The science of conception and infertility
What happens during conception?
It's all happening! A healthy, well-nourished egg is released from the ovary, and is caught by the waving arms of the tiny filaments around the end of the fallopian tube. This tube is about as wide as a hairbrush bristle, and about 10cm long. The egg itself is even smaller than the dot at the end of this exclamation mark! Isn't that amazing, but to the sperm, the egg is a giant. Twenty five million sperm could fit on this full stop.
As far as sperm is concerned, we talk in millions. Normal sperm counts range from 30 to 60 million per milliliter of seminal fluid, which will result in a healthy male depositing 280 to 400 million sperm in the vagina during one ejaculation. This might seem like an enormous number when just one is needed to fertilize the egg, but sperm face many hazards on their journey.
They move along by lashing their tails, and are encouraged to do this by a substance found in the female reproductive tract. It takes them about an hour of vigorous tail-lashing to complete the 18 cm marathon trip from the neck of the uterus, known as the cervix, to the place in the Fallopian tubes where, hopefully, the egg is waiting.
While the egg is waiting, part of the fluid that surrounds it sends out "love messages" to the sperm, alerting them to its presence and triggering their swim in the right direction. Perhaps these messages are selective, attracting the highly motile and vigorous sperm, rather than the very young or very old, which might be less viable.
On this journey, many of the sperm will be immobilized by the acidity in the vagina before they reach the relative safety of the alkaline cervix. Many get lost in the uterus, simply hanging around till they die, never finding the Fallopian tube in which the egg is waiting.
An egg is normally released by one of the two ovaries in each cycle, usually alternately. Sperm might pick the wrong tube entrance. What starts off like a crowd at a fun-run thins out quite rapidly.
The egg will wait for a great looking sperm for between 12 to 24 hours, but after that, it passes on. The sperm live longer, up to 3 to 5 days. Although they take 10 to 11 weeks to be produced, once released into the vaginal tract, 5 days is the most they can survive.
Before that lucky sperm can penetrate an egg, it undergoes a process whereby hormonal secretions in the female cause the release of two enzymes from the sperm, making the way clear for the final breakthrough by enabling the sperm to burrow through the egg's two outer coatings.
The fertilized egg is then wafted down the rest of the tube, helped along by the tube's rhythmic contractions, and by the hair-like projections that line it. This trip takes about a week, after which the egg reaches the uterus, and implants in the endometrium.
How can we help fertization happen?
- We need to know when ovulation has taken place
- It's better to have sperm waiting for the egg than the other way round
- Sperm and eggs must be "young" and strong
- Frequent intercourse is needed during the peak fertile time
The causes of infertility in men and women
Making a baby really does sound simple. A couple of ingredients from each partner, the correct "cooking time" and a bouncing bundle of joy should be yours about 40 weeks later.
The causes of infertility in men and women are well known.
- hormonal disturbances
- auto-immune diseases
- a toxic lifestyle
- poor diet
- a person's unique genetic tendencies.
How can nutrients increase conception?
It sounds a rather trite question, but how many prospective parents lack the essential phytonutrients and minerals that are important for optimum fertility? Less than half of Australian men and women aged between 19 and 44 don't consume the recommended servings of fruits and vegetables (excluding potatoes). Mineral deficiencies are common, with average intakes of selenium, calcium, iodine and magnesium often below the recommended daily intakes.
The most specific nutrients which have been shown to have a positive impact on foetal programming are the methyl donors. These nutrients are folic acid, vitamin B12 and methionine. Additionally, vitamin D plays a role in foetal health. The importance of a maternal supplement is obvious.
What can men do to help fertilization?
Men, on the other hand require more consideration. After all, they are blokes! Men are half the baby, but rarely get attention, both clinically and in published studies.
Basically, not all sperm are created equal. Of that 20 million per ml we mentioned, only about 50 per cent are motile, with 25% rapidly progressive. Sperm DNA damage is increased by lifestyle factors including inadequate nutrition, increased weight, smoking and substance abuse, as well as excessive coffee and alcohol intake. And other nutritional factors impinge on sperm health too. For example, vitamin D affects calcium levels in sperm.
Some exciting news for men is that daily sex reduces sperm DNA damage. So, frequent ejaculation is another way of reducing the exposure to sperm to oxidative damage in the testicular ducts.
Use your health professionals to get the best advice about what's safe. Many over-the-counter products need to be carefully scrutinized. For example, taking non-steroidal anti-inflammatories like ibuprofen, in mid-cycle, reduces rates of conception.
Fertility and conception
In summary, it takes two to tango. Fertility is a couple issue, not just a woman's issue. Good reproductive outcomes require a focus on both partners.