Two weeks ago, Jenny Tolosa found out she was pregnant.

The 23-year-old had no idea. "I didn't have any symptoms," she says. "I totally didn't expect this." She giggles, because she was excited by the news.

But she was also worried. She says her first thought was, "I think I had Zika last December!"

That's the mosquito-borne virus that's spreading through Latin America — and has been linked to the birth defect microcephaly, which causes an abnormally small head and possible brain damage.

Like Tolosa, the nation of Colombia is on edge. More than 30,000 people there have contracted the Zika virus, including more than 5,000 pregnant women. And health officials are now bracing for the possibility that many of these women will have babies with abnormalities.

That's why, at 3 p.m. on a weekday afternoon, Tolosa is sitting in the suffocatingly hot maternity section of a health clinic in the northeastern city of Cucuta. The clinic is packed with anxious women waiting to get an ultrasound exam, which doctors can use to look for signs of microcephaly. Tolosa has been here for hours and the specialist hasn't even arrived yet. She came extra early so she could be first in line. She hopes a scan might give her more information.

Tolosa works odd jobs on a farm and doesn't earn a lot. She's on Colombia's equivalent of Medicaid.

Still, when her relatives heard she was pregnant, they pooled their money so she could get an ultrasound right away to make sure Zika hadn't affected the fetus.

There were no signs of microcephaly. But that was two weeks ago.

Now Tolosa is here for a second ultrasound — this one paid for by the government — and all her anxieties are flooding back.

One of the doctors at this clinic, Henry Munoz Martinez, says patients like Tolosa have become the new normal here. Over the past several months they've seen about 150 pregnant women who have been exposed to Zika.

The women are "really tense, really stressed out," he says. It's hard to know what to say to them, he adds.

So far there's no definitive proof that these women's babies will be in any danger. And in Colombia there have been no reported cases of abnormal births linked to Zika. But the virus started spreading here a lot later than in Brazil, where there have been thousands of cases of microcephaly reported since the fall, so it could be just a matter of time.

"It's worrisome because you just can't guarantee that the fetus will develop normally," says Munoz. "You can't guarantee that it will all end happily with no complications."

For now, Colombia's government has instructed clinics to register every case of a woman who was infected with Zika while she was pregnant. The idea is to follow her through to the birth.

Jessica Vanessa Paredes, who's 19, has come for her first visit. Her father brought her to the clinic earlier in the day because she thought she might be pregnant. A blood test showed that she was right.

She's still holding her head in shock as the nurse starts running through some questions. At the top of his list: Have you had symptoms of Zika?

Yeah, says Paredes, in November. The nurse looks up sharply. That was around the time she got pregnant. He leans forward intently. Does she know the exact date she got sick?

Paredes turns to her father. "It was during my birthday, right?"

"Yeah," says her father. "November 20."

Based on the time frame, the nurse believes the Zika infection was probably over by the time Paredes got pregnant. Still, he says, there's always the chance.

"We're going to need to monitor you," says the nurse, "to make sure there aren't any malformations. OK?"

"What God wants," says the father.

Paredes barely musters a goodbye as she walks out the door.

Back in the hallway there's a sudden stir. The doctor who does the ultrasounds has finally arrived.

It's time to call the first patient — Jenny Tolosa. By now she's been waiting for five hours.

She practically runs into the room.

She pulls up her shirt and grimaces, just a bit, as the doctor spreads the ultrasound jelly on her stomach.

The doctor calls out measurements for the body parts he sees on the screen, including the head.

The ultrasound done, the doctor takes out a manual to check the measurements against the list of what's normal at this stage.

Tolosa stands with her hands on her hips, lips pressed tight as she watches the doctor flip through the pages. It feels like an eternity before he says: "Normal. Es un normal."

Everything looks good, the doctor explains. For now there's nothing to suggest there's microcephaly.

Tolosa is beaming as she leaves the room. She bounds over to her husband and collapses into giggles.

"This is what I was hoping for," she says.

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