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When’s the best time to have sex to get pregnant?The most effective time to have sex is during your fertile window, which can last up to six days every month. These six days are the five days leading up to, and the day of, ovulation (NICE 2013), when your body releases an egg.
Your egg will survive for about a day once released. But sperm can survive for up to a week inside you. So there is a six-day window for sperm to wait for and then meet an egg.
You are most likely to conceive if you have sex within a day or so of ovulation (NHS Choices 2015). However, it’s tricky to pinpoint the exact day or two just before ovulation. So if you don’t want your sex life to be ruled by the calendar, your best bet is simply to enjoy sex every two or three days.
If you want to be more precise, though, you will need to work out when you will ovulate. When you’ll ovulate in any given cycle depends on:
A menstrual cycle can be as short as 21 days or as long as 40 days (Mihm et al 2011, FPA 2014, NHS Choices 2014). The average cycle is about 28 days.
Regardless of how long or short your cycle normally is, ovulation usually occurs about 14 days before your next period starts (FPA 2014, NHS Choices 2016) .If you have a 28-day menstrual cycle, you’re likely to ovulate around the middle of your cycle. If you have a short cycle, you could ovulate within days of your period ending.
Many women have a cycle length that varies by more than seven days (Mihm et al 2011, FPA 2014). If your menstrual cycle is different from one month to the next, your fertile window may also vary by about a week between each period.
That’s why it’s best to have sex every two to three days throughout your cycle (NICE 2013). It’s more effective than focusing your efforts only on the days you think you’re about to ovulate. Also, sex every two to three days improves the quality of sperm compared to daily sex (NICE 2013).
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How do I know when I’m about to ovulate?You may be very aware of when you ovulate, or you may not notice any changes at all. If you’re thinking about getting pregnant, get in touch with your body and you may start recognising the signs that you are approaching ovulation. This can happen at around three weeks before you expect your next period. Try looking out for:
- Increased vaginal discharge that’s wetter, and like stretchy egg white. This is called fertile mucus (FPA 2014, NHS Choices 2016).
- Slight discomfort on one side of your belly (mittelschmerz) (White 2015).
- Feeling more sexy (Cantú et al 2014).
One of the simplest ways of working out your fertile days is to check your cervical mucus every day (FPA 2014, NHS Choices 2016). Changes to your mucus are one of the easiest things for you to spot.
To find out more about your fertile window, try our ovulation calculator. And read our article for helpful tips for spotting other signs of ovulation.
Do irregular periods make it harder to get pregnant?Irregular periods do not necessarily mean that you are less fertile than women with regular periods. However, if your periods are irregular or are more than 36 days apart, it is worth seeing your GP.
Sometimes, irregular cycles are caused by conditions such as polycystic ovarian syndrome (PCOS) or a thyroid disorder. These conditions could affect your chances of conceiving, so it is better to get help sooner rather than later (NICE 2013).
The more irregular your periods are, the more difficult it can be to work out when you’re fertile. So practise looking for changes in fertile mucus by checking daily (FPA 2014). Try to have sex when you notice two or more days of wet, slippery mucus. Or you may find it easier to just have regular sex throughout your cycle.
Some women use ovulation kits to pinpoint their most fertile time. Most of these kits test for the peak of luteinising hormone, or LH, which is the actual trigger for egg release. You could use these to find out when you are most fertile during your cycle, although using them to time sex won’t necessarily increase your chances of getting pregnant naturally (NICE 2013).
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Last reviewed: March 2017
ReferencesCantú SM, Simpson JA, Griskevicius V et al. 2014. Fertile and selectively flirty: women's behavior toward men changes across the ovulatory cycle. Psychol Sci 25(2): 431-8. [Accessed February 2017]
FPA. 2014. Bodyworks. Your guide to understanding reproduction. London: Family Planning Association. fpa.org.uk [Accessed February 2017]
Mihm M, Gangooly S, Muttukrishna S. 2011. The normal menstrual cycle in women. Anim Reprod Sci 124(3-4): 229-36. ncbi.nlm.nih.gov [Accessed February 2017]
NHS Choices. 2014. Periods and fertility in the menstrual cycle. Live Well. nhs.uk [Accessed February 2017]
NHS Choices. 2015. Getting pregnant Health A-Z. nhs.uk [Accessed March 2-17]
NHS Choices. 2016. How can I tell when I'm ovulating? Common Health Questions. nhs.uk [Accessed February 2017]
NICE. 2013 . Fertility: assessment and treatment for people with fertility problems. National Institute for Health and Care Excellence. Clinical Guideline 156. London: NICE. nice.org.uk [Accessed February 2017]
White CD. 2015. Mittelschmerz. medlineplus.gov [Accessed February 2017]