The virus has been linked to thousands of babies being born with underdeveloped brains and has been spreading on a massive scale in the Americas.
UK officials say women can talk with health professionals about the risks.
If travel is unavoidable, they should take precautions to avoid bites from mosquitoes that spread the disease.
Women planning to become pregnant should also be wary, says the National Travel Health Network and Centre.
Any pregnant woman who has recently travelled to a country where Zika is known to occur should tell their doctor or midwife.
The UK Foreign Office says people can search its website by country or territory to find out the latest situation.
The World Health Organization says the virus is likely to spread across nearly all of the Americas, apart from Canada and Chile.
Three Britons have already contracted the virus after travelling to South and Central America.
A spokeswoman from UK travel organisation Abta said women reconsidering their plans would be able to get a medical certificate from their family doctor in order to claim on insurance.
US experts at the Centres for Disease Control and Prevention say insect repellents containing active ingredients, such as DEET and picaridin, are safe for pregnant and breastfeeding women.
To lower the risk of infections spread by mosquitoes, pregnant women should use insect repellants, stay indoors during peak times of mosquito activity (usually dawn and dusk) and wear protective clothing (such as long-sleeve shirts, long pants, and socks).
Zika is transmitted by the Aedes mosquitoes. The infection often occurs without symptoms but can cause an illness similar to dengue.
Symptoms include:
Patients usually get better on their own, but the big concern is the damage the virus might do to an unborn child.
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Pregnant Britons are being advised to reconsider travel to areas where Zika virus outbreaks are happening.