When I started work as a GP 15 years ago, I was given the job of immunising the babies. I hated doing it. I didn't have any kids of my own then, had no idea which way up to hold a baby and didn't enjoy hurting them. I remember parents asking whether their baby would get a fever and what side effects to look out for. But I have no memory of the hostile and suspicious interrogation that many doctors and nurses face now from anxious parents.

It used to be the case that a responsible parent presented their child for routine checkups and jabs without a murmur. My mother says that she and her friends didn't consider not immunising their babies in the 60s. Brought up in the bright new light of the nascent NHS, they had a trust in the state-provided health service that included the immunisation programme.

The first cracks in public confidence became noticeable in the 1970s. The whooping cough (pertussis) vaccine was known to occasionally cause neurological damage. This risk was known to be much smaller than the risks of whooping cough itself. But some cases of vaccine-induced damage hit the headlines and, since then, most of the media stories about vaccines have been negative.

Politicians have waded into the public debate. And when a politician smiles and says all is well, the public runs a mile. John Selwyn Gummer famously made his daughter eat a hamburger in front of media cameras to demonstrate the safety of meat at the height of the public's concern about reports linking the incurable disease of CJD to contaminated meat. Were we convinced? I don't think so. When Tony Blair interrupts his holiday to reassure us that the new five-in-one vaccine is safe, most of us snort with derision - especially when he never quite came clean about whether or not baby Leo had the MMR vaccine.

And although doctors still command more trust than politicians, we are more mistrustful of health programmes than ever before. No wonder public confidence has hit rock bottom. Scarcely a day goes by without another health "scandal" about babies' organs or misdiagnosis of abuse. These are the stories we read before taking our babies along to the clinic to get a jab. Is it any wonder we offer up their chubby thighs with such trepidation?

So it's no longer enough that jabs must be safe because doctors, nurses or health visitors say so. Babies are only two months old when they get their first jab. Experts say their immune systems can handle it and that leaving them unimmunised makes them susceptible to the diseases. But my first child was only 4lbs when she was born and still looked like a scrawny little chicken at two months. Instinctively, it felt very small to be exposing her to five different vaccines.

I did immunise all three of my children and would do so again. But what I needed then, and would want now, is time to discuss my concerns with a health professional who has no axe to grind. In many countries, childhood immunisation is compulsory; school entry is dependent on it. In the UK, we have a facade of parental choice but in reality, feel pressurised by health professionals. Because it's not compulsory, we feel responsible for making the right decision. Making that decision is difficult because no health intervention comes with a cast-iron guarantee that it is free of side effects.

There have been far too many changes to the immunisation programme over the past few years. Each change is supposed to be better and safer. So how does that make us feel about what we gave our older children? Take the new five-in-one vaccine coming out next month. It has, we are told, two main advantages. The polio vaccine will now be an inactive form of the virus rather than active and will be part of the jab rather than given orally. This is safer because the active form can apparently cause a mild form of polio, whereas the new type can't. Are we supposed to be reassured about that? Who knew that the old type could cause polio anyway? And the second advantage is that the new jab doesn't have any mercury- containing preservative, thiomersal, unlike the current one. The Department of Health says that's a good thing because the WHO has recommended removing thiomersal, but also says that we are not to worry about mercury because it is harmless. Confused? You should be.

All the same, we should not feel cowed by medical professionals or panicked by the media, but try to keep calm, ask the right questions and believe that doctors and parents are on the same side, with children's interests at heart.