I recently told my daughter that I have a baby in my tummy. She looked puzzled. The next day she woke up and announced: 'Mummy, I've got a baby in my foot.' You can't argue with that kind of logic, can you? In theory, it all makes perfect sense.

One thing I'm learning fast is that second pregnancies are full of new surprises and can totally differ from the first. One area that has totally taken me by surprise is the new travel advice given to pregnant mums.

Three and a half years ago as a travel writer pregnant with Hanna, I thought I was pretty up to date with the rules. First three months, do what you can within the limits of sickness and tiredness; for the middle three months you can travel further afield, but don't go too far off the beaten track and stay within access of medical help and in zones where you don't need jabs. For the last three months, stay at home (unless you find an airline that'll agree to carry you with permission from your doctor, or an insurance firm willing to give you travel insurance after the 28th week).

So when I found out I was pregnant this time, I wasn't too worried about a long-planned trip with my mum to see long-lost relatives in Queensland, Australia. I would be about five months into the pregnancy and, judging from the previous pregnancy, it would be a good time to go: after the sickness had stopped and before becoming elephantine. At the same stage in the previous pregnancy, I'd travelled to Jamaica and had a great time.

As the pregnancy progressed, I rang my midwife to double-check that the Australia trip would be okay.

Her response amounted to the following: 'What? Australia? Are you mad? Don't you realise that pregnant women are one of the most susceptible groups to deep-vein thrombosis? That is 24 hours of flying. I wouldn't recommend any pregnant woman to fly that distance.'

'But I went to Jamaica last time and I was OK...'

'Yes, but the Caribbean's a nine-hour flight away. Australia is another story. If it's just for a holiday and you could go some other time, leave it. The only time we'd condone a pregnant woman flying that far would be if there were a death in the family or something extremely important. Even then we'd give lots of advice, like walk around the plane as much as you can and drink gallons of water. It's very, very dangerous. I recommend you cancel your trip.'

We did.

It looks as if pregnant women are not the only ones worried about DVT. A new survey from Visa International last week found that holidaymakers are more put off flying long-haul by DVT than 11 September.

Considering that Australia is the second most popular long-haul destination among Brits, airlines are going to have to improve leg room substantially to keep families travelling there.

It's interesting how so much can change in the medical advice to travellers in three years.