Almost a year has passed since Brazilian health officials announced they had established a link between the mosquito-borne virus Zika and birth defects. Since the beginning of the outbreak of the Zika virus in 2015 in Brazil and other Latin American countries, researchers have raised increasing alarm over the disease’s link to birth defects. The most severe of these defects is microcephaly, a condition in which children are born with head circumferences well below normal, with effects ranging from mild developmental delay to devastating cognitive and neurological impairment. While the exact mechanism by which Zika causes microcephaly in infants in utero is not yet known, a growing body of evidence supports the link between the virus and the defect. According to a recent published review of evidence to date, “data from Brazil regarding the temporal and geographic association between Zika virus infection and the later appearance of infants with congenital microcephaly are compelling.” Given the severity of many microcephaly cases, governments and health organizations have raced to gather and distribute information that will help women facing the virus.
On Nov. 17, 2015, the Pan American Health Organization issued an alert warning of an “Increase of microcephaly in the northeast of Brazil,” and by Dec. 1 had announced a potential link between the rise in microcephaly cases and Zika. Subsequently, governments in many Latin American countries issued warnings to women to avoid pregnancy. The most extreme of these came in January, when El Salvador’s Deputy Health Minister warned all women of fertile age that they should “take steps to plan their pregnancies, and avoid getting pregnant between this year and next [2016 & 2017].” Colombia’s warning called for women to delay pregnancy only six to eight months, while Brazil and a handful of other countries did not specify a length of time.
At the same time, the World Health Organization and the Centers for Disease Control and Prevention advised pregnant women not to travel to areas with active Zika transmission. In response, tourism to Latin America has declined this year, with a sudden drop-off in some areas of the Caribbean that correlates closely with the CDC announcement. Some airlines have even offered reimbursements to pregnant women and couples traveling to affected areas.
But panic over Zika is motivating more than switches in vacation destinations. In the United States, fear of Zika-related microcephaly appears to be driving increased acceptance of late-term abortion. A recent poll from Harvard’s School of Public Health found that 59 percent Americans believe abortion should be permitted after 24 weeks if there is a “serious possibility of microcephaly” due to Zika, while only 23 percent feel that abortion should be permitted after 24 weeks in general cases.
The spread of Zika has also caused a sharp increase in abortion demand in many affected countries, according to a study published in July in the New England Journal of Medicine. The study conducted by five researchers looked at abortion requests submitted by Latin Americans from Jan. 1, 2010, to March 2, 2016, to the Dutch telemedicine NGO Women on Web, which provides medications via mail to induce abortion up to the ninth week of pregnancy in countries that restrict abortion. The researchers compared requests before and after the PAHO alert in November and divided countries into three groups: two groups with active Zika transmission that either did or did not issue a national pregnancy warning, and a third without Zika transmission. While abortion requests remained steady in countries without Zika pregnancy warnings, in all but one country that issued pregnancy warnings, abortion demand rose significantly. In Brazil and Ecuador, demand more than doubled, while other countries with pregnancy warnings saw increases between 35 and 94 percent. The researchers acknowledge that their method may actually underestimate the effect of these warnings on abortion demand, since many women may turn to local illegal abortion providers that are difficult or impossible to track. But they stand by their conclusion that national pregnancy warnings rather than Zika transmission alone are driving increased abortion demand: “In Latin American countries that issued warnings to pregnant women about complications associated with Zika virus infection, requests for abortion through WoW increased significantly.”
Many women are understandably frightened at the prospect of having a child with significant disabilities, who may require ongoing — and costly — medical care. But there’s a problem with the level of alarm raised by various organizations’ Zika warnings to pregnant women. The latest data on the rate of microcephaly from Zika suggest that abortion demand driven by fear is greatly outpacing the actual risk of birth defects. A study published in the summer in the NEJM estimated that if a pregnant woman has Zika in the first trimester, her child has between a 0.88 percent and 13.2 percent risk of being born with microcephaly — but almost no risk if she is infected in the second or third trimesters. (The range in the first trimester is so wide because of difficulties in determining the rate of infection in the population, as well as uncertainty in the rate of microcephaly cases reported.) Rather than an exact answer, the study provides a current best estimate with an upper and lower limit.
What do these numbers mean for pregnant women? Even assuming that 100 percent of women seeking abortions due to Zika concerns really had the infection in the first trimester, between seven and 113 unaffected pregnancies would be terminated for each one with microcephaly. In Brazil, for instance, among 628 abortion requests likely attributable to Zika concerns, between 545 and 623 children would have been born free of microcephaly, compared with only six to 83 affected children. In Colombia, out of 39 Zika-related abortion requests, no more than five, and possibly none would have developed microcephaly.
But with actual first trimester infection rates likely in single digits, the number of affected pregnancies is almost certainly lower still by an order of magnitude.
Women concerned about Zika in the Aiken study did not necessarily suspect infection, and none were tested for Zika. A woman in Colombia wrote to WoW, “I have no resources at this time and want to ask for your help because fear overwhelms me. What if the baby is born sick?” Another woman in Brazil pleaded, “I need to do an abortion because of the great risk of infection with Zika here . . . Please help me.” Their desperation is driven at least in part by fear founded largely on broad national warnings that suggest every pregnancy may be in grave danger. But even the woman in Venezuela who wrote to WoW “I contracted zika 4 days ago . . . I love children. But I don’t believe it is a wise decision to keep a baby who will suffer,” is far more likely to have a healthy child than one with microcephaly.
If lieu of these warnings, what should be done? Governments and organizations trying to help women faced with Zika should resist alarmism and help them carefully assess their risks. Accurate and up-to-date information about local Zika transmission and everyday preventive measures, such as using insect repellent, window screens and wearing long sleeves and pants, present a more measured strategy to reduce Zika-related microcephaly than extreme pregnancy warnings rooted in fear.