John Speraw
American men's volleyball coach John Speraw is freezing his sperm before the Rio OlympicsReuters/Lucy Nicholson

While the World Health Organisation has insisted that there's a "very low risk" of further spread of the Zika virus at the Rio Olympics, at least one coach and another athlete are considering freezing their sperm beforehand just in case.

Several athletes have already decided to skip the games entirely to avoid the risk. UK gold medalist long jumper Greg Rutherford was the first to announce publicly that while he has decided to participate, he is freezing his sperm first to have an uncontaminated "bank" for future babies.

The Zika virus has been linked to severe birth defects, including microcephaly — an unusually small head and brain development in babies born to mothers who contract the virus. Zika can be transmitted to women via sex with an infected man.

American John Speraw, 44, the coach of the US men's indoor volleyball team, is now also freezing his sperm.

"My wife and I would like to have another kid. And I'm no spring chicken. I don't want to get Zika and have to wait an additional year, or whatever it may be, for us to have kids," Speraw told the New York Times. "I'm paying attention to Zika and I'm concerned about it. It's not going to stop me from going down there, but I'm taking measures right now."

In addition, Speraw's wife, Michelle, and their seven-month-old daughter, Brooklyn, will not travel to Rio because of concerns over Zika, he said. A big reduction in the number of friends and family members travelling to Rio to watch and support athletes is one key consequence of virus fears.

Spain's Pau Gasol — the 35-year-old centre for the Chicago Bulls basketball team — is also seriously considering freezing his sperm if he decides to go to the Games. "Freezing sperm is one of the measures I have to consider," he said, Associated Press reports. Gasol hasn't yet committed to going to Rio for Spain.

"We are constantly learning more but there is uncertainty about how long the virus remains in one's blood," Gasol said. "We can't take this health threat lightly. It doesn't just affect pregnant women."

In the latest news about Zika, the US Centers for Disease Control and Prevention has revealed that 234 pregnant women in America had the Zika virus by the latest count, with half of the pregnancies still ongoing, ABC reports.

The virus has already been linked to birth defects in babies and fetuses of six women in the US.

Three of the women have given birth to infants with birth defects linked to Zika, such as microcephaly and brain damage, the CDC said, citing data reported to its US. Zika pregnancy registry as of 9 June.

Three others lost babies with birth defects, either through miscarriage, stillbirth or pregnancy termination.

All infections were travel related. Most of the women contracted the disease in a country where Zika is spreading. At least two of the cases were linked to sexual contact with a partner who had traveled.