Whether you’re trying to conceive or you’re not ready for a baby, here’s everything you need to know about your fertility window.
Medically reviewed by Dr Juliet McGrattan (MBChB) and words by Rhalou Allerhand
If you’re trying to conceive or trying to avoid getting pregnant, either way you probably have lots of questions about when you are most fertile: how often do you need to have unprotected sex to get pregnant? Can you get pregnant on your period? And, when should you have sex, exactly? (Or not have unprotected sex, if you’re not interested in having a baby right now?)
We answer your most common fertility questions to help you make an informed decision about birth control.
Can you get pregnant on your period?
Whether you’re trying to conceive or you’re looking for ways to avoid pregnancy, you should know that the chances of getting pregnant on your period are actually extremely low.
‘If you have regular cycles, then it’s highly unlikely you can get pregnant on or two days before your period as, after ovulation, the egg is only around for 12-24 hours and ovulation in a regular cycle will have occurred two weeks before your period,’ says Fertility and pregnancy expert Zita West.
‘It is still very unlikely for this to happen even with irregular cycles, but it is important to understand the fertility cycles, to look out for your fertile time,’ she adds.
Your fertile window
The truth is, your fertile window each month is actually pretty small—about eight to nine days total. To conceive, a man’s sperm must fertilise a woman’s egg within 24 hours of ovulation (when a woman’s ovary releases an egg).
In a typical woman whose menstrual cycle is 28 days (with day 1 the first day of her period), ovulation typically occurs between days 11 and 21.
When is the best time to conceive?
A man’s sperm can live in the woman’s reproductive tract for up to 7 days. Some research shows the best time to have sex to conceive is actually two to three days before ovulation. Your chances of getting pregnant actually drop pretty sharply after ovulation.
The truth is, your fertile window each month is actually pretty small – about eight to nine days total.
That said, there’s a tiny chance you could get pregnant two days before your period. There is also a risk you could become pregnant during your period too. There’s no absolute ‘safe’ time although there are certainly times when your risk of conceiving is higher.
If you have irregular menstrual cycles, then it becomes difficult to predict when ovulation may occur and there’s a chance you could ovulate earlier than you would expect during a regular cycle.
How often should you have sex to get pregnant?
If you are wanting to become pregnant, then it’s advisable to have sex every two to three days throughout your cycle. It’s not necessary to track your cycle and pinpoint when you are going to ovulate, for some couples this may even cause stress. Because sperm can live for seven days, regular sex every few days will mean there are sperm ready and waiting in the fallopian tubes to fertilise an egg when ovulation does occur.
What is natural family planning?
Natural family planning is a method which allows women to look out for and track changes in their body so they can time their intercourse to avoid or maximise their fertile time, according to whether or not they are wanting to become pregnant.
Looking at changes such as body temperature, cervical mucous secretions and the dates of their menstrual cycle, women can learn to predict their ovulation and time their sex accordingly. It requires commitment, is best taught by an expert and is often used in conjunction with fertility monitoring devices which check hormone levels in urine.
If you’re not interested in having a baby, it’s always best to speak to your nurse, GP or local family planning clinic for advice, and read our tips on choosing the best method of contraception for you.