A new study finds that the Zika virus — which has been spreading in Brazil since May 2015 — may cause more problems in developing fetuses than previously believed. Until now, scientists have mainly identified several Zika cases in pregnant women which have resulted in babies born with congenital microcephaly, a condition in which a baby’s brain is underdeveloped and part of its head is missing.

But a new study out of Yale School of Public Health and the Hospital Geral Roberto Santos in Salvador, Brazil suggests that infection may be linked to stillbirths and tissue damage beyond the brain. The study describes the case of a pregnant Brazilian woman infected with the virus who gave birth to a stillborn baby in January. The baby is the first to have shown signs of severe tissue swelling outside of the central nervous system (CNS) — whereas previously congenital Zika virus was thought to only attack the brain and CNS. The study also links congenital Zika virus with hydrops fetalis — a fetal disorder in which abnormal amounts of fluid build up in the fetus’ body parts, which usually results in death.

The woman, 20, started out with a normal pregnancy that quickly changed during the 18th week. An ultrasound showed that the baby was extremely underweight for its stage of development as a result of congenital Zika virus, though the mother hadn’t shown any Zika virus symptoms.

“These findings raise concerns that the virus may cause severe damage to fetuses leading to stillbirths and may be associated with effects other than those seen in the central nervous system,” Dr. Albert Ko of the Yale School of Public Health, an author of the study, said in the press release. “Additional work is needed to understand if this is an isolated finding and to confirm whether Zika virus can actually cause hydrops fetalis.”

However, the researchers note that not many conclusions can be made about a single case. They aren’t able to directly link the stillbirth or hydrops fetalis to the Zika virus, and most researchers still cannot confirm whether Zika indeed leads to microcephaly, either. For the time being, researchers must continue their investigations into Zika’s link to birth defects.

Source: Ko A, et al. PLOS Neglected Tropical Diseases, 2016.