Fertility facts you need to know

Between 30 and 40 years, a woman’s chance of having a baby each month (if conceived naturally) falls from 22% to 6%.  Even at your most fertile age, you will only ever have a 25% chance each month(3). The average age of a woman’s first birth in New Zealand is 30 years(1), however, a third of the women we see as patients are now over the age of 40.

For some, this is due to the fact that travel and career have meant that starting a family has been put to one side; for others it may be they have not met the ideal partner just yet.  For others, it may be that they have been trying for a while now without any luck, but are not sure whether they should talk to a specialist now or wait a little bit longer.

Our key message is that fertility does not follow social trends – it’s hardwired into your DNA. Even though we are living longer than our ancestors, the fertility window for a woman remains the same, even if she is fit and healthy. Surveys have consistently shown that people over-estimate how long their fertility will last by about 10 years.  In addition, there is a widespread belief that treatment like IVF can overcome the effects of age. This is constantly reinforced by the glossy magazines who when profiling celebrities having babies later in life, often fail to declare that an egg donor was involved.

As you get older, you have less time to wait and see. Time waits for no woman (or man) – if you’re 30 and wait for 2 years your chance of a baby with IVF falls from 48% to 46%, but if you’re 40 and don’t do anything for another 2 years your chances with IVF drop from 23% to 13%!

With most women aged 36(2) and over when they first come to see us, the time to act if you have concerns about your fertility is NOW!

Commonly asked questions:


Comparing your 40's to your 30's:

Your fertility In your 40s In your 30s
Chance of a baby per month (natural conception) * Live birth

Woman aged
40 - 6%
43 – 2%
46 – < 1%

49 – 0%

Woman aged
30 – 22%
33 – 19%
36 – 15%

39 – 8%
Chance of a baby per IVF cycle * live birth

Woman aged
40 - 23%
43 – 8%
46 – 4%

49 – 0%, would need an egg donor

Woman aged
30 – 48%
33 – 45%
36 – 38%

39 – 28%

Impact of age

The quality of a woman’s eggs and her ovarian reserve decline with age.  Most women go into menopause between 50 and 55, approximately 10 years after their fertility ceases.  There is also an increased risk of genetic abnormalities as the woman ages.
In regards to men, being aged over 50 is associated with a longer time to conceive, seperately from the effect of his partner's age.  This doesn’t happen if using IVF as the number of sperm around the egg is greatly increased.  There is also a moderate increased risk of genetic abnormalities as the man ages.

Impact of lifestyle –female and male

Poor lifestyle can reduce fertility, but a healthier lifestyle cannot compensate for the impact of age
Publicly funded treatment Unfortunately public funding does not cover the cost of treatment for women aged 40 years and over.  You must have been assessed and if eligible, enrolled for a publicly funded consultation or treatment before you turn 40. You are eligible to be accessed for a publicly funded consultation and/or treatment up until the female in the partnership turns 40 yrs.  As long as you meet the criteria as set by the Ministry of Health.

(1) Statistics New Zealand
(2) FAA private patients and FAW public and private patients
(3) This number shows the chance of a live birth per month.