But experts are warning that when pregnant women are going through the last stage of pregnancy, their immune system is compromised.
And they are at a greater risk of contracting STIs.
According to nurse practitioner and STI expert Terri Warren, the biggest risk is when a woman contracts herpes in her third trimester.
The author of The Good News About The Bad News: Herpes: Everything You Need to Know, told Vice that babies have a 50 per cent chance of being born with the disease if their mothers contracted it during pregnancy.
Joe Aquilina, a consultant obstetrician at the Royal London Hospital, said he agrees with Ms Warren, and would suggest pregnant women ‘avoid oral sex’.
‘If the father has a cold sore around the lips and they engage in oral sex, she could get a primary infection.’
To reduce the chance of this infection passing to the baby, he said he would not advise having a natural birth.
Dr Aquilina said: ‘If the woman had a primary infection I would advise erring on the side of caution and having a c-section.’
Even if a condom is worn, STIs can still be transmitted. It can provide a barrier for fluids but it does not stop all skin-to-skin contact, leaving a risk of infection from HPV, herpes, syphilis, pubic lice, or scabies.
As such, STI experts advise the safest way to avoid infecting a pregnant mother is to stay clear of oral sex altogether.
It follows the news from a leading psychologist who claimed the best way to treat morning sickness is by giving oral sex and consuming semen.
Prof Gordon Gallup said pregnant women who consume the sperm of their baby’s father are less likely to feel sick when they wake up.
He claimed morning sickness is caused by the introduction of a foreign substance – in this case semen – to a woman’s body and the more sperm a woman ingests, the more tolerant of it she will become.