Pulmonary Hypoplasia

Pulmonary hypoplasia is one of the major concerns associated with very early PPROM, along with extreme premature birth and infection.

The risk is especially important when PPROM occurs early in pregnancy and very low amniotic fluid continues during a period of rapid fetal lung development.

What is Pulmonary Hypoplasia?

Pulmonary hypoplasia means that the lungs have not developed to their expected size or capacity.

Amniotic fluid plays an important role in normal fetal lung development. When very low fluid or anhydramnios continues for a prolonged period, normal lung growth may be affected.

The risk is not the same for every PPROM pregnancy.

Factors may include:

• gestational age when PPROM occurs

• how long very low fluid continues

• amount of residual amniotic fluid

• gestational age at birth

• fetal growth and development

• infection or inflammation

• other pregnancy or neonatal complications

Can Pulmonary Hypoplasia Be Diagnosed Before Birth?

There is currently no single prenatal test that can determine exactly how well a baby's lungs will function after birth.

Ultrasound can provide information about:

• fetal growth

• chest and body measurements

• amniotic fluid

• fetal movement

• other aspects of fetal development

In selected circumstances, fetal MRI may provide additional information about lung volume.

However, prenatal imaging cannot fully predict how an individual baby's lungs will function after delivery.

Lung function is ultimately determined after birth.

The ability to establish ventilation and oxygenation after delivery provides important information about the severity of respiratory disease.

Pulmonary Hypoplasia After PPROM

Babies exposed to prolonged low amniotic fluid can have a wide range of respiratory outcomes.

Some infants may have severe pulmonary hypoplasia and be extremely difficult to ventilate after birth. Others may be successfully supported but require significant respiratory care in the NICU.

Some babies experience respiratory problems related to a combination of:

• pulmonary hypoplasia

• extreme prematurity

• respiratory distress syndrome

• pulmonary hypertension

• bronchopulmonary dysplasia

• infection

• other complications of premature birth

These conditions can overlap, which can make it difficult to determine how much of a baby's respiratory illness is related specifically to pulmonary hypoplasia.

Respiratory Support After Birth

Treatment depends on the baby's individual condition.

Respiratory support may include:

• supplemental oxygen

• continuous positive airway pressure (CPAP)

• mechanical ventilation

• high-frequency ventilation

• surfactant

• medications and treatments directed at pulmonary hypertension

• other neonatal respiratory therapies

Inhaled Nitric Oxide

Inhaled nitric oxide (iNO) is a medication used to reduce pressure in the blood vessels of the lungs in certain newborns with pulmonary hypertension.

It is not routinely given to every premature infant or every baby with PPROM-related respiratory disease.

Current evidence supports a more individualized approach. Some premature infants with pulmonary hypertension and suspected pulmonary hypoplasia after prolonged PPROM or oligohydramnios may benefit from a trial of inhaled nitric oxide.

Whether iNO is appropriate depends on the baby's respiratory and cardiovascular condition and is determined by the neonatal medical team.

Prematurity and Lung Development

PPROM-related pulmonary hypoplasia and prematurity are different problems, but they may occur together.

A baby born very prematurely is still in the process of developing lungs that would normally continue maturing inside the uterus.

When very early birth follows prolonged PPROM and low amniotic fluid, the baby may face respiratory challenges related to both reduced prenatal lung development and prematurity itself.

This is one reason respiratory outcomes after early PPROM vary so widely.

What About Babies With Long Latency?

A long latency allows additional time for overall fetal growth and maturation.

However, more time in pregnancy does not necessarily mean that lung development has been unaffected if very low amniotic fluid continues.

Some babies born at later gestational ages after prolonged early PPROM may still have significant respiratory disease related to pulmonary hypoplasia or abnormal pulmonary vascular development.

Recent research continues to show that prolonged second-trimester PPROM can result in a broad range of respiratory outcomes rather than one predictable pattern.

Can the Lungs Continue to Grow After Birth?

Lung development continues after birth and throughout childhood.

Some infants who survive significant respiratory illness after PPROM show substantial growth and improvement over time.

However, the extent of recovery differs from child to child.

Some children may need:

• supplemental oxygen after discharge

• respiratory medications

• pulmonary follow-up

• monitoring for pulmonary hypertension

• feeding or growth support

• developmental follow-up

Others may eventually require little or no ongoing respiratory treatment.

Protecting Developing Lungs

Families can work with their child's healthcare team to support respiratory health after discharge.

Recommendations may include:

• avoiding tobacco and vaping exposure

• reducing exposure to respiratory infections when appropriate

• keeping recommended vaccines current

• following oxygen or medication instructions

• attending pulmonary and developmental follow-up

• monitoring growth and feeding

Specific recommendations depend on the child's medical history.

Understanding Prognosis

It is natural for families experiencing very early PPROM to ask:

“Will my baby's lungs develop enough?”

Unfortunately, there is no single ultrasound measurement, fluid level, gestational age, or length of latency that can answer that question with certainty.

Current research suggests that outcomes reflect a combination of prenatal lung development, gestational age, amniotic fluid, inflammation, neonatal condition at birth, and response to respiratory treatment.

Every baby's respiratory course is different.

Maternal-Fetal Medicine and Neonatology can help families understand the factors that may affect their individual pregnancy and what respiratory care would be available if premature delivery occurs.

Research & Additional Reading

Current PPROM Respiratory Outcomes

PROMISE — Impact of Maternal and Neonatal Risk Factors on the Respiratory Outcome of Extremely Preterm Infants Following PPROM in the Second Trimester of Pregnancy

Brickmann C, et al. 2026.

Recent research examining respiratory outcomes following prolonged second-trimester PPROM and factors associated with different respiratory courses.

Read the Study on PubMed

Amniotic Fluid and Early PPROM

Amniotic Fluid Volume at Presentation With Early Preterm Prelabor Rupture of Membranes and Association With Severe Neonatal Respiratory Morbidity

Research examining the relationship between amniotic fluid volume after early PPROM and respiratory outcomes.

Read the Study on PubMed

Inhaled Nitric Oxide and Neonatal Pulmonary Hypertension

Inhaled Nitric Oxide in Neonatal Pulmonary Hypertension

Cookson MW, et al.

Reviews the role of inhaled nitric oxide in neonatal pulmonary hypertension, including selective use in premature infants with suspected pulmonary hypoplasia following prolonged rupture of membranes or oligohydramnios.

Read the Article on PubMed

Information reviewed: August 2026