The one I remember most clearly was that awful hurricane in October 1987 - there was a huge increase in births the following July

Melanie Every Midwife

But she said it meant midwifery and obstetric services could plan for a peak in services nine months after significant events.

One possible key time next year, she suggested, would be the Queen's Golden Jubilee.

"It would be interesting to see if there is a birth increase nine months later," said Mrs Every.

But she said an expected millennium baby boom did not materialise.

The pattern of seasonal births in the England and Wales figures, covering 1986 to 1996, is consistent.

Daily births

The National Statistics figures also showed there was a daily variation, something which has been seen since the 1970s, with more children born on weekdays compared to weekends and bank holidays.

That variation is likely to be connected to hospital workforce patterns rather than conceptions.

Mrs Every said the patterns in daily births were likely to continue, as procedures such as elective caesareans were not wanted at weekends.

She said: "There doesn't seem, as far as we can tell, any wish coming from the women themselves that they would rather these things were practised at the weekend."

Stillbirths tend to happen more on Saturdays, and neonatal death rates tend to be peak on Sundays.

Stillbirths and neonatal death rates were, in general, higher in the winter months.

There has been a decline in the number of stillbirths, with the steepest fall between 1979 and 1983.

The number of early infant deaths also fell from the mid-1980s to mid-1990s.

But it was higher for babies born in December and January and for those born in August, compared to the months before and after.

The report suggests this may be because August is the month when new junior staff take up their posts who may be "less well supervised" and that locum staff may be employed more to cover holidays, something which it says requires further investigation.

The report stated that: "There was a 'clear seasonal pattern' in the number of daily live births throughout the entire period, with lower numbers of births in the winter than the summer months.

"In each year, the lowest number of births occurred either on Christmas Day or on Boxing Day, usually the latter."

Numbers also peaked in September, but the maximum number of live births occurred between May and August.

The difference in daily birth patterns, the report says, is probably explained by obstetric practice. There are fewer elective caesareans and induced labours at weekend.