In my book contraception is a dirty word: the Pill can be dangerous, condoms can split, the Coil give you a nasty infection - and a friend of mine had to go back to have it trimmed down because it was stabbing her partner. Gruesome. If you use the Cap you practically have to take a flight bag with you to carry all the bits. And the Sponge and the Femidom just conjure up images of school pudding and boil-in-the-bag.

So it was with some interest that I saw an ad for Persona - a "system" that allows you to "make love" without using any contraceptives. Sure, I thought. The catch is?

Well, it wasn't a steal - pounds 49.95 for the "monitor" and pounds 9.95 for a box of eight "test sticks". Basically the deal is that you press a button on the monitor when your period starts, and do 16 urine samples the first month and eight every month thereafter. By measuring your hormone levels it tells you when to Do It and when Not To. Simple. Well, sort of ...

The 62-page booklet gives supposedly clear instructions on how to log on to your pocket-sized system. Unfortunately there was no Persona For Dummies handbook. On my "M" day (day 1) I was thrown into a panic over when exactly I should press my M as this would establish my "testing window". There is, thank God, a helpline - sorry, "careline", which after leaving me on hold for 20 minutes, informed me that around 8am would be a good time for me to press.

After this it is relatively plain sailing. Waking up to your monitor in the morning is rather like waking up at the traffic lights: Green = Go for it! Red = Not Tonight! And Amber = A sample please! Amber is my least favourite light. This means using a test stick (or a pee stick, as my husband affectionately calls it) and trying to pee on it for three seconds during your testing window, then inserting it in the monitor's "test stick slot". Five minutes later a verdict of Green or Red will be reached. As an added bonus a cute little 0 with a dot in the centre flashes when you are ovulating.

I have to say, apart from the peeing bit, so far so good. The system is allegedly "as reliable as a condom", but I'm not without my fears. Every Tuesday I have to hide it from the cleaner in case she scrubs it with something abrasive and inadvertently causes us to become parents.

Persona is available exclusively from Boots. For more details call Careline (0800 994455).