It is one of the world's greatest hidden epidemics, but the search for a solution is hopelessly underfunded. On average, every minute of every day a woman somewhere dies in childbirth or pregnancy, the overwhelming majority in developing countries.

Osman, a six month old baby whose mother died during childbirth in Sierra Leone. (Photograph: David Levene) It is estimated that they number more than half a million every year, in what Norway's Prime Minister, Jens Stoltenberg, told the United Nations last week was 'the biggest expression of brutality to women I can imagine'.

One of the UN's eight Millennium Development Goals in 2000 was to reduce the ratio of maternal mortality - the number of mothers who die per 100,000 - recorded over the period 1990-2015 by three quarters. But as the 2015 target date gets ever closer, it has become clear that attempts to lower the death toll have failed.

Even as Sarah Brown, wife of the British Prime Minister, became a patron last week of the campaign to reduce deaths in childbirth, Margaret Chan, director-general of the World Health Organisation, was conceding how little had been achieved. 'Despite two decades of efforts,' she said, 'the world failed to make a dent.'

Chan was addressing a high-level UN taskforce, whose members - including Gordon Brown, the World Bank president Robert Zoellick and French Foreign Minister Bernard Kouchner - are calling for billions more dollars in aid: $2.4bn next year, rising to $7bn by 2015. 'We still have time, but just barely, to make up for this failure,' Chan added. 'The number of maternal deaths will not go down until more women have access to skilled attendants at birth and to emergency obstetric care.'

With almost 99 per cent of maternal deaths occurring in the developing world, the differences in risk for women in those countries, in comparison with Europeans, are staggering. One in every seven women in Niger will ultimately die of pregnancy-related causes, whereas in Sweden the lifetime risk is one in 17,400.

Sierra Leone remains a stark reminder of that contrast, suffering one of the highest maternal mortality rates in the world, with one in every eight women dying in childbirth, according to Unicef. The experience there mirrors that in most of sub-Saharan Africa, where the maternal death rate has remained almost unchanged since 2000.

Thousands of women die every year in childbirth in Sierra Leone, which is at the bottom of the UN's human development index and where life expectancy is 41. Although care is officially free for pregnant women and under-fives, the health service is failing miserably. Only 40 per cent of the population has access to healthcare.

For the million-strong population of the capital, Freetown, there are only 162 government health workers trained to deliver a baby. Countrywide, there is one doctor for every 33,000 people or more, compared with one to 600 in the UK. 'Women are dying unnecessarily in pregnancy and childbirth,' says Barbara Stocking, director of Oxfam, which is calling for universal access to healthcare and for donor aid to go straight to national health budgets. 'It destroys families - children are motherless; husbands without wives; parents lose a daughter; siblings lose a sister.'

The health of mothers is crucial for the survival of families and economies, and cuts to the heart of any society. Pregnant women in Sierra Leone need what pregnant women need everywhere: trained midwives and doctors, access to properly equipped hospitals and essential medicines.

Deaths relating to obstructed labour, eclampsia, severe bleeding, anaemia and infection are often avoidable through simple measures, such as provision of better prenatal care and primary health facilities with trained staff.

Official government policy is to provide free drugs, consultations and essential vaccinations for vulnerable groups, including children under five, children attending school and pregnant and breast-feeding women. Common drugs are also meant to be provided on an affordable basis to everyone.

However, this is far from the reality: a recent survey found 90 per cent of respondents were paying for drugs, 43 per cent for consultation fees and 21 per cent for basic vaccines. In the eastern region of the country, around 90 per cent of those surveyed were still paying for antenatal and under-fives' healthcare.

The White Ribbon Alliance for Safe Motherhood, led by Sarah Brown and supported by Naomi Campbell, Erin O'Connor and Claudia Schiffer, is campaigning to help these women, as are NGOs such as Oxfam.

What can be achieved in this area has been shown by the experience of Sri Lanka, a developing country that now has a trained midwife for every 1,800 people. While Sri Lanka now suffers a total of 190 maternal deaths per year, Niger, which has a smaller population, has 14,000 maternal deaths every year - and only one midwife for every 33,500 people.

Despite the urgent need to reduce the death rate of women in childbirth, Robert Zoellick delivered a note of caution over the UN's ability to raise the billions of dollars that are needed, saying that he was 'concerned' over the impact that the global financial meltdown might have on programmes such as the Millennium Development Goals.