Erica Thomas was born with several heart defects.

At birth her outlook was poor, and her early years were focused on staying alive.

“We had to move to low altitude away from family and friends. I didn't play competitive sports as a kid and often would require a modified version of P.E. in school and sometimes even academic assistance,” Thomas told Healthline.

The 37-year-old has undergone three major heart surgeries as well as a pacemaker implantation for her four heart defects — a trial septal defect (ASD), single ventricle defect, pulmonary atresia, and tricuspid atresia.

She is one of 2.5 million people in the United States living with congenital heart defects. About 1.4 million are adults.

Since 2000, the number of people with heart defects who are living into adulthood has increased by 63 percent.

Read more: Get the facts on congenital heart disease »

Pressure on the heart

A growing number of women with congenital heart defects are now hoping to become pregnant.

Under new guidelines from the American Heart Association (AHA) this may now be possible for some of them.

Traditionally, doctors have advised women with complex congenital heart conditions not to get pregnant, due to the pressure both pregnancy and childbirth place on the heart.

According to the AHA, “changes from pregnancy tax the heart and circulatory system. Blood volume increases by about 40 percent, cardiac output increases 30 percent to 50 percent, and heart rate rises 10 to 20 beats per minute.”

Such changes dramatically impact the cardiovascular system, and in women with congenital heart defects this poses a particular risk.

“A major concern is whether the heart muscle is strong enough to sustain the physiological changes of normal pregnancy,” Mary Canobbio, R.N., chair of the statement-writing group for the new guidelines, and lecturer at the University of California, Los Angeles (UCLA), School of Nursing, told Healthline.

“If the muscle is already weak by the cardiac condition, the extra burden can cause further weakening,” she added. “Other changes, primarily hormonal can lead to irregular heart rhythms (arrhythmias) ... especially in those women who have had arrhythmias before conception. Some of these are quite serious and can be fatal.”

Canobbio notes another concern is the changes in pregnancy that can increase the risk of developing clots. Some heart conditions are prone to clot formation before conception, and pregnancy may increase the risk of thrombosis (a clot), embolism (a clot that travels), and stroke.

Read more: Women need to get heart checkups in their 20s »

Pregnancy a possibility

The new set of recommendations from the AHA is providing the medical community with the guidance to help women with congenital heart defects have successful pregnancies.

“This really represents a shift in thinking and offers new hope for a growing segment of our society,” said Canobbio in a press release.

Among the recommendations, the AHA suggests women undertake extensive preconception testing and counseling, to determine if they can safely deliver a baby.

If the woman is deemed able to safely have a baby she should then work alongside a team of specialists including an OB-GYN trained in high-risk pregnancies, as well as a cardiologist.

“The good news is that for the majority of women with congenital heart disease, the risk of pregnancy is small. But for a number of defects, especially those considered complex, the risk is much higher and it is this group of women who must have not only preconceptional counseling but need to undergo full diagnostic evaluation to determine her risk before becoming pregnant,” Canobbio told Healthline.

Canobbio says tools now available to manage high-risk pregnancies are instrumental in ensuring a successful pregnancy for women with congenital heart defects.

However, there will still be some women for whom pregnancy is deemed too high risk. In these cases, such women will be discouraged from becoming pregnant.

For those that are given the “all clear” to deliver a baby, the recommendations suggest that women deliver at a large medical facility that has sufficient resources to respond to any medical emergencies.

After delivery, doctors should carefully monitor the woman’s heart function for at least six weeks and in some cases up to six months. This is to check for any long-term damage that may have occurred due to the pregnancy.

In both of Thomas’ pregnancies, her team of cardiologists closely monitored her. She was given regular echocardiograms, stress tests, electrocardiograms, and blood pressure tests.

Regular ultrasounds from her obstetrician as well as echocardiograms for the fetus were also undertaken.

Read more: Men’s and women’s hearts age differently »

A personal tale of precaution

Before both of her deliveries, Thomas was transferred via ambulance from her local medical facility to UCLA with a specialized nurse on board.

Despite her water breaking early in both of her pregnancies and a 74-day stay in the hospital prior to a cesarean delivery for her second baby, both Thomas and her two children are healthy.

“One of my first questions to my cardiology team regarding family planning was, ‘Have there been other patients who have done this and what were the outcomes?’” Thomas said.

“Our decision to go forward was primarily based on my health and the recommendations of my medical team. We would not have moved forward if there were any major concerns about my well-being and my heart's ability to handle pregnancy,” she told Healthline.

“If there are tools and resources out there to increase our vitality and longevity, and the ability to possibly bear children, then let’s make them available to everyone everywhere,” she added. “The best way to make an informed decision is to be informed.”