Just when you think you've got toilet-training sorted, your child reverts to wetting herself. What can you do? Raisingkids.co.uk's parenting expert, Dr Pat Spungin, advises.

Raisingkids member's problem
My 3 yr-old has been toilet trained for a year now, but during the past few months she's reverted back to wetting herself. There's been no change of circumstances in the family - no new baby etc. - it just seems to me like she can't be bothered to go to the toilet any more. What do you think the problem is and what can I do? It's getting me down as it's difficult taking her to my friend's houses and even going out in general, as I'm worried how many times I'll have to change her. I don't want to revert back to nappies. Can you please help?

Dr Spungin's advice
I'd consider the possible explanations for your daughter's regression, starting with medical causes:

Maybe she has a urinary infection - it's unusual in young children but possible. Does she appear to have pain when she pees? Is her urine a different colour, or does it have an odour? Does she pee more often than she used to and/or have a sudden and urgent need to pee? If so, take her to your GP.

Sometime children become afraid of using the toilet. She may fear something may be in the WC pan or behind the lavatory. If she's using the toilet for bowel movements, then this is unlikely to be the cause.

Is she too busy playing to be bothered to go ? If so, a regular reminder would help.

Is it a battle of wills between you? Stay calm and matter of fact. Behave as if it was not very important to you. In this matter, she holds most of the aces.

Have you asked her why she wets herself? What does she say? What can you do? Remind her that big girls pee in the toilet. Tell her that mummy doesn't like to have to keep changing her panties. Ask her how you and she can stop this happening.

When she wets herself, ask her to go and change. Don't do it yourself. Offer her the choice of back into nappies or using the loo. (I know you don' t want to do this, but the prospect of going back into nappies 'like a baby' may be enough to encourage her and, when you go out, at least you can relax.) When she is clean and dry, or asks to use the toilet, encourage her but don' t overdo the praise. If she wets herself, be calm and matter of facts. See our Parenting Skills section for more pointers on how to reach an understanding with your child.

• More Answers From Dr Spungin
• More Potty Training Tips