Can You Have a Safe Pregnancy With an ASD or PFO?

Yes, most people with an atrial septal defect (ASD) or a patent foramen ovale (PFO) can have a safe and successful pregnancy. However, because pregnancy places a significant extra workload on your cardiovascular system, these conditions require careful planning, evaluation, and monitoring by a specialized medical team.

How Pregnancy Changes Your Heart’s Workload

During a normal pregnancy, a woman’s body undergoes dramatic physiological changes, including a 30% to 50% increase in total blood volume ^[1]. This means your heart has to pump significantly more blood than it usually does to support the growing baby.

If you have an uncorrected ASD (a hole in the wall between the heart’s upper chambers), this extra blood volume can cause strain. Because the pressure in the left side of the heart is usually higher, blood flows through the hole into the right side—a process called a left-to-right shunt. The extra blood volume of pregnancy forces even more blood through this hole, leading to right-heart dilation and volume overload ^[2]. Over time, this extra strain can increase the risk of maternal arrhythmias or a decline in right ventricular function ^[3].

PFOs, Blood Clots, and Childbirth

If you have a PFO (a small, flap-like opening that didn’t close after birth), the primary concern during pregnancy relates to blood clots. From the first trimester onward, pregnancy is naturally a prothrombotic state—meaning your body’s blood clots much more easily to help prevent dangerous bleeding during delivery ^[4].

During active labor, the intense pushing (often called a Valsalva maneuver) temporarily raises the pressure in the right side of your heart ^[5]. If this pressure becomes higher than the pressure on the left side, it can push the PFO flap open. This reverses the normal flow of blood into a right-to-left shunt ^[6]. If a small blood clot has formed in the veins (which is more likely during pregnancy), this right-to-left flow allows the clot to bypass the lungs’ natural filtering system and enter the main arterial circulation ^[7].

This is known as a paradoxical embolism, and it carries a risk of causing a stroke ^[8]. It is crucial to know that severe complications like this are rare ^[9][10]. However, because the consequences can be serious, doctors take preventative steps to protect you. Many patients wonder if this risk means they must have a C-section, but this is a misconception. In fact, a vaginal delivery is generally preferred because it involves less bleeding and fewer sudden fluid shifts than surgery ^[9]. To protect your heart and minimize the urge to push forcefully, your team will often recommend an early epidural.

Why a Pre-Pregnancy Evaluation is Crucial

Because of these unique demands on the heart, it is highly recommended that women with an ASD or PFO undergo a thorough evaluation before becoming pregnant. This visit should be with a multidisciplinary pregnancy heart team, including a cardiologist who specializes in adult congenital heart disease ^[11].

During this evaluation, you can expect the following:

• Testing your heart: Your doctor will likely order an echocardiogram (an ultrasound of the heart) to check the size of the hole, see if your right heart is enlarged, and ensure you do not have pulmonary hypertension (high blood pressure in the lungs, which makes pregnancy highly dangerous) ^[12].
• Determining your risk level: Doctors use scoring systems—such as the modified World Health Organization (mWHO) classification—to figure out exactly what level of risk a pregnancy poses to you personally ^[13]. This helps determine how often you need check-ups.
• Discussing closure options: If your ASD is causing significant strain, your team may recommend closing the defect before you get pregnant. This prevents permanent changes to the size and shape of your heart muscle ^[14]. Closing the defect using a catheter (without open-heart surgery) is a safe and effective option for most adult patients ^[15].

Managing Your Pregnancy and Baby’s Health

If you are already pregnant or decide to proceed after your evaluation, your pregnancy will be managed by a coordinated team including expert cardiologists, maternal-fetal medicine doctors (high-risk OB-GYNs), and anesthesiologists ^[9].

They will closely monitor you throughout the nine months. Depending on your risk for blood clots, they may prescribe blood thinners (anticoagulants) that are safe for the baby ^[16]. Additionally, because women with congenital heart defects have a slightly higher chance of passing a heart defect to their baby, your doctor will likely schedule a specialized fetal echocardiogram around weeks 18 to 22 of your pregnancy to carefully check the baby’s heart ^[11].