Even though she was born with a heart defect, Candace Martinez managed to give birth to a daughter, Elliott. (COURTESY OF CANDACE MARTINEZ)

For years, the one thing standing between Candace Martinez and motherhood was her heart. She was born with a defect that a generation earlier would have led to death as an infant, but modern medicine — open-heart surgery at 5 weeks old to switch two misconnected arteries — had saved her. At age 18 she experienced heart failure: Her heart muscle couldn’t pump enough blood to oxygenate her body. At 19, she got a pacemaker.

Martinez survived, but she always assumed that the life modern medicine had given her would not include having children. Pregnancy and childbirth long were thought to be too tough on women with congenital heart defects like hers.

Not anymore. Recommendations adopted in January by the American Heart Association suggest that, with careful supervision and management, many complex congenital heart defects should not be a deterrent to pregnancy.

For Martinez, 33, of Bakersfield, Calif., the recommendations couldn’t have come soon enough. After spending the early part of her pregnancy in the Ronald Reagan UCLA Medical Center and the rest of it near the hospital, she gave birth to a baby girl on Valentine’s Day. The pregnancy wasn’t exactly easy: Martinez’s heart at one point started beating abnormally and doctors administered electric shock to get it back to a normal rhythm. But her daughter is healthy and she is, too.

“Where we used to think pregnancy was not feasible or a prohibitively high risk” for women with complex heart defects, said her UCLA cardiologist Jamil Aboulhosn, one of the authors of the new AHA guidelines, “many of these women can actually tolerate pregnancy, but they’re still high-risk pregnancies” that should occur in places with appropriate infrastructure and practitioners who know how to care for such patients.

It is easy to forget how risky pregnancy and childbirth are in general. Maternal death — historically a leading cause of mortality for women — remains a concern today, and cardiovascular diseases are the top culprit. Among women who die during pregnancy or within a year afterward, cardiovascular causes account for more than 4 in 10 deaths, according to the Centers for Disease Control and Prevention.

The heart has to work hard to grow a baby, explained Brian Koos, Martinez’s obstetrician at UCLA. Pregnancy increases a woman’s blood volume by 50 percent, and her heart must work 30 to 50 percent harder to pump enough oxygenated blood throughout the body. The mother’s heart rate rises in the second half of pregnancy, and she is at a higher risk for an irregular heartbeat, called arrhythmia, and for blood clots, Koos said.

Pregnancy for women with complex heart defects can be even more of a threat. The new recommendations focus on complex congenital heart disease, such as having a ventricle with two outlets, having extra or missing or transposed arteries — as Martinez had — or having only one ventricle. An estimated 10,000 babies are born in the United States with these defects each year, and more than 117,000 adults are living with them.

“Women who have impaired heart function don’t have the cardiac reserve that’s required to meet these demands,” Koos said. But women have always had the choice to conceive, and “motherhood is a very strong force,” Koos added.

Until the 1960s, fewer than 10 percent of infants with complex congenital heart disease survived to adulthood, Aboulhosn said. But advances in cardiac surgery in the 1960s and 1970s substantially extended survival for these children. Surgeries such as the atrial switch, which Martinez had to correct the flow of oxygenated blood in her heart, and the Fontan procedure, which redirects blood to the pulmonary artery in those with a weak or absent right ventricle, became more common. By the 1980s, they were the standard of care for complex heart defects. By the 1990s, an arterial switch replaced the atrial switch, with seemingly better outcomes. (See sidebar.)

A 2013 study found that more than three-quarters of infants born between 1979 and 2005 with complex congenital heart defects survived past their first birthday.

“Today there is virtually no [heart] defect that can’t have some form of surgical intervention performed from the time of birth,” said Mary Canobbio, a cardiac nurse at UCLA and chair of the group that wrote the AHA recommendations.

More than 90 percent of these children now reach adulthood, which has led to uncharted territory: caring for adults with complex congenital heart disease.

“Doctors were reporting on the outcomes of these surgeries in the ’80s, but no one was addressing pregnancy,” Canobbio said. Pregnancy was discouraged in these women, but some conceived anyway, forcing medical professionals to learn how to care for them.

“We showed that yes, they can get pregnant. The next question was ‘Should they get pregnant?’ and that is the issue that has really plagued cardiologists,” Canobbio said. Debate continues today, particularly regarding women in areas without a cardiac center for adults with congenital heart disease.

While careful management of these pregnancies has allowed better outcomes, that doesn’t mean all women with a complex congenital heart defect should conceive. A woman’s cardiologist considers her clinical history, medications and the results of exercise stress tests, an EKG, an echocardiogram and other assessments to determine her risk.

The risk of becoming pregnant remains too high for some, such as those with Eisenmenger syndrome, a condition involving pulmonary hypertension (high blood pressure in the lungs), reversal of blood flow and cyanosis, in which oxygenated and unoxygenated blood mix together. The overall U.S. maternal mortality rate is two deaths per 10,000 women, or 0.02 percent. In women with Eisenmenger, it’s 30 to 50 percent, and more than a quarter of their babies die.

Most women with congenital heart disease who die as a result of pregnancy had conditions considered too risky for them to have attempted childbirth, Canobbio said.

“It is critical that these patients be given counseling well before they get pregnant,” Canobbio said. “If we don’t get the problems controlled before pregnancy, we potentially have a disaster.”

After conception, a woman like Martinez needs care from an obstetrician, a cardiologist, a nurse with specialized training and an anesthesiologist — a multidisciplinary team whose cooperation and communication are vital to her management. One major risk is heart failure: The heart simply may not be able to keep up with pregnancy’s demands. Another is arrhythmias, both during and after pregnancy. Treatment might involve medication, a pacemaker insertion, bed rest or a cardioversion, in which an electric jolt resets the heart’s rhythm.

Fetal risks exist, too. Miscarriages occur more often in some of these women. More than a quarter of newborns have complications, such as being underweight, not growing well in the womb and respiratory distress at birth.

“The data show we can get you through a pregnancy if you’re clinically stable at the time of conception,” Canobbio said. “What we don’t know is if the burden of pregnancy is going to shorten the mother’s life span.”

But “that’s the risk you take,” said Erica Thomas, a 37-year-old from Costa Mesa, Calif., who was born with a single ventricle, an atrial septal defect (a type of hole in the heart) and a missing tricuspid valve. What saved her life was the Fontan procedure she had as a newborn.

“The majority of my younger years were all survival,” Thomas said. “They didn’t expect me to live, and it was about being a guinea pig.” When she was 6, her parents moved the family from Colorado to Los Angeles because high altitude was too risky for her. Today, she has a healthy 5-year-old daughter and 2-year-old son.

“My husband and I never thought we would be able to have our own biological children,” Thomas said. “We’re just grateful to have had that opportunity.”

Before getting pregnant, “we asked Mary [Canobbio] a lot of questions because I wasn’t sure I wanted to be a guinea pig when I’m bringing another life into this. But knowing there were other people who went before me really helped us in making our decision.”

In her first pregnancy, Thomas’s water broke at 35 weeks, five weeks before a planned induction, and she suffered complicated swelling and pain postpartum. In her second pregnancy, her water broke at 23 weeks, requiring hospitalization in hopes of getting her pregnancy to last 10 more weeks.

She made it, but her son was still preterm, as up to 65 percent of these women’s children are. That’s why many women like her stay in the hospital or in a hotel close to a center for adults with congenital heart disease for weeks leading up to their induction date. That strategy paid off for Martinez when her daughter came early.

“I got to hold her immediately, and that was amazing,” said Martinez, who just experienced her first Mother’s Day as a mother. “She was so tiny, and it just melts your heart.”