When you’re planning to start a family, it’s helpful to get to know your reproductive cycle. Recording your menstrual cycle helps to determine when you’re most fertile and helps increase your chance of conceiving.

Body Changes

Every month, one of your ovaries produces a mature egg. Around the same time, your uterus prepares for fertilisation and your cervical mucus thins to allow sperm through more easily. Once the egg is released, you have ovulated.

An egg can be fertilised up to  24 hours after ovulation

The egg can be fertilised up to 24 hours after ovulation, as it makes its way along the fallopian tube to the uterus. If it’s been successfully fertilised by a sperm, it will then implant into your uterus lining and start to develop into a baby.

Understanding your fertile window

Your most fertile time, and the best time to have sex in order to increase your chances of conceiving, are the few days leading up to and including ovulation.

If you wait until you have ovulated to have sex, the sperm may not reach the egg in time for fertilisation to take place. Sperm, on the other hand, can survive for several days inside your body waiting for the egg to be released.

Happy couple online

Having sex during your most fertile phase may help increase your chances of conception

How to determine when you ovulate

Every woman’s cycle is different, so we have created this simple ovulation calculator to help you determine your own ovulation date. To use it, you’ll need to know the first day of your last period and the typical length of your menstrual cycle (if it’s irregular, keep a record over a few months and work out the average).

Once you know when you’re likely to ovulate, you can plan the best time to have sex to conceive.

Other signs to determine your fertile window include:

  • Changes in cervical mucus: The cervix is the lower, narrow part of your uterus, which opens into the vagina. Mucus produced by the cervix changes during your menstrual cycle due to hormones, and can help predict your fertility.

    Before ovulation (just after your period): You’ll produce very little mucus just after your period, if at all. It will be thick, sticky and white or opaque in colour and your vagina will feel quite dry. As sperm require mucus to help meet the egg, there is little chance of getting pregnant at this stage.

    Approaching ovulation: Mucus production will increase and become creamy white or cream in colour and your vagina will feel moist. You have a better chance of getting pregnant at this time.

    Around ovulation: Your mucus will be thin, clear and very stretchy (like raw egg white) and your vagina will feel quite wet. You have the highest chance of getting pregnant at this time.

    After ovulation: Your mucus will become thick and sticky again and your vagina will start to feel quite dry. Your chance of conception during this stage will start to decline.
  • Higher basal body temperature: Your basal body temperature is your resting body temperature. Recording this temperature over a few months can help you more accurately predict when you ovulate. Ovulation usually happens at the beginning of a temperature rise that’s sustained for at least 3 days. Factors like heating, travel, time of day, diet, work hours and amount of sleep can affect your temperature. 

    To help record your accurate temperature, it’s best to take your temperature at the same time every morning, before getting out of bed, with a fertility or digital thermometer. 
  • Abdominal pain: Try and pay attention to any pain you might feel in your belly, as this could be a sign of ovulation.
  • Premenstrual symptoms: You may also get typical PMS symptoms like sore breasts, bloating or moodiness when you ovulate.

Enjoy this special time together

Keep your babymaking fun!

Couple planning for pre-pregnancy

Deciding to have a baby is an exciting and loving time. Don’t let having sex to a schedule take away from the fun. Relax and enjoy your intimate moments together.

Common conception questions 

  • Does age affect fertility? Yes, the quality of your eggs and ovulation patterns are affected by your age. Women are most fertile from their 20s to their early 30s. Age can also affect a man’s sperm quality and quantity.
  • How long will it take me to conceive? Half of all couples will get pregnant within 2-3 months of trying and 85% will get pregnant within 1 year1. However, it's important to realise that every couple is different. The best thing is to relax and take it easy as stress is not beneficial for couples trying for pregnancy.
  • What can I do if it’s not happening for us? If you’re doing all the right things, but you’re still not pregnant after 6 months of trying, ask your doctor for advice. Furthermore Fertility NZ has more information on its website, click here to view.

More tips on planning for a baby

Now you know the best time to have sex for a baby, take a look at our pre-conception nutrition and lifestyle pages. They contain lots of useful information about preparing for a healthy pregnancy before you start trying for a baby.