Whether or not this statistic holds true in your workplace, there may be a few sheepish expressions the morning after.

Unfortunately, Christmas party sex often means drunken sex, and that in turn can mean unsafe sex. Given the risk of unwanted pregnancies and ITS - not to mention cases of sexual harassment and assault - how can people ensure that regrets are kept to a minimum? And should employers be doing more to safeguard their employees' sexual health?

Employers should be proactive

According to Stephen Bitti, managing director of Nudge Associates, employers need to think about this issue in terms of minimising risk. His company, which delivers health and well-being training to businesses, focuses on sexual health in particular and believes the discussion needs to be destigmatised in the workplace.

"People don't necessarily feel comfortable talking about sexual health with their colleagues, and this can be systemic throughout the organisation. But employers can take a proactive approach to promoting respect, and ensuring the appropriate signposting is there for people to access support," he says.

As he explains, people might have concerns about finding a sexual health clinic, or taking time off work for a check-up. They might also worry about confidentiality being broken, or reactions from their peers.

"Employers need to create a space where people feel they can be open about sexual health issues, and that it's OK to have a check-up," he says. "This has advantages for the employer as well as the employees - there's a benefit to employers when you consider the costs of sickness absence, and how much that can be reduced by engaging with people. Having a briefing pack to raise awareness and safety at Christmas parties is the first step in the right direction."

David Hession, an employment law solicitor at Simpson Millar LLP, says that while there is no set legislation surrounding office Christmas parties, employers should be mindful about what can happen when drinking gets out of hand. In a worst-case scenario, this might include sexual harassment claims.

"During a recent case, an employee tried to bring a claim against an employer following a physical assault by another employee, which took place in a hotel after the annual Christmas party," he says. "The employer was not held liable, but the case did outline the principle that office parties can be seen as an extension of the workplace."

He adds that, short of not holding a Christmas party at all, there are some sensible practical measures that employers can take.

"This could involve restricting the level of free alcohol that is available. For instance, they may want to make free beer and wine available but not spirits. Employers should also have a written policy in relation to employees' behaviour at social events," he says.

Of course, employers can't prevent office romances from blossoming, and they have no right to police people's sex lives. However, they do have a duty to prevent employees from sexual harassment in the workplace (which includes office parties) and they can create an environment that makes it easy to find support.

As for employees? As Natika Halil, chief executive of the sexual health charity FPA, explains, there are plenty of ways people can enjoy the party atmosphere while protecting themselves from the risks.

"Knowing your own limits with alcohol will help reduce the risk of anything happening that you might regret, and it's important to make sure you have clear, active consent from anyone else who's been drinking," she says. "If they're not sober enough to clearly give consent, then they're not sober enough to consent at all."

She adds that, since you don't necessarily go out expecting to have sex, it's always good to have a game plan and carry condoms with you.

"If you're out without a bag, or with no pockets, pop a condón somewhere else: in your shoe, sock, bra, or even in your pants. Just make sure it's not somewhere that could damage it! Remember, if you're on the pill, to take it well before you start drinking, so if you're sick your contraception will still work," she says.

She adds that, where unprotected sex has occurred, it's best to try to take an emergency contraceptive pill as soon as possible (certain pills can be used up to 120 hours after unprotected sex). STI checks are also important, even if you don't have symptoms.

As Bitti points out: "There are ever increasing numbers of STIs in the UK. So it's important that people take responsibility for their actions and take part in regular sexual health screenings if they're sexually active."