All over the developing world, private benefactors are funding libraries, fighting malaria and working to eradicate polio. Bill and Melinda Gates are the modern equivalent of Victorian philanthropists, providing grants worth $3bn in 2009 alone. They're funding agricultural projects, providing resources to help women farmers, and their latest initiative is about safe contraception. Melinda Gates will be in London in 10 days' time to host a family planning summit with Andrew Mitchell, Secretary of State for International Development.

The summit's ambitions are laudable. Around 215 million women in developing countries aren't able to make choices about when to have children, and the aim is to deliver safe contraception to 120 million of them by 2020. DfID is expecting "global leaders" to attend the event, although it hasn't released names as yet. But there is a problem: experts point out that lack of contraception is just one factor behind the many thousands of unwanted pregnancies each year. This week, ActionAid will publish a report ahead of the summit, highlighting the role of domestic violence in preventing access to contraception.

The charity's report includes an interview with Hadia Ali Makame, a 46-year-old mother of eight from Zanzibar, whose husband ignored her pleas. "I refused to have sex and he slept with me. I got pregnant, yet my child was only eight months old. He … forced me." Last week, a DfID spokesman assured me that education would be an important part of the summit, including challenging male attitudes that demand repeated pregnancies as a demonstration of virility. But he confirmed that abortion isn't on the agenda.

It is an astonishing omission. An estimated 68,000 women die each year in backstreet abortions, according to the World Health Organisation, and millions more suffer permanent damage. Family planning experts know that husbands force wives into unprotected sex, girls get pregnant as a result of rape, and condoms break. I am sure the people organising the DfID/Gates summit know it too, so why are they refusing to discuss abortion?

This, I'm afraid, is where the link between governments and private philanthropy becomes problematic. Melinda Gates has said she doesn't want the foundation to be drawn into the controversy. "We're not talking about abortion," she said in April, pre-empting NGOs who believe it makes no sense to exclude it from a major initiative on family planning.

Gates says she wrestled with her conscience before publicly opposing the Vatican's teaching on contraception, and it may be that she regards abortion as a step too far. But it's hard to see why a private citizen should be able to dictate government policy. Ministers will let down women in developing countries if they exclude it from the summit agenda of the landmark London summit.

www.politicalblonde.com; twitter.com/@polblonde