The results of a new study by the World Health Organisation dangle intriguing question marks over one of the foundations of antenatal care: the frequency with which pregnant women should attend clinic.

For most of the past halfcentury, the recommendation has been for monthly visits until week 30, fortnightly until week 36, and weekly thereafter.

A drop in this frequency would release resources for other things;

and such a reduction is precisely what the WHO report has found to be feasible and safe.

In a large and carefully planned study (Lancet, 357: 1551, 64) carried out in Argentina, Cuba, Saudi Arabia and Thailand WHO researchers compared a group of women receiving conventional antenatal care with a similar group on a new regime. The two care models differed in various respects, but frequency of visits really set them apart.

In the new model, women made their first visit before 12 weeks, and thereafter at 26, 32 and 38 weeks: four visits in total.

The main finding of the trial can be summarised in a sentence:

'Provision of routine antenatal care by the new model seems not to affect maternal and perinatal outcomes. '

This study, together with a systematic review of other randomised controlled trials of antenatal care reported in the same issue of the Lancet (357:

1565-1570), resonate belatedly with a comment made 30 years ago by Archie Cochrane. 'By some curious co-incidence, ' he said, 'antenatal care has escaped the critical assessment to which most screening procedures have been subjected. '

If and when it is judged acceptable to recommend fewer antenatal visits, one obstacle may well be women themselves.

After decades of having been told how important these visits are, they may be inclined to rebel when the educational machine suddenly changes gear and starts telling them that fewer visits will do the job just as well.