Zika-infected babies born with normal-sized heads can still see a slowing in head and brain growth and the onset of microcephaly after their delivery, a report published Tuesday by the Centers for Disease Control and Prevention shows.

Scientists already had discovered that babies with normal-sized heads can have a range of issues associated with what's collectively known as congenital Zika syndrome, including problems with eating, vision, hearing and movement.

The new study, however, examines the first group of infants with evidence of congenital Zika virus infection and documented occurrences of microcephaly after birth. Microcephaly is a Zika-linked birth defect in which a baby's head is smaller than normal, with his or her brain potentially smaller and underdeveloped as well.

"This report documents that microcephaly at birth is not an essential hallmark of congenital Zika syndrome," authors of the report wrote. "Infants with normal [head circumference] at birth have brain and other abnormalities associated with congenital Zika syndrome and might develop microcephaly after birth."

For the study, researchers examined the cases of 13 infants in Brazil who were born with evidence of congenital Zika virus infection and normal head size. Eleven later developed microcephaly.

The infants were born between October 2015 and January, and evaluated between October 2015 and October of this year.

Zika began to draw widespread attention in 2015, after a reported surge of microcephaly cases in Brazil among babies whose mothers were infected with the virus during pregnancy. In advising women about their pregnancies, doctors have used imaging to watch for microcephaly, which may be possible to detect at the end of the second trimester or beginning of the third.