Feature Article – October 2026

Pulmonary Hypertension in Neonates with Congenital Diaphragmatic Hernia (CDH)

An Overview of What, How, and Why

By Olivia Mashburn, CRNP, NNP-BC

What is pulmonary hypertension (PH)?

To understand pulmonary hypertension originating in the perinatal period, it is imperative to remind ourselves how the transition from fetal to neonatal life occurs. Throughout fetal life, pulmonary vascular resistance (PVR) remains high relative to systemic vascular resistance, as the placenta acts as a low-resistance reservoir for blood. Elevated PVR presents no issue in fetal life, as the placenta acts as the site of gas exchange (rather than the alveoli). The alveoli remain fluid-filled and require being fluid-filled in order to appropriately distend and grow. In utero, fetal lung tissue receives only about ten to fifteen percent of fetal cardiac output, with the remaining majority of cardiac output shunting away from the lungs and into the aorta (through the ductus arteriosus).1

At birth, successful transition from intrauterine to extrauterine life depends on a drop in pulmonary arterial blood pressures (relative to systemic blood pressure). This is normally primarily achieved by two important factors: the first neonatal breath, and the clamping of the umbilical cord.

The first breath allows the neonatal lungs and alveoli to take over the role of gas exchange by means of pulmonary vasodilation and clearance of lung fluid. When oxygen (a pulmonary vasodilator) reaches the pulmonary blood vessels and promotes relaxation, the subsequent drop in pulmonary vascular pressure allows significantly more pulmonary blood flow, as right ventricular output is re-directed through the lungs. This is necessary in facilitating gas exchange achieving appropriate oxygenation in neonatal life. As the entry of air mechanically forces the clearance of alveolar fluid, which also substantially decreases pulmonary vascular resistance.2

The clamping of the umbilical cord effectively removes the placenta as a low-resistance reservoir, thereby increasing systemic vascular resistance. Assuming that air has entered the neonatal lungs and that pulmonary blood flow has increased prior to clamping the umbilical cord, the lungs become the alternate low-resistance pathway for blood flow. The separation from placental circulation also removes the neonate’s exposure to circulating pulmonary.2

When pulmonary arterial blood pressure remains elevated in neonatal life, this constitutes pulmonary hypertension (PH). This sustained elevation of pulmonary arterial blood pressures presents a problem in neonatal life because blood continues to shunt from away from pulmonary circulation and towards systemic circulation, as it did in fetal life, however because the lungs are now responsible for oxygenation (rather than the placenta), any significant bypass of the newborn lungs means that poorly oxygenated blood is being pumped out into circulation. This results in hypoxemia. While failure to transition from fetal to postnatal life is not the only cause of pulmonary hypertension, the underlying physiology remains the same. There are, however, varying etiologies of PH, each with their own implications for management. There are five major types or “groups” of PH as classified by the World Health Organization (WHO),3,8 with “group 3” being PH caused by lung disease and hypoxia. Group 3 pulmonary hypertension will be the focus of this brief review, as this is the classification of PH that is typical of neonates with congenital diaphragmatic hernia (CDH).

How does PH develop and persist in the setting of CDH?

Neonates with congenital diaphragmatic hernia (CDH) have lung hypoplasia resulting from restricted lung growth and direct mechanical compression, both by the herniated abdominal contents (affecting the ipsilateral lung) and sometimes too by mediastinal shift (affecting the contralateral lung). As a result of the pulmonary hypoplasia, these neonates also have pulmonary blood vessels that are smaller in size. For these neonates, achieving the same cardiac output as a neonate with normally sized pulmonary blood vessels requires and increase in blood pressure within those affected vessels. Over time, the pulmonary blood vessels undergo remodeling (i.e. thickening of the vessels walls along with endothelial dysfunction)4 secondary to the increased pressure. Vascular remodeling occurs by complex processes involving factors such as retinoic acid, endothelial nitric oxide, endothelin, micro RNAs, and vascular growth factors.4,5 Given these vascular structural changes, PH can persist for weeks to months, even after surgical repair of the diaphragm and subsequent improvement in cardiac function and respiratory status.6-7

What can we do as clinicians?

Management of neonates with pulmonary hypertension resulting from congenital diaphragmatic hernia is largely individualized and tailored to the patient’s specific needs. Some strategies that are often used include gentle ventilation, pharmacologic sedation, pulmonary vasodilator therapy, extracorporeal membrane oxygenation (ECMO), and thoughtful timing of surgical repair.10 Non-pharmacological methods to reduce agitation and noxious environmental stimuli (such as containment, dim lights, and minimization of loud noises) are accessible and impactful tools in stabilizing neonates with PH. The clinical courses of these neonates can change quickly, and the care team plays a critical role in keeping these patients stable. Nurses at the bedside and in the nurse practitioner role alike have both opportunity and ability to make lasting impact when providing care.

References

  1. Bajaj, H. (2025). Transition from fetus to neonate. Surgery (Oxford), 43(11), 693-698.
  2. Hooper, S. B., Roberts, C., Dekker, J., & te Pas, A. B. (2019, December). Issues in cardiopulmonary transition at birth. In Seminars in Fetal and Neonatal Medicine (Vol. 24, No. 6, p. 101033). WB Saunders.
  3. Gelzinis, T. A. (2022). Pulmonary hypertension in 2021: part I—definition, classification, pathophysiology, and presentation. Journal of Cardiothoracic and Vascular Anesthesia, 36(6), 1552-1564.
  4. Montalva, L., Antounians, L., & Zani, A. (2019). Pulmonary hypertension secondary to congenital diaphragmatic hernia: factors and pathways involved in pulmonary vascular remodeling. Pediatric research, 85(6), 754-768.
  5. Perveen, S., Frigeni, M., Benveniste, H., & Kurepa, D. (2022). Cellular, molecular, and metabolic aspects of developing lungs in congenital diaphragmatic hernia. Frontiers in pediatrics, 10, 932463. https://doi.org/10.3389/fped.2022.932463
  6. Holden, K. I., Rintoul, N. E., McNamara, P. J., & Harting, M. T. (2024, August). Congenital diaphragmatic hernia-associated pulmonary hypertension. In Seminars in pediatric surgery (Vol. 33, No. 4, p. 151437). WB Saunders. https://doi.org/10.1016/j.sempedsurg.2024.151437
  7. Sankaran, D., Lakshminrusimha, S., & Lim, M. J. (2025). Cardiorespiratory transition in CDH. Seminars in Fetal and Neonatal Medicine, 101649. https://doi.org/10.1016/j.siny.2025.101649
  8. Mocumbi, A., Humbert, M., Saxena, A., Jing, Z. C., Sliwa, K., Thienemann, F., Archer, S. L., & Stewart, S. (2024). Pulmonary hypertension. Nature Reviews Disease Primers, 10(1), 1. https://doi.org/10.1038/s41572-023-00486-7
  9. Altit, G., Lapointe, A., Kipfmueller, F., & Patel, N. (2024, August). Cardiac function in congenital diaphragmatic hernia. In Seminars in Pediatric Surgery (Vol. 33, No. 4, p. 151438). WB Saunders.
  10. Pala, C., & Blake, S. M. (2023). One size does not fit all: Congenital diaphragmatic hernia management in neonates. Neonatal Network, 42(1), 45-51. https://doi.org/10.1891/NN-2021-0039

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