Understanding Fertility: When Can You Get Pregnant?

Getting pregnant is not as easy as everyone thinks. There is only a short window when the sperm can fertilise the egg.

Here we look at when you can and can’t get pregnant and how you can tell if you are at risk. We recommend getting yourself a period tracker app that can help tell you when you are probably ovulating, and we offer some advice on how to tell when you are ovulating – that is, when the egg can be fertilised by sperm.

When you (generally) won’t get pregnant

When you have your period (this is almost always true unless you have really short cycles, in which case near the end of your period, it is vaguely possible because you could ovulate really early)
The week before your period (this is almost always true because you have already ovulated, and the egg is gone)
From semen that has been in the open air for more than a few minutes (it dies)
From semen on toilet seats (see point above)
From giving someone a blow job (impossible, unless afterwards you scoop the semen into your vagina, and are ovulating at that time)
From having anal sex (unless some semen got in your vagina, which is unlikely because it would seem poor hygiene to do that)
From having someone go down on you (impossible unless they have a mouthful of fresh semen when they do it, and you are ovulating at that time)
From being fingered (unless someone has fresh semen or precum on their fingers, then fingers you, and you are ovulating at that time)
If you have sex with a condom (unless the condom broke, has a hole in it, or slipped off, and you are ovulating at that time)
If semen doesn’t get on your vulva or vagina
If you are on birth control that prevents ovulation
If you are on birth control that physically blocks sperm from entering the cervix (like a diaphragm, sponge or condom), and it was used properly
If you are postmenopausal and no longer ovulate
If you do not have functioning ovaries and do not ovulate
If you have been surgically sterilised
If you haven’t started ovulating yet
Sometimes if you have really irregular periods, it means you have irregular ovulation, and may find it much more difficult to get pregnant
If you are on hormone treatments to transition from female to male (because you don’t ovulate)

When you can get pregnant (naturally)

When you are ovulating, which is typically the halfway point between two periods, and fresh semen is on or in your vagina or sometimes even the vulva
A few days before you ovulate, and have sperm that stays alive for those days inside your vagina, uterus or fallopian tube

Fun facts about getting pregnant (or not)

A viable egg only stays that way for about 12 hours as it travels from the ovary to the uterus
The sperm actually fertilises the egg in the fallopian tube, so if the egg makes it to the uterus unfertilised, it’s useless
Once the egg is fertilised in the fallopian tube, to actually get pregnant the egg must implant on the side of the uterus wall, which takes a few days
There are so many things that can go wrong when trying to get pregnant! It’s actually pretty hard