PH Seen in More Than Half of Preterm Infants in Dutch Study

These babies were more likely to develop bronchopulmonary dysplasia

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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More than half of babies born preterm at a center in the Netherlands were found to have pulmonary hypertension (PH), a new study reports.

Babies with PH were more likely to develop bronchopulmonary dysplasia (BPD), a breathing disorder where the lungs don’t develop correctly, and survival outcomes were poorer for babies with PH.

“In our prospective cohort, early-PH, with an occurrence of 55%, was highly prevalent in preterm infants and associated with significant morbidity,” the researchers wrote.

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“Further studies are needed to investigate whether identification of early PH and its phenotype [characteristics] will allow for customized preventive therapies, aiming [for] the reduction of long-term sequelae,” they added.

The study, “Clinical significance of early Pulmonary Hypertension in Preterm Infants,” was published in The Journal of Pediatrics.

BPD is a complication of extreme prematurity, which includes babies born before 28 weeks of pregnancy. PH has a well-known link with BPD, mortality, and long-term cardiorespiratory complications in infants born preterm.

In this study, the researchers intended to determine the prevalence of PH early in life and to analyze its characteristics in regards to predictive value for BPD development and survival.

The study and its findings

They reported outcomes for 104 preterm babies born between 2016 and 2019 at the University Medical Center Groningen in the Netherlands. Preterm babies were defined as infants born before 30 weeks of pregnancy and/or weighing less than 1,000 grams (just over 2 pounds).

All of the included children had echocardiogram (ECG) data available from about one week after birth. Of the 104 babies, more than half — 57, or 55% — were found to have early PH.

The median follow-up time was just over one year. Of the 104 premature babies in the study, 45 (47%) developed BPD; 15 of these cases were classified as severe. Eight of the babies died before 36 weeks post-menstrual age (PMA, which is the time between the first day of the last menstrual period and birth plus the time elapsed after birth).

Overall, premature babies with PH tended to have a lower gestational age and lower Apgar scores (a measure of newborn health). They were also more likely to receive mechanical ventilation and oxygen supplementation and more frequently developed BPD.

Among the children with PH, 35 (61%) had flow-PH — low pulmonary resistance blood flow and continuous passage of blood from the aorta to the pulmonary arteries — while 12 (21%) had persistent pulmonary hypertension of the newborn, called PPHN, which is caused by abnormal resistance in the lung’s blood vessels.

The remaining 10 (18%) babies were classified as “PH without-shunt,” meaning there was increased blood pressure in the lungs (i.e., pulmonary hypertension), but without the shift in heart blood flow that usually accompanies PH (called a shunt).

Statistical analyses showed that flow-PH and PPHN were associated with significantly increased risk of developing BPD.

PPHN also was associated with significantly worse survival outcomes in the statistical analyses. While flow-PH showed a trend toward worse survival outcomes, the difference from outcomes for premature babies without PH did not reach statistical significance.

“We found that early-PH, in particular PPHN, correlated with decreased survival,” the researchers wrote. “However, though we observed a tendency toward increased mortality in infants with flow-PH, we did not find flow-PH or PH without-shunt to be significantly associated with decreased survival.”

PH without-shunt also showed no association with BPD. The team noted that most of these babies were diagnosed with PH via indirect measures due to the lack of the characteristic shunt, writing that these findings “underscore the clinical need for improved tools to more robustly diagnose PH in preterm infants without a shunt.”

The team called for further research into whether early identification of PH type in preterm babies could facilitate personalized management to ultimately improve clinical outcomes.