Self-injectable contraceptives, which are being trialled in Uganda and Senegal, could revolutionise women's lives in rural Africa and dramatically cut maternal and newborn deaths, health experts said on Tuesday.
The disposable $1 device consists of a small needle connected to a plastic bubble containing the contraceptive Depo-Provera which can be squeezed to inject a dose that lasts three months.
Self-injectables could have a major impact on the lives of women who cannot access clinics or who face opposition to contraceptive use from their partners, said the global health organisation PATH which has designed the device called Sayana Press.
"This is a life-saver. This is a game-changer for family planning," PATH's Emmanuel Mugisha told the Thomson Reuters Foundation at Women Deliver, the world's biggest women's health and rights conference in a decade.
Unwanted pregnancies also cut short girls' education and stop them reaching their potential.
Mugisha, PATH's Uganda director, said women in rural areas could spend an entire day trekking to a clinic and queuing for contraceptives only to discover they were out of stock.
"In Africa, one of the hindrances with family planning is access. The second hindrance is us men," he said.
"Most men don't want family planning. Some want more children, but others think it interferes with their sex life.
"With Sayana Press a woman has the freedom to decide when she wants children and when she doesn't, and the man will have no control; the man will not know, which is very good."
Mugisha said self-injectable contraceptives would also reduce the high numbers of women dying during botched abortions in Uganda.
Some 225 million women in developing countries have an unmet need for family planning, according to U.N. data.
If this need were met, unintended pregnancies would fall by 70 percent, unsafe abortions by 74 percent, maternal deaths by 25 percent and newborn deaths by 18 percent.
Trials with Sayana Press, which is manufactured by Pfizer, are being carried out to ensure women can remember to take it, administer it correctly and dispose of the device safely so that it does not get picked up by children.
Nomi Fuchs-Montgomery, an expert on contraceptive technology at the Bill and Melinda Gates Foundation which is helping support the trials, said early indications were very positive.
"We see so much promise with this," she added. "This is really the future."
Fuchs-Montgomery said increasing the availability of contraception had a major role to play in meeting many of the Sustainable Developing Goals - the U.N. goals agreed last year for ending inequality and extreme poverty.
Access to contraception allows women to complete their education, follow careers and participate economically which has "an incredible knock-on effect" on their wider communities and national development, she added.
PATH is also conducting trials in Burkina Faso and Niger where community health workers are using the device to deliver contraceptives to women.
Some 5,500 delegates from over 160 countries - including policy makers, business leaders, health workers, activists and celebrities - are attending the Women Deliver conference which ends on Thursday.