The government of El Salvador took a truly extraordinary step in an attempt to control the rapidly spreading Zika virus last week by asking its citizens to avoid getting pregnant from now until 2018. Yes, you read that right.

The mosquito-borne virus is suspected to cause a condition called microcephaly, in which fetal brain development is stunted when a pregnant woman becomes infected. While other states in Latin America have warned women of the dangers of getting pregnant while the virus is uncontrolled, El Salvador has taken the strongest stance against pregnancy.

From a demographic perspective, it’s a fascinating experiment – how much can the government really control fertility, and can they do so without resorting to coercion? If successful, the results could be significant in a region that already has sub-replacement fertility and in some places lacks strong health services.

An Extraordinary Step

According to the World Health Organization, many regions across the world have reported transmission of Zika, including 20 countries in Latin America. There is currently no vaccine or treatment and an assessment in the Journal of the American Medical Association reports a solution is three to 10 years away, at best. Brazil, with over 207 million people, has reported 3,893 cases since October – a huge spike – but El Salvador, with a population over just over 6 million, has reported over 5,000 cases since January 2015.

If El Salvador and other countries’ warnings about pregnancy and Zika have the intended effect, women who would otherwise choose to start families will at the most delay their plans. Such delays would only cause a temporary drop in birth rates (although certainly not to zero) followed by a potential spike once the virus is under control. These patterns are not unusual, as women often time childbearing with larger economic and political climates. Birth rates frequently decline during economic depressions and wars, for example.

A vaccine or treatment is three to 10 years away

El Salvador’s total fertility rate – the average number of children born to a woman in her lifetime – has dropped from over five children per woman in 1980 to 1.97 today, and the UN projects further declines. Coercive measures are thus unnecessary and, in this predominantly Catholic country, also unlikely. Although news outlets are reporting the government’s implicit endorsement of birth control as controversial, family planning is already a widespread practice in El Salvador and most countries of the region, which are rapidly aging. The median age of El Salvador’s population is on track to increase from 26.7 to 35.5 over the next 20 years.

Brazil, Chile, and Cuba also have sub-replacement fertility rates, reflecting existing family planning infrastructure, while Bolivia, Guatemala, and Haiti – three countries with Zika virus transmission detected – have relatively high fertility. Women in the latter countries could be unable to control the timing of their pregnancies because of a lack of access to or knowledge of family planning methods and thus an outbreak there could have more devastating long-term effects.

In Central America, the current contraceptive prevalence rate is 71 percent on average, but ranges from 57 percent of women in Guatemala using any method of contraception to 80 percent in Nicaragua. In South America, the average is 75 percent, with a range of 45 percent in Guatemala to 70 percent in Brazil. In El Salvador, 71 percent of women use contraception and 12 percent report unmet need for family planning.

If women choose not to or are unable to heed the warnings about pregnancy, several outcomes are possible: more babies with microcephaly may be born; more women may seek abortions for fetuses with the condition (and in countries like El Salvador where abortion is illegal, these could be dangerous); or little will change, demographically.

Beyond Demographics

If more babies with microcephaly are born, there will be multiple economic consequences – in addition, of course, to the individual and family strains of caring for a child with special needs. The gulf in levels of development among states in the region may widen as a result of uneven family planning infrastructure.

There will be economic costs associated with increased contraception, family planning programs, education, and care of children born with complications. The disability rate of young children in El Salvador will rise as the virus further establishes itself, meaning that there will be a greater proportion of the population unable to work in the future. Productivity among mothers of affected children will also drop as they leave the workforce to care for their children. Colombia expects 700,000 infections as a result of the outbreak, which will affect economic productivity in general.

Effectively combating the virus requires significant government resources. In Haiti, 48 percent of the population reports unmet need for family planning, and the government does not currently have the capacity to expand infrastructure to meet demand. The Brazilian government has mobilized the military to eradicate mosquitos and announced on Tuesday that it would direct 220,000 soldiers to hand out educational leaflets.

Regional gulfs in development may widen

Some in El Salvador’s administration may hope to see a fall in gang violence and other economic benefits from a smaller youth population, but such demographic changes would only start to manifest a decade from now at the very earliest. In the shorter term, emigrants could return home to fill jobs vacated by people affected by the illness. Twenty percent of the population lives abroad and unemployment is a respectable seven percent. The population growth rate could begin to slow as well. The country is densely populated, and the vice health minister has said publicly that a fall in birth rates would not be a bad thing.

Lastly, abortion under all circumstances is illegal in El Salvador (and three other countries in the region), but concerns over the disease could potentially reshape the country’s social views, sparking debate about reforming abortion laws and the church’s stance on family planning.

Since most women in the region will probably be unwilling or unable to postpone pregnancy for two years we should not overstate the demographic implications of El Salvador’s request, but the fact that the government was willing to make such a request is the more interesting takeaway. Governments often have the desire to raise or lower their population’s fertility because they see the connections between total size or age structure on the one hand, and economic growth or military power on the other. Absent coercion – a gross violation of human rights – providing adequate health services and economic incentives has proven key to meeting these goals. If El Salvador marshals the required resources then the Zika virus might have one positive effect amid its tragic consequences: improved access to health care and contraception.