Orders for abortion pills by women in seven Latin American countries with Zika outbreaks increased after health officials in those countries warned that the virus might cause severe birth defects, according to a women’s organization supplying such pills.

Orders from women in Brazil, Ecuador and Venezuela roughly doubled, while those from Colombia, Costa Rica, El Salvador and Honduras went up by from 36 percent to 76 percent, researchers said in a study published Wednesday by The New England Journal of Medicine. The authors of the study included a leader of the group based in Amsterdam that is supplying the pills, Women on Web, a nonprofit staffed by doctors helping women from countries where abortion is illegal or restricted to terminate unwanted pregnancies.

Even with the increase in demand for abortion pills, the number of orders received by Women on Web from Latin America and the Caribbean in that time period was small: slightly more than 2,300 in the region, with about 1,600 of those in countries where health authorities had warned about Zika’s potential to cause brain damage.

In the countries where Zika warnings were issued, there are typically about 3.5 million abortions per year, said Gilda Sedgh, the principal research scientist at the Guttmacher Institute, a reproductive health research organization which was not involved in the study.