Free online calculator will allow couples to prepare emotionally and financially for their chances of conceiving using IVF.

Today the average Kiwi woman will have her first baby at 28, but this was not always the case.

Before World War II the average age for a first pregnancy was steadily increasing until the post war generation experienced a two decade long baby boom which embraced domesticity, early marriage and early childbearing.

It wasn't until the 1970's that the average age started to increase again and today more women are waiting until their 30's and 40's to start their family.

This becomes important when it comes to fertility issues as research shows that after 30, a woman's chance of having a baby starts to decline and will continue to decrease with age.


Two of the common reasons given by women for why they wait before having children are career progression and further education, but this increasing in age is causing more women to seek medical help for fertility issues.

According to research in the New Zealand Medical Journal, one in four couples in New Zealand has problems with fertility or needs medical help to conceive.

Recently technology has been able to play a positive role for fertility problems with in vitro fertilisation (IVF) being responsible for tens of thousands of successful pregnancies, especially in older women.

IVF is a process where an embryo is grown in a lab after artificially fertilising the egg with the sperm in a petri dish. Embryos that survive for 3 days outside the body can then be transferred into the woman's uterus resulting in pregnancy if they implant successfully.

Although IVF is a highly technical procedure, the prediction model for the success of the treatment is still relatively basic and difficult to access.

Thanks to a new study published this week in the British Medical Journal access to IVF prediction tools are about to become easier after a new data driven online IVF calculator was created.

The calculator uses algorithms based on the BMJ study which analysed data from 113,873 women over 118,000 IVF cycles and includes information on the number of eggs produced, number of fertilised eggs, number of successfully transferred eggs and the number of live births. Although it doesn't take into account information like lifestyle factors and BMI, it is unique in its ability to calculate probabilities using fresh or frozen eggs.

Data analysis found the factors which have the biggest impact on the success rate of IVF treatments include the age of the woman, the number of eggs produced from her cycle, whether the egg was fresh or frozen and the stage at which the fertilised embryo was transferred into the uterus.

Of the 113,873 women analysed, 29 per cent had a live birth following their first cycle and 43 per cent had a baby after six cycles of treatment. Interestingly the data showed that a higher pregnancy success rate occurred when more eggs were produced from a cycle only up until 13 eggs, after which the egg quality deteriorated which made them less likely to become healthy embryos.

In New Zealand IVF is an expensive process and for couples who can't obtain publicly funded treatment each cycle can cost over $10,000. With access to this free IVF calculator, patients can now use evidence based data to predict the number of cycles they might to need to fund helping them to both emotionally and financially prepare for the treatment.

With one in every 25 babies born in New Zealand being the result of IVF treatment, tools like this calculator may help patients to gain a more personalised and realistic perspective on their IVF experience and see data from other couples like them.