Pregnancy & Birth

Back to basics: conception

Getting to know your cycle is essential when trying to have a baby, with only a small window of opportunity each month. Here’s how to better understand your fertility.

Karen Burge 
July 2018

Making a baby isn’t just about well-timed sex. There are plenty of things going on in your body, and your partner’s, that need to work in sync.

For starters, a healthy sperm needs to travel to and penetrate a healthy egg, which needs to successfully implant in the lining of the uterus.

But even for healthy couples having regular, unprotected sex, it can take months, a year, or longer to fall pregnant.

Dr Wendy Burton, chair of the Royal Australian College of General Practitioners Antenatal and Postnatal Care Specialist Interest Network, says ideally, couples aren’t time pressured, are having frequent sex without contraception – because it’s fun – and along the way they fall pregnant.

“If there’s time pressure, then having sex 3-4 times a week from the end of the period for a couple of weeks (in an average 4-week cycle) covers them very well.”

Your ‘fertility window’

If you want to give yourself the best chance of conceiving, get familiar with your cycle – specifically, the all-important days when pregnancy is possible (known as ‘your fertility window’).

The Fertility Society of Australia (FSA) explains that conception is only possible from about 5 days before ovulation through to the day of ovulation. These 6 days are your fertile window and reflect the lifespan of sperm (5 days) and the egg (24 hours).

The likelihood of conceiving is highest if you have sex in the 3 days leading up to and including ovulation, the FSA says.

“If a woman has sex 6 or more days before she ovulates, the chance she will get pregnant is virtually zero. Then, the probability of pregnancy rises steadily and is 27-33% in the 3 days leading up to and including ovulation."

“From that point, the probability of pregnancy declines rapidly. Twelve to 24 hours after ovulation, a woman is no longer able to get pregnant during that cycle.”

But how do you know when you’re ovulating? This will depend on the length of your cycle. If, on average, you have a period every 28 days, you’ll ovulate at around day 14 and your best chances of getting pregnant are between days 11 and 14.

Mucus change is a good early indicator that ovulation is approaching, although you can also use an ovulation kit (available from your supermarket or pharmacy) or phone apps that can help track your fertile window using your menstrual cycle data. 

Fertility factors

Along with timing, there are other influences that can improve (or hinder) your chances of falling pregnant. Here are a few lifestyle factors to consider:

Try to stick to a healthy diet and keep up your fruit and veg intake

Dr Raphael Kuhn, who is a recently retired IVF specialist and author of IVF Success. An Evidence-Based Guide To Getting Pregnant And Clues To Why You Are Not Pregnant Now, says diet is an important consideration.

“A Mediterranean-style diet and avoidance of processed or pre-packaged food and high sugar content products – such as soft drinks and fruit juices – is associated with a shorter time to achieve a pregnancy.”

Australian research published in the journal Human Reproduction (2018) found that having a diet low in fruit and high in fast food during the pre-conception period were associated with a longer time to fall pregnant. The study involved 5,628 first-time mums and was conducted by the University of Adelaide.

Reduce excess weight

Being in the healthy weight range increases your chances of conception. “If a woman’s weight drops 5-10% prior to pregnancy that can improve her fertility rate. Carrying excess weight means it can take a lot longer to get pregnant,” explains University of Newcastle Professor in Nutrition and Dietetics, Clare Collins.

“If dads aim to shape up prior to pregnancy also, it improves erectile function, even within the normal range, and this is important in being able to conceive. Men who are overweight are 20% more likely and men who are obese 30% more likely to be infertile.”

Factor age into your family planning

Fertility declines with age for both men and women. “For women, fertility starts to slowly decline when they’re in their early 30s. Around age 35 the decline speeds up and by age 40 the chance of conceiving has fallen by half.

The biological reason for this is that as women age, the total number of eggs in their ovaries and their quality decline,” the FSA explains. The monthly chance of conception decreases from 20% for women aged 30 to 5% for women aged 40.

When to seek further advice

If you’ve been having unprotected sex without any pregnancy luck, then your GP is the best starting point for advice.

Dr Burton explains that your timing of the visit depends on a few factors. “Couples/women are always welcome to discuss their particular situation with their GP to get tailored advice.

“As a rule of thumb, women in their early 30s or younger can wait 12-18 months, women in their mid-30s and above should be seen at the 6-9 month mark.” 

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