In about four-fifths of cases, Zika causes no noticeable symptoms so women have no idea if they contracted it during pregnancy. Test kits for the virus are only effective in the first week of infection and only available at private clinics at a cost of 900 reais ($225), more than the monthly minimum wage.
At Recife's IMIP hospital, dozens of soon-to-be mothers wait anxiously for ultrasound scans that will indicate whether the child they are carrying has a shrunken head and damaged brain, a condition called microcephaly. The hospital has already had 160 babies born there with the deformity since August.
"It's very frightening. I'm worried my daughter will have microcephaly," says Elisangela Barros, 40, shedding a tear behind her thick-rimmed glasses. "My neighborhood is poor and full of mosquitoes, trash and has no running water. Five of my neighbors have Zika."
Women like Barros, who live in crowded, muddy slums of Brazil's chaotic cities, have little defense against the Aedes aegypti mosquito that carries Zika, as well as other diseases such as dengue and yellow fever. They often cannot afford insect repellent and have little access to family planning.
Three-month-old Daniel, who was born with microcephaly, undergoes physical therapy at the Altino Ventura foundation in Recife.
Shocking images of babies with birth defects have made many women think twice about getting pregnant.
Doctors worry the outbreak will lead to an increase in dangerous clandestine abortions in the majority-Catholic country. Under Brazilian law, terminating pregnancies is illegal except in cases of rape and when the mothers' life is at risk.
The rapid spread of Zika to 22 countries in the Americas has prompted some governments to advise women to delay having children. El Salvador recommended women not get pregnant for two years.
It has also triggered debate on liberalizing abortion in the region, where many countries have strict laws.
"Fear is growing among women becau Ninety percent of children born with the condition will have retarded mental and physical development, and will need specialized care for the rest of their lives se this is a new disease that we know little about. We don't have many answers," said Adriana Scavuzzi, a gynecologist at the IMIP hospital.
Brazil's health ministry said as of Jan. 23 there were 270 confirmed cases of microcephaly and a further 3,448 suspected cases since October are being investigated — by far the most in the Americas.
World Health Organization (WHO) officials say there is no scientific proof that Zika stunts the development of the fetus, causing microcephaly, but it is strongly suspected.
Ninety percent of children born with the condition will have retarded mental and physical development, and will need specialized care for the rest of their lives. There is no certainty what they will be able to see or hear, or when they will learn to walk and talk, Scavuzzi said.
Scavuzzi compared the emergency to the Thalidomide tragedy of the 1960s when thousands of children, mostly in Europe, were born with deformed limbs due to the use of the pill to help pregnant women with insomnia and morning sickness.
"It will be worse than the Thalidomide generation because then the cause could be withdrawn from the market," she said. "But how do you withdraw from circulation a mosquito that has lived with us for so long?"
Zika, first identified in Uganda in 1947 and unknown in the Americas until discovered in Brazil last year, causes a mild fever and body aches, symptoms that disappear in five days and can be mistaken for dengue, a virus that infected 1.6 million Brazilians last year.
With a health crisis on its hands, Brazil's government says women who want to get pregnant should discuss the risks with their doctors but has stopped short of telling them to delay.
Instead, it plans to hand out insect repellent to tens of thousands of low-income pregnant women and is stepping up an offensive to eradicate the mosquito with the help of the army.