Preterm birth and the lungs By Dr/ Safaa Mokhtar Wafy Professor of chest diseases, Assiut University

In recent years, the number of children surviving premature birth has grown. This means that there is potential to be an increase in the number of children and adults in the future with lung problems due to prematurity.

This fact sheet looks at how preterm birth affects the lungs, what can be done to reduce the impact of problems associated with preterm birth, both as an infant and later in life, and advice for parents of prematurely born babies.

What is preterm birth? The average pregnancy lasts for approximately 37-42 weeks. When a baby is born before the completed 37 weeks of pregnancy, it is considered preterm. Those born before the 28th week of pregnancy are considered extremely preterm.

Severity of preterm birth Week of Pregnancy Late preterm 34 - 36 weeks Moderately preterm 32- 33 weeks Very preterm 28 - 31 weeks Extremely preterm Less than 28 weeks 75% of preterm births are born after 32 weeks, although the babies with the most severe health problems are seen within the ‘extremely preterm’ category.

Nearly 15 million babies worldwide and about 500,000 babies in Europe are born preterm each year, one in ten. In the light of these numbers, preterm infants represent Europe’s largest child patient group and preterm birth has become the major cause of infant death and disabilities from birth in both developed and developing countries.

Are there any risk factors associated with preterm birth? In about half of all cases of preterm birth, the exact cause of the early delivery remains unknown. However, a number of risk factors have been identified which are likely to increase the chances of preterm labour, such as maternal infections, very young or very old (aged under 17 or over 35) mothers, smoking and even passive smoking.

What health problems could affect babies born preterm? Compared with full-term babies, preterm infants are at greater risk of developing health complications. The earlier the baby is born, the less developed its organs will be, and the higher the risk of medical complications later. These include cerebral palsy, sensorial and motor disabilities, learning and behavioural disorders and, commonly, problems with the lungs.

How is preterm birth linked to lung disease? The lungs are one of the last organs to develop as a baby is growing inside the womb. This means that when a baby is born prematurely his/her lungs are not fully developed which may lead to both short and long-term ‘health problems’.

SHORT-TERM EFFECTS OF PRETERM BIRTH INCLUDE: Preterm babies often require special care in the Neonatal Intensive Care Unit (NICU). Preterm babies are at higher risk of death after they go home from the hospital. Preterm babies are at higher risk of being readmitted to the hospital. Two of the most serious problems of preterm birth are respiratory distress and immature brains.

Serious breathing problems are common in premature infants, and may even require that the baby be put on ventilators. These babies may have breathing problems through the first year of life, and increased risk for asthma later. The brain is the last major organ to mature in babies. The immature brain continues to develop even after the time of birth.

Short term problems Bronchopulmonary Dysplasia (BPD)

The most common lung disease affecting preterm babies is a condition known as Bronchopulmonary Dysplasia (BPD). It is characterised by rapid breathing, shortness of breath and gasping and coughing to get more oxygen.

Most infants who develop BPD are born more than 10 weeks before their due dates, weigh less than 2 pounds (about 1,000 grams) at birth, and have breathing problems. Infections that occur before or shortly after birth also can contribute to BPD. Some infants who have BPD may need long-term breathing support from nasal continuous positive airway pressure (NCPAP) machines or ventilators.

The condition usually develops as a consequence of preterm babies being given mechanical ventilation. Although this process is often essential to the survival of the baby it can damage the baby’s lungs, causing inflammation leading to the development of BPD.

These infants' lungs aren't fully formed or aren't able to make enough surfactant. Surfactant is a liquid that coats the inside of the lungs. It helps keep them open so an infant can breathe in air once he or she is born.

Without surfactant, the lungs collapse, and the infant has to work hard to breathe. He or she might not be able to breathe in enough oxygen to support the body's organs. Without proper treatment, the lack of oxygen may damage the infant's brain and other organs. Babies who have RDS are treated with surfactant replacement therapy. They also may need oxygen therapy. Shortly after birth, some babies who have RDS also are treated with NCPAP or ventilators.

BPD can be a temporary condition, but for some children, symptoms can persist into adulthood, increasing the risk of developing chronic lung disease such as chronic obstructive pulmonary disease (COPD).

Infants who have severe BPD may have trouble feeding, which can lead to delayed growth. These babies also may develop: Pulmonary hypertension (PH). PH is increased pressure in the pulmonary arteries. Cor pulmonale. Ongoing high blood pressure in the pulmonary arteries and the lower right chamber of the heart causes this condition.

Recommend tests A chest x ray. A chest x ray can detect problems such as a collapsed lung and show whether the lungs are developing normally. Blood tests. Blood tests can show whether an infant has enough oxygen in his blood. Blood tests also can help determine whether an infection is causing an infant's breathing problems. Echocardiography (echo). to rule out heart defects or pulmonary hypertension as the cause of an infant's breathing problems.

Outlook Advances in care now make it possible for more premature infants to survive. However, these infants are at high risk for BPD. Most babies who have BPD get better in time, but they may need treatment for months or even years. They may continue to have lung problems throughout childhood and even into adulthood. There's some concern about whether people who had BPD as babies can ever have normal lung function. As children who have BPD grow, their parents can help reduce the risk of BPD complications. Parents can encourage healthy eating habits and good nutrition. They also can avoid cigarette smoke and other lung irritants.

Respiratory distress syndrome (RDS) Respiratory distress syndrome (RDS) is a breathing disorder that affects newborns. RDS rarely occurs in full-term infants. RDS is the leading cause of death in babies born prematurely (before 28 weeks of pregnancy ). It occurs in babies whose lungs are not fully developed and their lungs aren't able to make enough surfactant .

