With no vaccine, no cure, and without even a reliable diagnosis, doctors are at a loss for how to protect their patients from the Zika virus. In the past year, the mosquito-borne disease has spread throughout Latin America, sparking panic because of a possible link to microcephaly—babies born with abnormally small brains. Without more information, medical advice so far has boiled down to this: Don’t get pregnant. So say official guidelines from Brazil, Colombia, and Honduras. El Salvador has gone so far as to recommend women do not get pregnant until 2018.

But most of these Latin American countries are also Catholic, so access to birth control is often poor and abortion is flat-out banned. “This kind of recommendation that women should avoid pregnancy is not realistic,” says Beatriz Galli, a Brazil-based policy advisor for the reproductive health organization Ipas. “How can they put all the burden of this situation on the women?”

In Brazil, where Zika has hit the hardest, birth control is available—though poor and rural women can still get left out. One report estimates that unplanned pregnancies make up over half of all births in the country. And abortion is illegal, except in cases of rape and certain medical conditions. A raft of impending legislation in Brazil’s conservative-held congress may make it harder to get abortions even in those exempted cases.

Now throw Zika into that. Scientists still haven't confirmed the link to microcephaly, but Brazilian researchers have confirmed the virus can jump through the placenta from mother to fetus. Circumstantially, the number of of microcephaly cases has gone up 20 fold since Zika first reached Brazil. In the face of fear and incomplete information, women will have to figure out how to protect themselves and their children.

Illegal Abortions

If a woman is already pregnant or accidentally becomes pregnant in Brazil, her choices are both legally restricted and medically confusing.

Illegal abortions already happen; 200,000 women in Brazil get hospitalized every year for complications from the procedure. Having one is punishable by up to three years in prison.

In 2012, a Brazilian supreme court decided that terminating a pregnancy would be legal when the fetus develops with no brain and has no chance for survival, a condition called anencephaly. Microcephaly, where the brain is too small, is more complicated: It can be fatal in some babies and result in permanent disabilities in others.

Zika makes the confusion even worse. The virus doesn’t make everyone ill, so not having any symptoms is no guarantee of safety. If a woman does get sick, the symptoms of Zika are not unique and diagnostic tests are not reliably available. Even diagnosis of microcephaly via ultrasound is tricky early in pregnancy. It can be hard to know how abnormal the size of an unborn fetus’ head is, says Kjersti Aagaard, an obstetrician at Baylor College of Medicine in Houston, because “those measures are what help us date a pregnancy.” The reasoning is circular: A fetus’s head may be too small for their age, but if you don’t know the age, you don’t have a reference point.

Galli says she suspects individual women infected with Zika may try petitioning judges to allow abortions. Brazilian judges have on rare occasions granted abortions to women whose fetuses were in danger of severe birth defects, and one judge has expressed sympathy for Zika-infected women carrying babies with microcephaly. But this last-ditch legal route is slow and accessible only to well-resourced women.

Rubella and Abortion in the US

In the 1960s, doctors in the US had in a similar dilemma. The virus rubella can cause blindness, deafness, and other birth defects. Like Zika, the symptoms of rubella in everyone but pregnant women were so mild that nobody paid much attention. Then a pandemic hit in the 1960s. Abortion was illegal at the time, but so-called therapeutic abortions—if doctors deemed them medically justified—were allowed. Few doctors actually performed them, though.

The media picked up on the plight of white, middle-class mothers seeking abortions after getting rubella. LIFE even ran a cover story. That narrative ran counter to the stereotype of abortion-seeking women as poor, unmarried, and somehow deviant. “To have middle-class white married women speak publicly about abortion made abortion respectable and decent,” says Leslie Reagan, a historian at the University of Illinois at Urbana–Champaign and author of Dangerous Pregnancies, a book about abortion and the rubella outbreak. The conversation around abortion shifted in the US, leading to state laws that decriminalized abortions and eventually Roe v. Wade.

With Zika in Brazil, Galli thinks opening the debate to medical justifications of abortion could help destigmatize the issue. But she’s not optimistic, given the anti-abortion legislation currently in congress. “We are facing a lot of threats,” she says. “We are fighting to try to secure what we have instead of trying to advance and expand legislation.” For now, pregnant women face a set of choices more constrained than ever.