Expectant fathers can suffer from pregnancy symptoms, UK research shows.
Morning sickness, cramps, back pain and swollen stomachs were all reported by men whose partners were pregnant.
Researchers at St George's University, London, who carried out the study of 282 Dads-to-be said the phenomenon was known as "Couvade syndrome".
Experts said it was not clear why some men had similar symptoms to their partners but it could be related to anxiety over the pregnancy.
Specialists monitored the men, aged between 19 and 55, whose partners attended St George's Hospital during their pregnancy and compared the findings with a similar number
Expectant fathers reported a range of symptoms, including cramps, back pain, mood swings, food cravings, morning sickness, fatigue, depression, fainting, insomnia and toothache.
In more extreme cases, men developed swollen stomachs that looked like a "baby bump".
Eleven of the men went to their GP about their symptoms but no physical causes were found.
Most men noticed symptoms in the early stages of their partner's pregnancy. Others had to cope with problems right up until the delivery.
Most symptoms disappeared after the birth.
"These men were so attuned to their partners, they started to develop the same symptoms," said Dr Arthur Brennan, senior lecturer at St Georges, who led the study.
One man in the study said: "I was constantly hungry all the time and had an unstoppable craving for chicken kormas and poppadoms.
"Even in the early hours of the morning I would get up and prepare myself one. It was strange to say the least."
One of the men in the study insisted that the stomach pain he experienced during labour outranked his wife's discomfort.
"It seemed like my pain was worse," he said. "Her contractions were fairly strong, but she couldn't push and as that was happening my stomach pain was building up and up and getting worse and worse."
Couvade Syndrome, comes from the French word 'couver' which means 'to hatch', but is not a recognised medical condition.
Dr Brennan, a father of two, said he noted it while studying foetal and paternal attachment earlier in his career.
"Some people may perceive this as men trying to get in on the act, but far from being attention-seeking, these symptoms are involuntary," he said.
"Often the men haven't got a clue about what's happening to them.
"Doctors don't recognise Couvade Syndrome - there's no medical diagnosis.
"Yet this research proves that Couvade Syndrome really exists - the results speak for themselves."
Dr Val Collington, head of the School of Midwifery at St George's, said: "Midwives might not be surprised at these findings.
"One told me that in her experience, men often complain of nausea during the early stages of a partner's pregnancy."
Dr Harriet Gross, senior lecturer in the Department of Human Sciences at Loughborough University said the syndrome had been identified and it was believed to have a sympathetic basis.
"It would be interesting to know whether there was a correlation between women who suffer the worst symptoms and what their partners experience."
She added: "The symptoms, which often happen early in pregnancy, may be a sign of impending anxiety - the beginning of a pregnancy is an uncertain time."