Mosquito bites remain the primary way the virus is spread, although sexual transmission is possible.
The US Centers for Disease Control and Prevention said on Tuesday it was investigating 14 new reports of possible sexual transmission of the mosquito-borne Zika virus, including several involving pregnant women.
In two of the suspected cases, the infection has been confirmed in women whose only known risk factor was sexual contact with an ill male partner who had recently travelled to an area where the virus is present, the agency said.
Testing of the male partners is still pending, the CDC said.
Mosquito bites remain the primary way the virus is spread, although sexual transmission is possible, the agency added.
© Thomson Reuters 2016