"I didn't have multiple sclerosis then," I replied.
At times like that I am struck by a very sad thought: my own child has no idea of the person I used to be. No amount of telling him about being captain of the rounders team, hitch-hiking holidays in Europe or disco- dancing till dawn tallies with the mother he now knows: someone with the leg-power of a lame tortoise and the energy of a radio with run-down batteries.
It was a long time before I actually told Pascal I had MS. Why scare him, while I was still able to get around? He would only fret for my future and his. Like many people with MS, I decided my best tactic was to carry on as if nothing had happened. Not exactly denial, but not far from it.
But something clearly had happened, and he knew it. As a toddler, he probably didn't wonder why it was never me who raced after him as he scampered towards busy roads. But as a young child he did start to whine about why I never did anything fun with him: fly kites on the heath, play ball on the beach, or walk along wind-swept coastal paths. I hired another pair of legs, in the form of an au pair, to do those things for me.
He pleaded with me to go with him, but I always said I couldn't. "There's something wrong with my legs," I used to tell him. So I stayed behind, sitting somewhere on my own while he went off with other people, exploring rugged Brittany beaches, climbing scenic hills, walking across the heath or cycling along country lanes. When he came back it was always the same: "Mum, I wish you could have been there."
One day, as he set off for a cycle ride with the au pair, he asked, a touch sarcastically, "Mum, could you ever ride a bike?"
"Yes, when I was a child," I replied.
"But they say no one ever forgets how to ride a bike. So how come you can't ride one now?"
How come I can't run now? Ski now? Dance now? Work full-time now? How come I can't even walk properly now? The questions were growing by the year and it was time to tell him. The tactic of not telling anyone I had MS had many pitfalls. Other mothers tut-tutted when I didn't join in the rota of walking the local children home from school ("Your son isn't getting enough exercise!" warned one); the mothers' race on sports day made me panic in case I got roped in; and at the school barn dance everyone was gaily skipping up and down the hall, except me. I must have looked like a grade-one spoilsport.
In the end, the deed of telling was all but done for me. Pascal's best friend at school had an uncle with advanced MS, even though he was only in his mid-thirties. One weekend, when Pascal was visiting this friend, I knew the uncle would be there. "You'll meet Uncle Paul," I told Pascal. "He's got the same illness as me, but worse ... It's called multiple sclerosis."
Pascal was deeply affected by what he saw. Uncle Paul had been slumped in a wheelchair, badly slurred his speech and could barely swallow. Apparently, they had cracked jokes and watched TV together. "Paul hasn't lost his sense of humour at all," was Pascal's main comment. "Even though you can hardly understand a word he says."
Thank goodness Pascal was able to see beyond the very visible disability to the personality beneath. Perhaps my own MS, and Uncle Paul's, would make him more sensitive - if more scared.
Indeed, many other mothers with MS to whom I talked for my book thought their condition had made their children more caring and considerate, with a greater awareness of disability. Others had the normal kind of offspring who expect you to pack their sports bag for them even though you can hardly haul yourself upstairs to fetch the football boots. Most striking of all, nearly all the mothers I spoke to thought the joys of having a child far outweighed the disadvantages of being a mother with MS. I count myself among them.
But that joy and happiness comes by putting their own health at risk. In the six months after having a baby, a woman with the disorder runs a threefold higher chance of suffering a relapse and up to 75 per cent do (although this usually makes no difference to their disability in the long term). Small wonder that many women with MS choose to forego motherhood.
Others are prepared to jeopardise their own health in order to have the child they long for. "After my first son was born, I did have a very bad attack and was iller than I'd ever been," says Liz Brice, from Leeds, who has two children. "My mobility was hopeless, my manual dexterity wasn't very good, and I had to crawl round the house. But I was deliriously happy. I was blissful. I was completely in love with my baby.
"I didn't care that I couldn't walk, didn't care that I couldn't move properly, I was just so utterly delighted to have a baby. For me, having a relapse was as nothing compared to the joy the children have given me. It's the best thing I've ever done."
One woman I met was knocked sideways after childbirth. Gill Heath, a farmer's wife from Berkshire, is one of them. Before she had a child 10 years ago, she was energetic and sporty. Then she had a baby.
"Five weeks after my son was born my legs said, 'We don't want to know.' It was goodbye life really. I couldn't even get out of bed one morning. I didn't believe it. I love my son John very much, but if I'd known this was going to happen to me, I wouldn't have had him."
I was one of the lucky ones. At the age of 38, I had a quick and easy natural birth at home and suffered nothing more than the opprobrium of the medical profession who would rather I'd been in hospital strapped to bleeping machines being drip-fed drugs.
Twenty-four years ago, when I was diagnosed with MS at the age of 26, I was offered a sterilisation on the assumption that anyone with MS couldn't cope with motherhood. Outraged, I refused. With this disability, so much is taken away; I wasn't going to have motherhood taken away too. If doctors had had their way, Pascal would never have been born. Yet now he is my whole life.
Thankfully, times have changed. These days, doctors don't frown as much as they used to when a woman with MS wants a baby; some are even encouraging. But there are others who still hark back to the old attitudes that women with MS should never have babies. I wrote the book not just to set the record straight on the medical facts, but to put together the experiences of many mothers with MS. The conclusion is overwhelmingly positive.
"Mum, I wish you could have been there", has been the main refrain of my years as a mother. But then I try to reassure myself with the thought that the mum who Pascal will never see lacing up climbing boots, slaloming down a ski slope or riding a bike is the only mum he has ever known and loved. And maybe he wouldn't want me any other way.
When Pascal began to play "Rock Around the Clock" on his keyboard last week he seemed genuinely dismayed when I got up out of my seat a little more energetically than usual, tapping my toes as I did so. "Mum!" he said, embarrassed at the very thought, "You're not going to jive are you?"n
'Multiple Sclerosis, Pregnancy and Parenthood' by Judy Graham is available from the Multiple Sclerosis Resource Centre, price pounds 7.75 inc p&p. Tel: 01279-817101.Reuse content