According to The Sun, Harry Ashby, 29, has become the first man to be officially signed off with the condition.
He says he suffers from a condition that mimics wife-to-be Charlotte Allsopp's pregnancy – including morning sickness.
Since his partner became pregnant Harry has put on half a stone in weight, gained a belly, and had back pain and peculiar food cravings.
In Harry's case, his diagnosis came as the Duchess of Cambridge, who is pregnant with her second child, has bowed out of official royal engagements due to morning sickness.
He said: "My morning sickness had prevented me going to work. I can imagine how the Duchess feels about missing her royal duties."
Talking of his cravings, he said: "I'd ring asking Charlotte what she was having for lunch. She'd say salt and vinegar crisps, and I'd be eating them at the same time - I normally hate them."
Security guard Harry has been given medication to help him battle the symptoms and it has been claimed that he can also claim benefits while off sick.
The baby is due on January 2, but it has been reported that Harry began getting symptoms two months after finding out Charlotte, 19, was pregnant.
Initially the pair thought Harry was suffering from a bug, but after he continued to complain they began researching his symptoms.
Following an internet search, the couple thought Harry might be suffering from Couvade syndrome, known as sympathetic pregnancy - which was confirmed after a visit to their GP.
Harry said: "I was shocked. I've been told I'm the first man in the UK to be signed off work for being pregnant."
The couple believe Harry's condition could have been sparked by the pain of Charlotte losing a baby in 2012.
She fell into a depression but seven months on found she was pregnant again.
Charlotte said she was pleased he was going through the same experiences as her as it would show him what being pregnant was like.
She said: "I do get a bit tired of having to look after Harry when he should be looking after me. It proves women are tougher than blokes when it comes to pregnancy."
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