What is trisomy 18? Why the fatal genetic disorder is in the news — and what it's like to get the diagnosis.

Trisomy 18 is a fatal chromosomal condition that can be detected during pregnancy. It's also at the center of a new legal case in Texas, where a mom of two, Kate Cox, is seeking an abortion after discovering her unborn child has the devastating condition. Texas bans abortions after six weeks.

Cox's case has made national headlines, and it's also raised a lot of questions about trisomy 18, a condition that's often feared by expectant parents. Here's what you need to know.

What's happening with the case?

Cox is 20 weeks pregnant and filed a lawsuit last week to ask a district court in Austin, Texas, to temporarily block the state's restrictive abortion ban. Her unborn baby was diagnosed with trisomy 18 and is not expected to live more than a few days outside the womb, per the lawsuit. Cox is currently unable to get an abortion in the state due to its abortion laws.

Cox has visited three different emergency rooms in the past month due to severe cramping and undiagnosable fluid leaks, her lawsuit says. She has had two C-sections in the past, and her lawsuit alleges that continuing the pregnancy “puts her at high risk for severe complications threatening her life and future fertility, including uterine rupture and hysterectomy.”

Cox wrote an editorial published by the Dallas Morning News, stressing that this child was wanted but will not survive. “I do not want to continue the pain and suffering that has plagued this pregnancy or continue to put my body or my mental health through the risks of continuing this pregnancy,” she wrote. “I do not want my baby to arrive in this world only to watch her suffer.”

Last Thursday, Judge Maya Guerra Gamble granted a temporary restraining order against the state that would allow Cox to immediately have an abortion. “The idea that Ms. Cox wants so desperately to be a parent and this law may have her lose that ability is shocking and would be a genuine miscarriage of justice,” Gamble said during the proceeding.

But Texas Attorney General Ken Paxton later warned Cox’s doctor that she could face civil and criminal penalties if she performs the abortion. The lawsuit is trying to protect the doctor, as well as Cox's husband — both could face serious legal consequences under the state's Senate Bill 8, which bans abortion and aiding in a person having an abortion.

The Texas Supreme Court then issued an administrative stay blocking the lower court judge's decision, USA Today reports. After Molly Duane, Cox's attorney, said this would temporarily keep Cox from accessing medical care, it was announced Monday, Dec. 11 that the Texan mother had left the state to terminate her pregnancy., per Reuters. “She’s been in and out of the emergency room and she couldn’t wait any longer,” Nancy Northup, head of Center for Reproductive Rights, which represents Cox, said in a statement.

On Monday night, the Texas Supreme Court reversed Gamble's ruling allowing Cox to seek an abotion under the state's "medical emergency" exception.

What is trisomy 18 and why is it fatal?

Trisomy 18 — also known as Edwards syndrome — is a chromosomal condition that is fatal in all but very rare cases, Dr. Silvana Ribaudo, an ob-gyn at NewYork-Presbyterian/Columbia University Irving Medical Center, tells Yahoo Life. “It is almost always lethal,” she says. Trisomy 18 causes several life-threatening medical problems, often including heart defects and organ abnormalities, and many babies with the condition die before they're born or within the first month of life.

Five to 10% of children born with trisomy 18 live past their first year, but they often have severe intellectual disabilities, according to Medline Plus. In addition to heart defects and organ abnormalities, trisomy 18 can cause a small head and deafness, according to the American College of Obstetricians and Gynecologists. Children with the condition often have clenched fists with overlapping fingers and clubfeet (feet that are turned inward), per the Cleveland Clinic.

The condition happens in about one in 5,000 infants who are born alive, but many fetuses with the condition don't survive to term, per Medline Plus. Any pregnant woman can have a child with trisomy 18, but the odds go up as a woman gets older.

Trisomy 18 is usually so severe that babies who survive after birth are given comfort care, the Cleveland Clinic says. There is no cure for the condition, and treatment is usually unique to the child, based on the specific abnormalities they have. Children who survive often have trouble eating normally and may need a feeding tube, and they may have spinal issues that impact how they move.

The Cleveland Clinic breaks down the devastating statistics for children with trisomy 18 who survive past birth:

• 60% to 75% survive to their first week.

• 20% to 40% survive to their first month.

• No more than 10% survive past their first year.

The 10% who survive past their first birthday need significant support from family and caretakers and almost never learn to walk or talk. “Because the syndrome is usually severe, the quality of life for children who live past one year usually requires a tremendous amount of supportive care and intervention," women's health expert Dr. Jennifer Wider tells Yahoo Life.

“Patients are offered a termination in this setting, given that this condition is generally not compatible with life,” Ribaudo says. “There are ethical issues around treatment for newborns with trisomy 18 due to the high death rate and the difficulty in predicting which infants will live beyond their first year. The majority who are born will pass away after suffering from heart failure, respiratory failure or neurological problems. Ethical committees are often involved in decisions regarding whether to pursue palliative — comfort — care versus invasive and intensive care.”

How can you be tested for it?

There are several potential tests for trisomy 18. “Ultrasound screening can begin in the first trimester,” Erica MacDonald, a genetic counselor at Corewell Health, tells Yahoo Life. “Blood draws are available as early as 10 weeks of pregnancy.”

