Tick, tick, tick. For women planning to one day have children, that is the sound of the biological timekeeper counting down the number of years, months or days they have left.

For the most part, fertility is determined by our genes. Of the 1 million to 2 million eggs a woman is born with, just 400 will ever mature and as both women and men age, the quality of the sperm and the egg will decline.

There are, however, ways to protect and boost reproductive health for both women and men trying to conceive and for those who think they might one day want to.

''The older you get, the longer you will have had the opportunity to be exposed to fertility-reducing conditions,'' says Devora Lieberman, a fertility specialist with Genea, formerly Sydney IVF.

''Your eggs and ovaries will continue to age along with you but you also have longer times to experience things like pelvic infections and endometriosis that can affect fertility.''

Lifestyle factors such as weight gain can also make conceiving more difficult and habits such as smoking cause long-term damage, ageing the ovaries by up to a decade.

''It is not OK to say I will smoke in my 20s and then give up in my 30s when I want to have a baby,'' Lieberman says.

Paying attention to genetics, such as the age your mother is when she reaches menopause, can help but according to Lieberman, there is no magic wand to determine how much time a woman has left.

''There are plenty of women with normal ovarian reserves who struggle to get pregnant and a lot with low reserves who get pregnant very quickly,'' she says.

''There are so many other factors involved, such as egg and sperm quality.

''There is no test any of us can do to tell us whether a woman is fertile. We can sometimes tell if she will be infertile or a challenge but my best advice is to start trying.''

IN YOUR 20s

Biologically at least, a woman in her mid-20s is at the ideal age to conceive.

For most, however, babies are still a distant possibility. Women and men in their 20s who plan to have children now or in the future can still take steps to safeguard their reproductive health.

''The most important thing is that the woman is only half the baby and sperm problems are the most common reason for couples seeking IVF treatment,'' says the director of Fertility First in Sydney, Anne Clark.

''Guys forget that sperm cells are not made magically; the cells that turn into the sperm are affected by what they do to their body throughout life.''

Which means that both men and women in their 20s who plan on having children either now or later should maintain healthy habits, such as avoiding excessive weight gain, avoiding recreational drugs, not smoking and practising safe sex, because some sexually transmitted infections, such as chlamydia, can lead to fertility problems if untreated.

For women, the pill is both a contraceptive and a protector of reproductive health.

''It reduces menstrual blood flow and so lowers the risk of endometriosis, tubal disease and ovarian cysts,'' Clark says.

''If women have these, they will develop at a slower rate.''

Some women in their 20s also consider freezing eggs when theirs are in peak condition, most commonly for medical reasons - such as chemotherapy or a genetic predisposition - that mean they will one day require IVF to screen affected embryos.

Frozen eggs, however, still have a low success rate when it comes to conception.

IN YOUR 30s

For many women, looking after their fertility and reproductive health is something that starts only when they want to have a baby, which for most Australians is some time after they turn 30.

It might be the ideal time emotionally, socially and financially to have a baby but physically they are likely to have to work a little harder than most twentysomethings to conceive. Again, Clark points out that the health and age of the father should be given equal importance.

''From the mid-30s on, a man's level of sperm DNA damage increases,'' she says. ''If you look at miscarriage risks, if you have a woman in her early 30s whose partner is 40 or older, her chance of miscarriage is three times higher.''

Many women will discover conditions that affect fertility, such as endometriosis or polycystic ovarian syndrome (PCOS), only when they start trying for a pregnancy.

Medical treatments such as surgical laparoscopy and prescription drugs are available to treat these conditions, however, an increasing number of young women are also looking to alternative medicine.

The director of the Acupuncture IVF Support Clinic in Sydney, Jane Lyttleton, says acupuncture can both help restore ovulation frequency and treat some of the other symptoms of PCOS, such as acne and excessive body hair, while Chinese herbal medicine and acupuncture can treat the symptoms of endometriosis.

''More and more young people with PCOS are coming in to us with a view to preserving fertility,'' Lyttleton says.

''Younger women with endometriosis will also seek out Chinese medicine.''

The average age of Lieberman's female patients is just over 38 and most have been trying to conceive for at least a year.

She says that while some prefer to see a naturopath or an acupuncturist first, a fertility specialist can determine whether there are any obvious barriers.

''There are simple steps such as a semen analysis and ultrasound,'' she says. ''The next steps are up to the couple. It is shame to spend six months going down that path and then find out there is a problem.''

IN YOUR 40s

Contrary to the myth that women trying to conceive in their 40s have given priority to their careers and mortgages, Lieberman says the most common reason is women finding the right partner.

''The vast majority of women I see in their late 30s and early 40s say it took them that long to find a man they want to have children with,'' she says.

While stories of celebrities falling pregnant in their late 40s are popular with the media, experts agree that in reality, these cases are rare. By the age of 42, a woman's chance of falling pregnant using her own eggs is greatly reduced.

For those who find themselves in that situation, using donor eggs is one option. However, single women wanting to use their own eggs do have an advantage, according to Clark.

''A single woman in her 40s has the advantage of having a younger partner - all donors are under the age of 35,'' she says.

For those undergoing IVF treatments, acupuncture and Chinese herbal medicine can help.

''There are some trials done that show acupuncture can increase implantation rates,'' Lyttleton says.

''It also reduces some of the side effects of IVF treatments, such as bloating, back ache and headache.

''Most women tell us they come because they feel so good afterwards; it helps them to cope better with the treatment.''Fertility boosters

Don't smoke. Almost one-third of fertility problems are related to cigarette smoking.

Maintain a healthy body weight.

Avoid excessive alcohol and caffeine and don't use recreational drugs.

Eat foods rich in folate (including asparagus, bran flakes, broccoli, oranges and spinach).

Eat foods rich in iodine (including fish, bread, dairy products and eggs) and take supplements.

Ensure you take adequate vitamin D.