Menstruation is not a topic that is mentioned openly in the sporting world. So, when China's Olympic swimmer Fu Yuanhui talked about it, her comments went viral.

When asked about her team's fourth-place finish in the medley relay, she said she was not at her best as she was having her period and had felt "particularly tired", though she added that it was not an excuse for not swimming well.

It led some people to question whether women should even swim when they are having their period.

The answer is, yes, of course, but precautions have to be taken.

The counter-pressure of the water may prevent blood from flowing out of the body but it does not slow down or stop your period, said Dr Christina Low, medical director at Lifescan Medical Centre, which has three clinics here.

"If your flow is heavy and you will be in and out of the water, your best options are internal feminine hygiene products such as tampons or menstrual cups," she said.

Tampons absorb menstrual flow. Menstrual cups collect the flow.

Both have to be inserted into the vagina, but the menstrual cup - a flexible, bell-shaped cup that is mostly made of sillicone or rubber - requires a little bit more skill to insert and remove.

"If you are one of the fortunate women who stop bleeding immediately when you are in the water (because of the counter-pressure of water) or are flowing very lightly, it may not be necessary for you to use feminine hygiene products."

However, it is still wise to keep your pad or tampon nearby to catch any leaks once you get out of the water, Dr Low added.

If you are just lying in the sun by the pool and are not getting in, you can opt to wear a pad or a liner (for very light flow), she said.

"I'd advise against swimming with a sanitary pad or even a panty liner because they are designed to absorb moisture. They will get soggy when you get into the water."

Using a pad in the swimming pool also means that there is a chance that your menstrual blood may contaminate the pool water, said Dr Low.

Nevertheless, women do not need to fear that they will turn the water in an Olympic-sized pool red.

If your period is light, menstrual blood will take a while to flow out of the body and the flow may not be significant, said Dr Elisa Koh, an obstetrician and gynaecologist at Mount Elizabeth Novena Hospital.

She said: "If the flow is light, you may not even be able to see it clearly. It's very hard to see a few drops in the ocean."

But for hygiene purposes, it is best to wear a tampon if you want to swim when you are having your period, she added.

Like the Olympic swimmer Fu, other female athletes may find their performance affected by the symptoms of their monthly period.

Severe pre-menstrual and menstrual symptoms, such as cramps and heavy bleeding, may hamper a person's mood and affect her performance, said Dr Low.

What women can do is to take pain-relievers like Neurofen or Ibuprofen, though in some cases, simply getting into the water and distracting yourself will help you forget about the pain, cramps or discomfort, she said.

Studies have shown that women feel less menstrual pain when they are active, said Ms Michelle Kwong, a physiotherapist at Physioclinic.

They can also do some stretching exercises to help minimise the pain and discomfort, she said.

In short, your period should not be allowed to take over your life, said Dr Koh.

"If the pain prevents you from going to work, or if you throw up or faint due to the pain, you should see a gynaecologist to control the symptoms," said Dr Koh.

Severe pain could be a sign of a medical problem that should be addressed, she said. For instance, certain ovarian cysts can cause bad period pain.