Contraceptive injections moderately increase a woman’s risk of becoming infected with HIV, a large scientific analysis has found.
The research in a leading medical journal will further fuel a controversy that has been raging for more than two decades. The implications of a possible link between hormonal injections and the virus alarm both HIV and birth control campaigners. Some countries in sub-Saharan Africa, where HIV rates are high, have considered withdrawing the contraceptive injections entirely from family planning clinics. About 41 million women use the jabs, in many cases because it allows them to control their fertility without their husband’s knowledge.
The analysis, in the journal Lancet Infectious Diseases, finds that in the pooled results of 12 observational trials, there is a 40% increase in the risk of HIV for women using the birth control jab compared with other hormonal methods such as the pill.
The US authors, from the University of California at Berkeley, said this was a moderate increase in risk. What it means for each individual woman will depend on her risk of HIV infection to begin with. For most women, the risk of an unwanted pregnancy and possibly death – maternal mortality rates are high in sub-Saharan Africa – may outweigh the increased risk of HIV.
For groups of women such as sex workers who have a high risk of HIV infection, the implications may be more alarming. However, the authors said there were only two studies that focus on this specific group and so the results were not conclusive.
The lead author of the research said the evidence was not strong enough to justify the complete withdrawal of depot medroxyprogesterone acetate (DMPA), more commonly called Depo-Provera, from women in the general population.
“Banning DMPA would leave many women without immediate access to alternative, effective contraceptive options. This is likely to lead to more unintended pregnancies, and because childbirth remains life-threatening in many developing countries, could increase overall deaths among women,” said epidemiologist Lauren Ralph.
But, she added: “Further evidence regarding the magnitude and mechanisms of the DMPA and HIV link among high-risk women, such as commercial sex workers and women in serodiscordant partnerships (where one partner is HIV-positive and the other is not), is urgently needed.”
The possible rise in HIV infections among women using the contraceptive jab was first noted in 1991. The debate over it has become “increasingly narrow and fierce”, said Christopher Colvin from the University of Cape Town in South Africa and Abigail Harrison from Brown University School of Public Health in the US in a comment in the journal.
“Like many scientific controversies, views have become hardened, personal, financial, or political agendas have been suggested, and there has even been intrigue in the form of leaked copies of articles under peer review,” said the commentary.
“Both sides have raised important, compelling arguments, but their partisan character can weaken the quality of the debates and restrict the view of the complex relation between evidence, policy, and practice.”
The debate is currently focused on whether there should be a large randomised controlled trial. This would need to compare HIV infections of women using the birth control jab probably with another group using the pill. Some would say that in the light of current evidence that would be unethical. Others warn a trial may not be decisive.
Colvin said that although trials can sometimes be the best option, they have their limitations.
“I do think that the debate over the trial, in both public and scientific circles, tends towards framing a trial as the way to ‘get the answer’ … which makes me nervous,” he told the Guardian.
The World Health Organisation advises that women at high risk of HIV should be told that the injectables “may or may not increase their risk of HIV acquisition”. Couples should be informed and given access to other methods, including male and female condoms.