However, the euphoria doesn't usually last long and at least one child was moved to write in her diary -- ``How much longer before I can give the thing back?'' Another child was reported to be so desperate to return hers that she threw the doll at her teacher.

No wonder. This is no ordinary doll. Behind the sweet exterior lurks an effective tool in the battle against teenage pregnancy in the country. The doll, christened ``Baby think it over'', is in effect a type of robot and is being employed to show young kids exactly what it would be like to have to care for a real baby.

The computerised plastic toy is programmed to start crying every two hours, interrupting homework or a telephone call to a friend, in the cinema or even in the middle of the night.``Mum'' or ``Dad'' then has to drop everything else and press an electronic switch on the doll's body for up to half an hour to quieten their charge.

The key needed for this operation is fixed to the teenager's wrist for the test period, usually lasting several days. The whole exercise is to simulate how much time would actually be required to feed, change and carry about a real child.

``This makes the responsibility much more realistic than a film or a book,'' says Carol Lambert, a spokeswoman for the manufacturers of the doll in Eau Claire, Wisconsin.

Sachas Mays, for example, was woken up by ``baby'' four times in one night. ``After the first day, I was ready to give it back,'' admits the teenager. ``It is a lot of responsibility and prevents you from doing other things you want to do.''

Along with Sachas, almost a million other teenagers in the US have been spending many restless days and sleepless nights having to look after their dolls, according to the manufacturers' estimates.

The doll,which was invented some five years ago by a Californian aircraft engineer, has since won several awards. Each doll costs between 250 and 290 dollars and come politically correct, in differing skin colours. There is even a ``crack doll'' on offer, which displays the effects of drug withdrawal, crying for care almost incessantly.

In no other industrialised nation do more teenagers suffer unwanted pregnancies than in the US. There are almost a million every year, according to the national campaign for the prevention of teenage pregnancies. Although numbers have been dropping sharply, an unplanned family still means leaving school prematurely, bleak job prospects and subsequent social problems.

Although no comprehensive study results are available, teachers and staff at schools are reporting at times an astonishing change of attitude.

``Before the courses with the dolls, almost half the kids said they felt mature enough for parenthood. Afterwards: none,'' says Aimee Bollinger Smith, head of a socialprogramme being carried out in Baltimore county, Maryland. At the same time, according to Bollinger Smith, there has been a dramatic increase in the willingness to use contraceptives.

Above all it is schools and social institutions who greatly value the three kilo, lifelike doll. Previously the care needed by babies was demonstrated in schools by letting the teenagers carry about self-made baby dummies, made from little sacks filled with flour and raw eggs.

The plastic dolls, in comparison, not only possess impressive lung power, but also do not let themselves be ignored. A built-in microchip registers if the doll is being neglected or treated roughly, which in turn will mean a visit by the teenager to the teacher to explain, or a drop in grades, or what for some is the worst of all, being kept in to look after the doll.