Though Gardner sued Netball Australia and won, and the ban was lifted before the year was out, the organisation still discourages pregnant women from playing. Netball NSW's website bears the following warning: "Netball is a contact and collision sport and is not recommended for pregnant athletes. All persons participating in netball should seek medical and legal advice on this issue."

So just how risky is it for pregnant women to play sports? Does exercise put them and their foetuses in danger?

If all the publicity garnered by Netball Australia's bold move a few years ago did one thing, it mobilised sports physicians, exercise physiologists and researchers to speak up. And their message has been clear: while women may need to modify their exercise regimes, the benefits of keeping fit and active during pregnancy far outweigh the risks.

"Fit women cope better with the delivery and it helps the outcome of the pregnancies," says Anita Green, a GP with a special interest in sports medicine who works at Queensland University of Technology's health service.

"There are two times in their lives when women are most prone to stop exercise: one is at puberty when body image becomes an issue, and the second is during pregnancy, when they become very busy and it's hard to find the time.

"We recommend women continue exercising through the pregnancy for as long as it's safe."

Assuming the pregnancy is progressing normally, she says this means women can continue low levels of exercise throughout most of the pregnancy, depending on the individual's comfort level.

Medical issues such as diabetes or hypertension, or obstetric complications including bleeding, premature contractions, leaking of amniotic fluid and delayed growth of the foetus are other reasons a woman may need to change her exercise routine or stop exercising altogether, she says.

Olympic sports physician Jenni Saunders agrees: "Unless there's (another) medical reason, there's no harm in exercising."

Aside from all the benefits exercise brings to the general population, such as reduced risk of cardiovascular disease, osteoporosis and some types of cancer, women who stay fit and active through their pregnancies tend to have quicker recoveries than their less active counterparts. They are also less likely to gain excessive weight during their pregnancy, and more likely to lose the extra kilos they do gain.

And the benefits aren't necessarily exclusive to the mother. Woman who do moderate exercise regularly have smaller babies -- weighing on average 200g less than others -- and there's no growth retardation or other problems.

The size difference seems to be directly related to the amount of fat the babies have, and recent research suggests that could be an advantage because babies who are obese are more likely to be obese when they grow up, says Green, who is also the immediate past president of Sports Medicine Australia.

Even women who've not previously exercised can benefit from beginning mild to moderate exercise such as walking or swimming, so long as they consult their doctor first, according to the Australian Sports Commission's Pregnancy in Sport guidelines.

For competitive sportswomen who maintain their fitness, pregnancy can even provide some physiological advantages.

"There are endurance athletes who have come back after pregnancies and done very well, even won Olympic gold medals," says Wendy Brown of the University of Queensland's School of Human Movement Studies.

"It's almost like blood doping -- the additional stress from carrying the baby causes your body to make more red blood cells, so you have extra oxygen-carrying capacity."

Common sense and caution are keys to a healthy, safe pregnancy.

When it comes to pregnancy and exercise, even the most commonly held assertions are based on theory, rather than absolute proof.

"There's not much reliable research out there because it's not possible to do properly controlled trials -- one study got a group of women and asked some to cut down their training and others to increase theirs and attempted to track the results, but it didn't work because the women didn't comply," Brown says.

"Studies have also been done on sheep on treadmills, but that has its limitations, too, since they are horizontal and have a woolly coat, so those are important factors when it comes to heat control."

So with that in mind most advice errs on the side of caution. Pregnant women are advised to avoid overheating, because heat can interrupt the development of the foetus and cause deformations, though there's no concrete evidence to prove that exercise-related heat has this effect.

"We've based that idea from people who have had fevers or stayed too long in spas who have had higher rates of deformations in their babies. So based on that we tend to say that women should avoid high core temperatures, especially in the first trimester because most development occurs in the first 17 or 18 weeks," Green says.

Doctors say women should avoid exercising at very high intensities later in the pregnancy because blood flow to the placenta goes down during exercise, and studies in animals have shown that large amounts of highly intense exercise over prolonged periods of time can rob the placenta of blood and cause gross retardation. Again data is limited.

"There's nothing to say definitively that it's not safe, and nothing to say that it is," Green says. But to avoid the risk, doctors say pregnant women should keep their heart rates below 75 to 80 per cent of their maximum.

In the first trimester the biggest risk to the baby comes from overheating, while in the second and third trimesters, trauma is more of an issue.

But that said, trauma from sport is incredibly rare.

"The chances of having a miscarriage from playing sport are very low -- there has never been a case in Australia," Green says.

"Most miscarriages that occur at this stage (the second or third trimesters) due to trauma are a result of motor vehicle accidents or violence.

"We tend to recommend women be cautious about contact sports after the first trimester."