Scientists are dumb. Here is why:

Human gestation, they tell us, lasts 40 weeks.

During the first two of those weeks, there is no pregnancy, as conception has not yet occurred.

So pregnancy really only lasts 38 weeks.

But scientists like nice round numbers so they say 40 instead of 38.

You will remember that, back in September 1999, NASA's Mars Climate Orbiter fell down and went boom because of precisely the same sort of mathematical stubbornness.

Scientists say that a baby is due to be born on the first day after the end of the 40th (38th) week of pregnancy.

Scientists also say that 70 per cent of women having their fist children deliver in the week following the due date.

Therefore, the official, scientific definition of "due date" is as follows:

Date on which the probablility of the baby's birth is vastly less than 30 per cent.

Moving the date into the 41st (39th) week would correct the problem, but scientists refuse.

Therefore they are stupid.

Safety Carrot is still very nice, however.