Ms Norashikin Baharul Hisham is keeping all the windows in her flat shut, even though it gets stuffy.
The 31-year-old housewife, who is five months pregnant, is afraid of letting in mosquitoes which carry the Zika virus.
The Ministry of Health said yesterday a pregnant woman living in the cluster around Sims Drive and Aljunied Crescent had been infected. But expectant mothers everywhere are fretting, even those who do not live near the affected areas.
Zika is associated with microcephaly in unborn babies, a birth defect in which they are born with abnormally small heads.
Ms Norashikin, who lives in a Bukit Batok rental flat, tries not to go out in the day and keeps her windows shut against the Aedes mosquito, which spreads the virus.
"I cannot sleep at night because I am so worried," she said.
Housewife Alice Seo, who is 21 weeks pregnant, left Singapore for San Francisco to see friends and family a few days before the outbreak. The 36-year-old is now wondering whether to stay abroad for a while longer or even give birth in the United States.
"My husband and I are still thinking about it, and trying to weigh the pros and cons," said the American who is based here.
"But (the latest news) sways me more towards staying in the States a little longer until the Zika situation gets under control."
Some mothers-to-be are choosing to go out less, avoiding open areas and checking their homes for stagnant water. Administration executive Elin Tay, 39, who is seven weeks pregnant, said: "I used to go to the mall, but now I only go to work and to the hospital."
Joo Chiat resident Koh YL, who is 37 weeks pregnant, said she and her husband discussed moving to her mother's place in Lucky Heights. They had even joked about having her labour induced early, although they later decided not to explore that option, said the 37-year-old editorial consultant.
Dr Wee Horng Yen, an obstetrician and gynaecologist at O & G Care Clinic, said inducing labour was not advisable.
"Instead, women near term can exercise strict precautions of avoiding being bitten and abstinence from sexual intercourse," he said.
Allied educator Juliana Jamal, 29, who is expecting her third child any day now, said: "I just pray this baby comes out quickly before anything can happen."
•Additional reporting by Linette Lai