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Thursday, 15 February, 2001, 02:47 GMT
Space age panty liners
Predicting when a woman could conceive may be easier with the panty liners
Predicting when a woman could conceive may be easier with the panty liners
Women may one day be able to predict when they are going to have their period and when they will ovulate with innovative "smart" panty liners.

Those embarrassing days when a period starts unexpectedly, and the difficulty of trying to predict ovulation, could be things of the past.

Scientists at Procter and Gamble, makers of Always and Tampax, have filed patents for panty liners which could be impregnated with chemicals to help women understand their menstrual cycle.

The patents cover panty liners that could change colour to indicate when they are going to ovulate, and ones that could spot if period is about to start.

Patents have been lodged for liners which could test for pregnancy, and ones which may be able to tell a woman if she has a bacterial, fungal or viral infection, such as thrush or chlamydia.

Tests by the company, detailed in the patents and highlighted in New Scientist, showed how panty liners impregnated with gun guaiac wood resin and carminic acid could indicate periods.

The resin turns blue when it comes into contact with tiny amounts of blood, and the acid turns red when it is acidic.

Both chemicals turn purple up to four hours ahead of menstruation.

Hormone detectors

The panty liner that could predict ovulation works by using a chemical that can identify key hormones.

The liner would have a plastic film coated in a substance called amorphous silicon.

The silicon changes thickness when levels in oestrogen, progesterone and follicle-stimulating hormones change.

The changes create a purple spot on a gold background.

In September last year, New Scientist revealed Canadian and South African scientists are also working on similar pads, but they may need to be tested in a laboratory.

But the idea is not new.

In the early 1990s, the German company Media-Pharma and US-based Kimberly-Clark were among those who filed patents for sanitary towels and nappies which would change colour depending on the amount of glucose and nitrates in blood and faeces to help detect certain conditions.

A spokeswoman for Procter and Gamble told BBC News Online: "Procter and Gamble is a company of innovation and it's not unusual for us to file patents that may lead to new products.

"We believe technology like this provides some interesting future possibilities for us."

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21 May 99 | Medical notes
Pre-Menstrual Syndrome
17 Nov 00 | Health
Fertile days 'hard to predict'
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