Pregnancy With Idiopathic PAH May Be Riskier Than Other Types

Higher rates of complications, mortality with iPAH than LHD-PH

Joana Vindeirinho, PhD avatar

by Joana Vindeirinho, PhD |

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A pregnant woman cradles her belly.

Pregnant women with idiopathic pulmonary arterial hypertension (iPAH) had higher rates of mortality and pregnancy complications than those with other types of PAH or pulmonary hypertension due to left heart disease (LHD-PH), according to a study in China.

The prevalence of babies born with low birth weight was also higher in mothers with iPAH (PAH without a known cause), as well as with LHD-PH, than with other PAH types.

“iPAH patients should be advised to prevent pregnancy,” the researchers wrote, adding that “standardized and multidiscipline-assisted maternal management is the key to improving maternal-fetal outcomes” for people with pulmonary hypertension (PH) who are or wish to become pregnant.

The study, “Pregnancy outcomes in women with pulmonary hypertension: a retrospective study in China,” was published in BMC Pregnancy and Childbirth.

Pulmonary hypertension (PH) is a chronic, progressive disease marked by increased blood pressure in the blood vessels that supply the lungs, which causes the heart to overexert and can lead to heart failure. Pregnancy causes additional strain on the cardiovascular system, which increases the risk of pregnancy complications and death in people with PH.

Although improvements in treatments and pregnancy management have reduced mortality rates, the risks remain high and current guidelines for PH recommend careful counseling for a fully informed decision.

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Assessing different PH types

Researchers in China retrospectively evaluated pregnancy and fetal outcomes in women with PH, separated by type, to provide clinical data to help doctors manage these high-risk pregnancies.

They collected data from 154 pregnant women with PH who were admitted to one hospital in Guangzhou between January 2011 and December 2020. The women were 30.9 years old on average and most (83.8%) had regular obstetric examinations during pregnancy. The main method of delivery was cesarean section, in 108 (70.1%) women.

The patients either had a clinical diagnosis of PH, had a cardiac echocardiography during pregnancy, or had been transferred to the intensive care unit (ICU) for monitoring. Patients with systolic pulmonary artery pressure (sPAP) — the pressure in the pulmonary artery during a heartbeat of 36 mmHg or higher — were considered to have PH.

The study population was divided by PH type. The World Health Organization classifies PH into five general groups and several subcategories, based on the underlying cause of the disease. The most frequent PH type was LHD-PH, with 62 (40.3%) patients, followed by PAH related to other diseases (oPAH) with 45 (29.2%), PAH associated with congenital heart disease (CHD-PAH) with 41 (26.6%), and iPAH with six (3.9%).

Of the 154 women assessed, 149 (96.8%) survived and five (3.2%) died within a week after delivery —  three (50%) in the iPAH group, one (2.4%) in the CHD-PAH group, and one (1.6%) in LHD-PH.

All five were diagnosed with PH during pregnancy, did not have regular obstetric examinations before admission, and had cardiac function class 4 at admission — meaning symptoms are present even when a patient is resting and worsen with any activity — as assessed by the New York Heart Association (NYHA) functional classification.

The researchers noted that pregnant women with PH are at higher risk of heart failure, pulmonary hypertensive crisis, or sudden death at weeks 32–34. “Therefore, for patients with cardiac function classifications of [3 or 4], our multidisciplinary team suggests that the pregnancy be terminated at an early stage,” they wrote.

In the overall group, 54 women (35.1%) were admitted to the ICU due to critical conditions, with the highest rate observed in the iPAH group (83.3%) and the lowest in the oPAH group (24.4%). The iPAH group also had the highest prevalence of heart failure and failure of more than one organ system (called multiple organ dysfunction syndrome or MODS).

Fetal outcomes

The researchers also assessed fetal outcomes. They found that 66 (42.9%) of infants were born preterm (earlier than 37 weeks gestation) and 94 (61.0%) were small for their gestational age.

Three infant deaths (1.9%) were recorded within a week after birth, one each in the CHD-PAH, oPAH, and LHD-PH groups. Additionally, 15 (9.7%) cases of therapeutic abortion, seven (4.5%) intrauterine deaths, and one (0.65%) missed abortion (when the fetus stops developing) were recorded.

A substantial proportion of infants also had weight issues: 44 (28.6%) had low birth weight — less than 2,500 grams (5.5 pounds), but more than 1,500 g (3.3 pounds) — 20 (13%) had very low birth weight (between 1,000 g, or 2.2 pounds, and 1500 g), and five (3.2%) had extremely low birth weight (lower than 1,000 g). Infants with low birth weight were more frequent in the iPAH and LHD-PH groups.

The study showed significant differences in maternal and fetal outcomes between different PH types and subtypes, with iPAH patients having higher mortality and prevalence of pregnancy complications than the others.

“Clinicians must balance the pros and cons of maternal and fetal outcomes and choose the most appropriate treatment plan to improve [them],” the researchers wrote.

The study also highlighted the importance of proper PH management during pregnancy. Of the six women in the iPAH group, the three who survived received targeted treatment to help reduce pulmonary arterial pressure and alleviate cardiac burden, and saw their condition improve. The other three were transferred from other hospitals in critical condition.

Because of this, the researchers suggested that “hospitals should establish multidisciplinary assistance teams, including obstetrics, cardiovascular medicine, critical medicine, anaesthesiology and neonatology specialists.” They noted, however, that, as a retrospective study done at a single center, the group might not be representative of the general population.

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