WASHINGTON — The number of women infected with the Zika virus during their pregnancies in the continental United States has risen to 234, health officials said on Thursday.

Officials from the Centers for Disease Control and Prevention declined to say how many of the women had given birth, citing confidentiality concerns for the women and their families. But they did cite six cases with abnormalities — three babies with birth defects and another three who died before birth with evidence of defects.

The numbers raised more questions than answers. Without knowing the total number of births, officials cannot know if the babies with birth defects represent a tiny fraction of the total, or a large part. The agency said some of the defects were related to microcephaly, a condition linked to Zika that causes brain damage and abnormally small heads. Others, like eye problems, were Zika-related, but not caused by microcephaly.