“These screening tests are highly accurate for detection,” Dr. Kartik Venkatesh, a high-risk obstetrician and perinatal epidemiologist at Ohio State Wexner Medical Center, tells Yahoo Life.

Additional testing to confirm the diagnosis includes chorionic villus sampling (CVS), which is done between 10 and 13 weeks of pregnancy, Venkatesh says. This test takes a small sample of cells from the placenta to look for genetic conditions. Another testing option is amniocentesis, which can be done between 15 and 20 weeks of pregnancy and involves taking a sample of amniotic fluid to test for trisomy 18 and other health conditions, Wider says.

“The diagnostic test with CVS or amniocentesis can be quickly, safely and accurately performed in the office with ultrasound by a maternal fetal medicine specialist with definitive results back from the lab within one week after sampling of the early placenta or amniotic fluid,” Venkatesh says.

MacDonald notes that it's rare — a less than 1% chance — for someone to have another pregnancy impacted by trisomy 18. “There are rare cases where the chance may be higher due to either parent having a chromosome difference themselves,” she says. “Also, the baseline chance for any woman to have a child with trisomy 18 increases as they get older, so a person’s age-related chance must be considered as well.”

What is it like?

Other families have shared their stories of experiencing a devastating trisomy 18 diagnosis.

“It made me open my eyes.”

Melissa, a 40-year-old mother in Arizona, told The Cut that getting a trisomy 18 diagnosis changed her view on abortion. “I used to work as a patient-care tech in a hospital in the mother-baby wing. I had a mom who delivered a trisomy 18 baby,” Melissa shared. “The baby, I thought, would not live past the first shift that I worked. I worked three night shifts in a row, and the baby was still alive. But it was struggling to breathe, struggling on its own fluids because its esophagus didn’t connect to its stomach. It was tragic. I’m just somebody from the outside going in to check the mom’s vitals, and I saw how bad this was.”

Melissa was given several expensive options to travel to get an abortion and ultimately got pills from Mexico to do a medication abortion at home. Melissa, who was previously against abortion, says the experience “made me open my eyes.”

“Our boy has no chance.”

Lauren Miller, a 36-year-old Texas mom, kept a diary of her pregnancy with twins for the Guardian. It details everything from her excitement at learning she would have twins to trying to seek abortion care after learning that one of her babies had trisomy 18.

“I want to throw up. I can’t even come up with words to describe how devastating this is,” she wrote after learning of the diagnosis. “Our boy has no chance.” Miller described her doctor eventually saying to her, “This baby isn’t going to make it to birth. You need to go out of state.”

Miller ended up needing to travel to Colorado to have an abortion for her baby with trisomy 18. “Someday, I will hold my boys and tell them that I love them and that for a few weeks, they had a little brother named Thomas,” she wrote. “Thomas, who never lived but will be with us forever. I will explain that mercy can be heartbreaking. I will explain that the abortion for their brother was out of love.”

“Phoebe made us better people, reminding us of the value of life.”

Sarah Bellman wrote an opinion letter to the Columbus Dispatch in October, detailing her decision to continue her pregnancy with a baby she named Phoebe, who was stillborn. “Early on, we were told she had trisomy 18 and was ‘not compatible with life,’” Bellman wrote. “I carried her for 34 weeks while we purposefully loved her every day. She passed peacefully. Although we couldn't bring Phoebe home or hold her alive, she was very much alive inside me. We did not lose a pregnancy, nor did we lose a ‘potential human being.’”

“We lost a daughter, sister, cousin and granddaughter,” Bellman continued. “Phoebe made us better people, reminding us of the value of life. She taught us to love more fiercely.”

“We made the painful decision to end our very wanted pregnancy.”

Anabely Lopes, 44, made headlines in early 2023 when she shared that she needed to travel from her home state of Florida to Washington, D.C., to get an abortion after discovering her baby had trisomy 18.

Florida law allows exceptions to save the woman’s life, prevent serious injury or in situations where the baby has a fatal fetal abnormality, but two doctors are required to state in writing that the abortion is medically needed, per the Miami Herald. Lopes said her doctors were too afraid to write the letters confirming that she needed an abortion.

“We felt it was our duty to protect our daughter from neglectful suffering if she were to make it to term,” Lopes said. “We made the painful decision to end our very wanted pregnancy.”

“We weren’t too optimistic going into the delivery. We didn’t bring a car seat.”

Professional golfer Hayden Springer told the Fort Worth Star-Telegram in April 2021 that he and his wife, Emma, didn't expect to take their daughter Sage home after she was given a trisomy 18 diagnosis during Emma's pregnancy.

“If you Google ‘trisomy 18’ and talk with doctors, it’s pretty grim. We weren’t too optimistic going into the delivery,” Springer said. “We didn’t bring a car seat. We literally had nothing just because we were told her life was likely going to be 24 to 72 hours after birth. But she makes it through those 48 hours, the doctor does an [echocardiogram] on her heart ,and it’s a little bit different than what she was prenatally diagnosed with.”

After two and a half months in the hospital, a tracheostomy and a gastrostomy button, Sage came home. “It’s been a long road, but we’ve been blessed to have her at home,” Springer said at the time. “For the meantime, she’s doing well and growing.”

Sage died in November 2023, according to an Instagram post by Springer. Funeral attendees were asked to wear pink in her honor.