Career, cost, and the missing ‘Mr. Right’ make it tempting to ‘put off’ having a baby, but there’s a price to pay for postponing pregnancy. Dr Gillian Lockwood, Medical Director of the Midland Fertility Services looks at the affect age has on fertility

Compared to our grandmothers’ generation, today’s thirty and forty-somethings look and feel so young and healthy that, it is difficult to remember that their reproductive life-span is just as short as it was one hundred or one thousand years ago. 30 years ago, the average age of new mothers was 26. Now it is 30 and climbing rapidly.

• 12% of births in the UK are to women aged 35 or over (a 50% increase in a decade)
• First babies born to women over 35 now account for 7% of all UK births.

• Even young couples with normal fertility (and trying quite hard) have only a 25 – 30% chance of establishing a pregnancy each month they try.
• When a woman reaches her mid-30’s, this monthly chance drops to 10 – 15%
• By her early 40’s it is less than 5% a month AND she is facing a 40% chance of miscarriage even if she can achieve a positive pregnancy test.

Since fertility is to a large extent genetically inherited, a woman can get a good idea of her likely reproductive prospects by finding out about her mother’s experience. If her mother had difficulty getting pregnant after her late twenties and had a relatively early menopause (younger than 45 – 50years) there is a chance that her daughter may experience similar problems. Women whose mothers and grandmothers had babies effortlessly in their late thirties or early forties may be reassured that they will probably be able to do the same.

Health and lifestyle factors play an important role in influencing a woman’s natural fertility:

• Smoking is probably the single most significant factor — women who are life-time smokers will undergo their menopause approximately 5 years ahead of schedule and will become sub-fertile sooner and have a higher risk of miscarriage.
• Women who are significantly below or above their ideal weight are also at a higher risk of fertility problems and/or pregnancy complications.
• Women who have had pelvic surgery, endometriosis or recurrent pelvic infections also seem to have a lower chance of successful pregnancy, probably because their store of viable eggs is reduced.

Fertility treatments

Intra-Uterine Insemination

Some women trying to conceive later in life may be helped by fertility treatments such as Intra-uterine Insemination (IUI) in conjunction with ovarian stimulation. Stimulated IUI is a treatment designed to enhance a couple's natural fertility without resorting to 'high-tech' treatments.

The woman undergoes stimulation with gonadotrophins (hormone injections) to encourage 2 or 3 eggs to mature. Throughout the drug phase, treatment is monitored by ultrasound and when the follicles are ready, a final injection of hCG is given to provoke ovulation.

Approximately 30 – 40 hrs later, specially prepared sperm (ideally 5 million, highly active sperm) are inserted through the cervix in a fine plastic tube and deposited high up in the uterus, near to the opening of the Fallopian tubes. Putting very good sperm in exactly the right place at the right time boosts natural fertility. Success rates with stimulated IUI are typically 10 – 15% per cycle.

In-vitro fertilisation

Many women in their late thirties or early forties choose to have IVF treatment even if there is no apparent explanation for their failure to conceive other than their age. IVF is recognised to be an effective (and diagnostic) treatment for this so-called ‘unexplained’ infertility. Women in this age range are also acutely aware that their biological clocks are running down very fast and they cannot risk waiting (or wasting!) another 6 months to ‘give Mother Nature another chance’ since success rates of fertility treatments such as IVF depend on the age of the woman concerned.

For more information see other related articles:
The cost of IVF
IVF - what you need to know.

The success rates for IVF (approximately 25% per cycle for women under 40 and 15% per cycle for 40+) depend upon a woman having good ‘ovarian reserve’, that is being able to recruit a good number of ovarian follicles in response to the stimulating drugs used in IVF. Assessing ovarian reserve is therefore a very important part of counselling a couple about their individual chances of success with ‘high-tech’ fertility treatments such as IVF. Age, past medical history, FSH (follicle stimulating hormone) levels and ovarian scan results all provide useful information for predicting the likely chance of success with treatments such as IVF. In addition, some fertility specialists are now advising women to have their inhibin B level assessed. This simple blood test, (taken during day 3-6 of the menstrual cycle), provides a direct measurement of ovarian reserve.

The future

It is now possible to freeze human eggs and then thaw them and use them to generate embryos for transfer in an IVF cycle. At the moment this technology is mainly used to help young women who are facing a diagnosis of cancer. Lifesaving chemotherapy or radiotherapy will probably render them sterile and the technique of egg freezing allows them to ‘bank’ their oocytes (eggs) for later use, so that they have a chance of giving birth to their own genetic children.

This same technology could be applied to allow young women who were not yet in a position to become pregnant to store their eggs for use later when they wished to start a family. Clearly this new approach to ‘family planning’ may meet with some resistance. For future generations though, it could offer a solution to the ‘career women’s’ dilemma about when to start a family.

For more information look at Infertility treatments what the future holds.