Time’s running out if you’re thirty-something and want to have a baby. Dr Gillian Lockwood , Medical Director of the Midland Fertility Services, tells you how to preserve your fertility

We have to face it - human beings, as a species, aren’t very fertile. To be blunt, once you reach your mid-thirties, your chance of getting pregnant is 10-15% each month and by your early forties it’s less than 5% a month. Plus you’re facing a 40% chance of miscarriage if you get a positive pregnancy test.

As you get older your ovulation pattern can become less predictable and your monthly cycles shorter. This means you have a shorter pre-ovulation phase and so your ‘fertile window’ occurs earlier in your cycle.

More depressing statistics to come

Your chances of success will be lower if you or your partner have problems with irregular ovulation or poor sperm quality. And the risk of chromosome abnormalities, such as Down’s syndrome, increases rapidly for couples in their late thirties. Find out more about your age and fertility.

It’s not all gloom and doom

Fertility is to a large extent genetically inherited, so you can get a good idea of your reproductive prospects by finding out about your mother – a chance to pry! If your mother had difficulty getting pregnant after her late twenties, and had a relatively early menopause (younger than 45-50years), there’s a chance that you may experience similar problems. If your mother or grandmother had a baby effortlessly in their late thirties or early forties, you’ll probably be able to do the same.

A blood test can also help to assess your fertility

Many fertility specialists now advise women to have a blood test to assess their inhibin B levels. Inhibin B is a hormone produced by the ovaries and it’s a useful predictor of the way the ovaries will respond to stimulation during fertility treatment. It can also gauge your spontaneous fertility and provide vital information about whether you can ‘safely’ postpone trying for a baby for a few years, or whether your ‘ovarian reserve’ is already low and you need to get a move on. It’s a simple blood test taken during days four to six of the menstrual cycle.

Fertility treatments can help some women

Women in their forties are acutely aware that their biological clocks are running down fast, and they can’t risk waiting (or wasting!) six months to ‘give Mother Nature another chance’. It’s wise to get help sooner rather than later and, given the limited amount of fertility treatment available on the NHS and the long waiting lists, you may have to consider going private if you can afford it. See – fertility treatment - the postcode lottery.

Intra-uterine Insemination (IUI) in conjunction with ovarian stimulation can help some women who want to conceive later in life. Intra-uterine insemination with ovarian stimulation boosts the chances of getting pregnant by increasing the number of eggs released each month and ensuring that high quality sperm are in exactly the right place at the right time. The woman has daily hormone injections to stimulate her ovaries which are monitored by ultrasound. When two or three good follicles have developed, ovulation is triggered with an injection of HCG (human chorionic gonadotrophin) - a hormone used to stimulate ovulation which helps the egg mature within the follicle and promotes its release). Two days later her partner produces a sperm sample from which the most active sperm are selected. They are then passed into the cavity of the womb through a fine plastic tube and deposited high up near the opening of the fallopian tubes. Success rates with stimulated IUI are typically 10-15% per cycle. The relatively aged egg seems to prefer the gentle stimulation and the in vivo rather than in vitro environment of IUI.

Many women in their late thirties or early forties choose to have IVF treatment even if there’s no explanation for why they haven’t conceived. The success rates for IVF (approximately 25% per cycle for women under 40 and 10-15% per cycle for 40+ plus) depend on a woman having good ‘ovarian reserve’, - that is, being able to produce a good number of follicles containing eggs in response to the stimulating drugs used in IVF. If several eggs can be collected (ideally up to six) then there is an increased chance of a pregnancy occurring. We can predict a success rate for IVF – taking into account age, past medical history, FSH (follicle stimulating hormone) levels and ovarian scan results.

Human eggs can now be frozen and thawed later 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 women sterile, and the technique of egg freezing allows them to ‘bank’ their oocytes (eggs) for later use, so they have a chance of giving birth to their own genetic children.

Oocyte cryopreservation

A woman goes through an IVF cycle up to the point where the eggs are harvested. They are assessed for maturity, and then frozen in a special solution that ensures that ice-crystals don’t form. These could damage the eggs.

When the woman wants to have a baby, some of the eggs are thawed out and the ICSI (intra-cytoplasmic sperm injection) technique is used to achieve fertilisation. ICSI involves the micro-injection of a single sperm into each egg using a glass needle about a tenth the thickness of a human hair. The embryo is transferred 2-3 days later and the pregnancy test can be taken after 14 days.

Oocyte cryopreservation is still at a relatively early stage of development and the success rates are not yet as high as they are with conventional IVF. If you’re considering storing your eggs, don’t delay beyond your mid-thirties as every passing year means both the number and quality of the eggs available for storage is reduced. If you go private, Oocyte cryopreservation is available for women who are concerned that they may not be in a position to become a mother until they’re older, when their chances of success are low. However, it’s an expensive technique and success can’t be guaranteed.

Men are different – lucky things

A man doesn’t usually need to store his sperm unless he’s going to have medication which will affect his fertility (treatment for an enlarged prostate gland for instance or chemotherapy) or some kind of serious surgery. Despite some decline in quality and quantity, healthy men go on producing viable sperm into their seventies.