RDS might be an early phase of bronchopulmonary dysplasia RDS can lead to a higher risk of developing BPD and severe respiratory infections in the first two years of life and an increased likelihood of asthma later in life.

RDS usually develops in the first 24 hours after birth RDS usually develops in the first 24 hours after birth. If premature infants still have breathing problems by the time they reach their original due dates, they may be diagnosed with BPD. Some of the life-saving treatments used for RDS may cause BPD. Often, the symptoms of RDS start to improve slowly after about a week. However, some babies get worse and need more oxygen or breathing support from NCPAP or a ventilator.

Outlook Due to improved treatments and medical advances, most infants who have RDS survive. However, these babies may need extra medical care after going home. Some babies have complications from RDS or its treatments. Serious complications include chronic breathing problems, such as asthma and BPD; blindness; and brain damage.

Respiratory syncytial virus (RSV) Nearly all babies will contract RSV by the time they are the age of two. For most babies who are born at full term, the symptoms of the virus are similar to a common cold. Full-term babies get antibodies from their mothers during pregnancy which help to fight RSV and other viruses. However, when a baby is born even only a few weeks early, they do not get enough of these antibodies before birth.

This lack of antibodies, combined with the fact that the lungs are not yet fully developed, means that prematurity is the greatest risk factor for severe RSV infection. The symptoms of the virus may include : persistent coughing and wheezing, high fever and sudden gasping for breath.

Parents can help prevent their babies contracting the infection by encouraging those in close contact with the baby to regularly wash their hands, especially before touching the baby, and by cleaning toys, bedding and play areas frequently. They should also prevent anyone smoking near their baby.

Long-term problems

“How will this affect my baby in the long term?" As doctors, we can hear this question often from parents. Whether an infant is born weeks or months early, parents worry about the long-term health effects of prematurity. They want to know what to expect, and how to prevent the problems caused by being born too soon.

Experts are currently unsure about the long-term effects of preterm birth. Medical advancements have led to more babies surviving longer, especially extremely pre-term babies who are now surviving

As this has been a relatively recent development, researchers have not yet been able to assess the long-term impact of preterm birth on the lungs.

As weight and gestational age increase, the risks decrease As weight and gestational age increase, the risks decrease. These risks include: Learning problems: The most common long-term effect of prematurity is some form of learning disability. Disabilities often don’t become apparent until children begin school. Math is most commonly affected; vocabulary and reading are least commonly affected. Early intervention and programs like Head Start can help minimize learning problems to encourage school success.

Vision and hearing problems: Micropreemies are at risk for an eye condition called retinopathy of prematurity (ROP), a condition that can cause vision impairment or blindness. The condition is treated with freezing or with laser surgery, and most infants recover completely.

Feeding and digestive problems: Premature infants often cannot drink from the breast or a bottle at birth, and may be fed with IV fluids or through a tube in the nose or mouth for several weeks. These early feeding challenges can cause long-term feeding difficulties, including food refusal and slow growth. Severe cases of necrotizing enterocolitis may require bowel surgery. Gastroesophageal reflux disease, is another problem that premature babies may have as they grow.

Cerebral palsy: As many as 30% of micropreemies develop cerebral palsy, a condition that affects movement and coordination. The condition may be mild or severe, and mental impairment may or may not be present. Many children with cerebral palsy use braces, wheelchairs.

Respiratory problems: Asthma, croup, and bronchitis are all more common in children who were born early than in children born at term. A more serious complication, bronchopulmonary dysplasia (BPD), is another possible risk of prematurity. Infants with BPD may need extra oxygen for longer periods of time, even after hospital discharge.

There has, however, been research into the effect of preterm birth on school-age children, 1. have a lower exercise capacity compared with full term, 2. increased risk of developing allergic asthma, 3.reduced lung function 4. more airway obstruction problems.

What is the impact of these health consequences? When a baby is born prematurely, they will immediately be taken to a special care baby unit (Neonatal Intensive Care Unit) This can be very distressing for parents as they are separated from their baby so soon after birth, in addition to their baby arriving unexpectedly early.

Parents may be sent home while their baby remains in hospital, or they may be able to return home with their baby and administer oxygen therapy or other treatments from the home. Families caring for a preterm baby often have to face psychological, financial and social costs linked to the long-term health problems of caring for their child.

Many preterm babies, especially those born before 28 weeks, experience related health problems into their adult life, which can be a great social and financial cost to the individual, their family and society.

What can be done to reduce the impact of problems associated with prematurity? Follow-up plan of care and aftercare programme

Healthcare professionals should be able to assist parents at home, through training and education. Whilst this is done well in some countries, some other health care systems do not have an effective follow-up plan in place.

Monitoring for infections Another important area for improvement is improving awareness of the risk of lung infections. If an infection is identified early, it is much easier to manage them.

Better support for parents Parents can often be left feeling helpless when their baby is seriously ill after birth. It is important for them to receive the best information possible and to be signposted to local parent support groups so they can hear experiences from others. If parents and families feel supported they will be better able to manage the potential impact of having a preterm child.

There are parent organisations across Europe, who can provide support networks and information for parents relevant to country. The European Foundation for the Care of Newborn Infants (EFCNI) is the first pan-European organisation and interactive network to represent the interests of preterm and newborn infants and their families.

It gathers together parents, healthcare professionals and stakeholders from different disciplines with the common goal of improving long-term health of preterm and newborn children by ensuring the best possible prevention, treatment, care and support. For more information please see http://www.efcni.org/

Thank you