NHS trusts have accepted that last week's Healthcare Commission report into maternity services should serve as a 'wake-up call' but have complained that the review's methodology may have treated them unfairly.

Trusts' concerns around the methodology led to a last minute concession by the commission to change the labels used in its overall assessment from its usual "poor/excellent" to "least well performing/best performing". Low scoring trusts had lobbied the commission saying that it wasn't fair to be labelled "poor", since the review was comparative.

A spokesperson for the commission said: "We were persuaded by what they said and changed them. We felt it was terribly important not only to listen to what they said but also to be flexible enough to make adjustments.

However, the spokesperson added: "It is important to understand that those organisations in the lowest category performed relatively poorly on a range of indicators. We understand that some trusts will find this an uncomfortable message, but there have been real concerns about maternity services and the issues need to be met head on."

HSJ has been told that trusts were asked to complete a mixture of "mandatory" and "non-mandatory" questions. Those that did not answer the non-mandatory ones found they were penalised a point.

Healthcare Commission chief executive Anna Walker stressed: "Being put in the least well performing category does not mean that a service is unsafe. If we believed any unit to be unsafe, we would take immediate action to ensure patients were protected."

Maternity units in London performed particularly badly in the review. Of the 31 trusts in the bottom category, 19 were in the capital - representing more than two thirds of the 27 London trusts that offer maternity services.

Royal College of Midwives deputy general secretary Louise Silverton told HSJ that the poor performance in London may have been partly due to the mobile nature of the population.

Part of the review was based on a survey of patient experiences, but a significant number of women in London may attend antenatal sessions at one hospital yet give birth at another, making it unclear which maternity units they were scoring.

Ms Silverton said: "The quality of some of the data is a bit iffy."

She went on to say: "For those [trusts] that performed least well, this will be a wake-up call for their board about the resources they are putting into their maternity services."

2006-07 saw a real-terms cut of£55m in maternity services funding, despite the fact that the birth rate rose by 5 per cent in some areas and 12 per cent nationally from 2001-06, Ms Silverton said.

An Imperial College Healthcare trust spokesperson agreed the report was 'a wake-up call', but added that as it cared for some of the most complex cases in the UK, it had been "a pity that the Healthcare Commission's assessment was unable to take into account our perinatal mortality rates, which are better than in the [rest of the] UK and [the] US".

For more analysis, see HSJ's feature on the Born in Bradford project