forward direction.
Grade 0: The sperm show no signs of movement.
Sperm count is the concentration of sperm per milliliter. According to the World Health Organization, Over 15 million sperm per milliliter is considered a normal sperm count (2010).
Sperm morphology is the shape of the sperm. “Normal” sperm actually refers to only a small fraction of sperm per ejaculate. Healthy morphology according to the World Health Organization (2010) is to have 4% per sample categorized as “normal sperm.”
Sperm morphology is a predictor of success for IVF treatment. In procedures with implanted sperm, a sample is selected based on its morphological characteristics.
The role of sperm in IVF treatment
An ICSI (Intra-cytoplasmic sperm injection) involves taking a motile, morphologically-normal sperm and injecting it into a viable egg (oocyte) under laboratory conditions. All it takes is one healthy sperm and one healthy egg. Specialists can test for some (but not all) genetic problems before you begin the ICSI procedure. The fertilized egg (embryo) is then transferred to the mother-to-be’s womb. This treatment is used in nearly half of all IVF treatment programs.
ICSI treatment is likely to be recommended if you (or your partner):
- have a very low sperm count.
- have a relatively high percentage of abnormally shaped sperm.
- produce sperm but cannot ejaculate them. It is possible for men who have undergone vasectomies to father a child through ICSI treatment. This may also be chosen if you or your partner has erectile problems which prevent fertilization.
A cycle of ICSI usually takes around four-to-six weeks to complete. ICSI has, on average, a higher success rate than other forms of IVF.
Male-factor infertility accounts for about 30% of couples’ infertility issues. If you haven’t yet had an analysis of you or your partner’s sperm, we recommend talking to your doctor about doing so.
You can read about how to increase sperm count, motility and general men’s fertility health in this Fertilitypedia article.
Modern science gives us the measurements we need to understand our chance of conception. An excellent starting point is to go to Fertilitypedia.com and click on the Chance to Conceive link. You can do this with or without test results from a semen analysis. This online test will take you through a health-related questionnaire which gives you the opportunity to input you and your partner’s vital information and generate an individual and coupled chance of conception. This information can be stored as you begin your own customized Personal Health Profile, and you do not have to sign up to do it.