Sperm meets egg…and then what? Everything you didn’t know about conceiving

The method of baby-making might sound simple enough. From the egg’s release, to the speeding sperm, to fertilisation and implantation, the journey to conception is a wonder. Here’s the lowdown on exactly what happens behind the scenes when it comes to making a brand new human being.

Ready, set, go!

During sex, the sperm are ejaculated from the penis – around 250 million per ejaculation to be precise! If no condom is used, these speed-demons are free to swim their way up the vagina. The first challenge is to make it through the cervix (and mucous) into the uterus. From here they’re on a mission to reach the fallopian tube, searching for an egg to fertilise.

Only the strongest survive

It only takes a few hours or less for the sperm to make their way into the fallopian tube. Many will die along the way, but these tough little guys can survive for 8 hours in the vagina and 3-5 days in the uterus and fallopian tubes (which is why a woman should take the morning after pill ASAP if an accident such as a torn condom has occurred). Only about 200 sperm will make it to the egg.

The egg must be ready

Menstruation (periods) must have started for fertilisation to occur. However, there is a slim chance pregnancy can occur if there has been unprotected sex in the month the periods start and an egg was released. But it’s always best to wait until you’re with a partner you trust anyway. Thousands of ova (eggs) are carried inside the ovaries and once a month, released mid-menstrual cycle (approximately 2 weeks before the period). This is the golden ticket a sperm is looking to claim.

There’s only one winner

Once a sperm unites with an egg, fertilisation can occur and no other sperm can get in. It’s a bit like the winner holding up a sign saying ‘Too late, it’s all mine!’ to the rest.

Divide and conquer

Once the egg is fertilised, it immediately splits into two cells. These then divide again and again over the course of a few days, as the ever-growing cluster of new cells finds its way to the uterus. This compact cluster of cells is known as a blastocyst.

Time for a new home

Once this cell cluster is snuggled comfortably in the lining of the uterus after 6-10 days, it keeps on dividing over and over, making billions more new cells. It’s more than a fertilised egg at this point, and the sex is already determined. Even so, at this point, after what seems like a long and incredible journey, the female is officially ‘pregnant’.

Let the cooking commence

All being well, a baby will be born after about nine months, ‘cooking’ in its comfy little sack until it’s ready. That’s usually enough time for the baby’s parents to prepare!

Remember, if you and your partner are not trying to conceive, having sex without contraception and a condom is never recommended, because you may not only end up with an unwanted pregnancy, but also an STI.


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