Conception: the basics

Dr Andrew Murray from Fertility Associates lays out tactics for a good-quality and successful conception (it’s a bloke thing). 

To make a baby you need three ingredients: eggs, sperm and the ability to get them together. This is true for any type of conception, be it natural or with fertility treatment. So to maximise your chances of conceiving naturally we need to understand how to bring these three things together optimally.

The target
Ovulation is the process where an egg is released from the ovaries. It generally occurs 14 days before the next period. If your periods are reasonably regular, say every 26 to 30 days, then there is a good chance you are ovulating regularly. However if your periods are irregular or five weeks or more go by between periods, then you should see your doctor.

When ovulation does occur it can be associated with certain symptoms including mild mid-cycle pain, increased watery/stretchy mucus and after ovulation the body temperature goes up about one degree. Home ovulation kits pick up a surge in the luteinising hormone (LH) that peaks about 36 hours before ovulation occurs.

When the egg is released it is swept up by the fallopian tubes and survives for about 12 to 24 hours. If a sperm doesn’t find the egg in this time, it dies and is destroyed by the immune system.

By the way, the most eggs a woman ever has is before she is born. About half-way through her time in the womb she will have seven million eggs, but from there it’s all down hill. By birth she will have one million eggs, by puberty 300,000, and by her mid-thirties maybe only 25,000 left. It still sounds like a lot, but the other issue is that you tend to ovulate your best eggs when you are younger. This explains why miscarriages and fertility problems become more common as you get older.

The assault weapon
The sperm have a different journey. Unlike eggs that live for just 12 to 24 hours, sperm can survive for two to three days in the female body so they have a bit longer to get the job done. A normal sperm count is between 20 and 250 million sperm per millilitre. Why millions of sperm for just one egg? Remember, they have only 24 hours max to find the egg, and it is very much like an SAS assault course to get there. To start with, the vagina is acid and sperm like alkali.

The cervical mucus has white blood cells (like bouncers at a nightclub) taking out the sperm and only allowing a select few in. For the lucky few hundred sperm that make it into the uterus, further white cells take out some more, until a few sperm eventually find their target. Many will try to attach to the egg but in general only one penetrates the egg shell and fertilisation occurs.

A lot of the couples I speak to fall into the trap of approaching baby-making as if it’s a “surgical strike”, targeting ovulation like a stealth bomber and timing intercourse accordingly. The thing is, we are dealing with a biological system and a woman’s body is not a Swiss watch where everything happens at exactly the same time each month. By trying to be so accurate you risk turning the whole process, which should be fun, into a science experiment.

My advice is to go from being a stealth bomber to a carpet bomber. Okay, there is only one egg per month, but there are millions of sperm available and they have up to three days to complete their mission. Some research also shows you get better quality sperm from more frequent ejaculations. You don’t have to save up for one big “invasion”.

Have regular intercourse from about day 10 to 18 and you will have all the bases covered. It doesn’t have to be every day, every other day is fine.


Dr Andrew Murray is Medical Director of Fertility Associates Wellington and a New Zealand Committee Member of the Royal Australia and New Zealand College of Obstetricians and Gynaecologists (RANZCOG). He is also a Senior Lecturer at Wellington School of Medicine, University of Otago and one of the consultants at Wellington Hospital.




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