Premature Babies and their Problems

Prematurity used to be defined as a baby of less than 2.5kg at birth. WHO defines prematurity as babies born before 37 weeks from the first day of the last menstrual period. Very low birth weight (VLBW) babies are those that weigh less than 1.5kg. Some would add a category of extremely low birth weight (ELBW), weighing less than 1.0kg.
There are really two different problems of small babies. One is prematurity that means being unready for the extra-uterine world. The other is small for dates (SFD) that represents intrauterine growth retardation (IUGR). The former is often reluctant to feed and needs much encouragement whilst the latter has been starved and has a voracious appetite. However, it is not uncommon for babies to be both early and to have suffered IUGR.

About 7 to 10% of babies are born before 37 weeks gestation. There are racial differences in normal birth weight so that if the parameter of weight alone is taken there may be babies of Indian race who are wrongly labelled whilst being full term and healthy. About 7% of babies in the UK weigh less than 2.5kg at birth, rising to 10% in deprived areas such as Hackney.¹
Simply labelling all babies born before 37 weeks as premature fails to illustrate the marked gradation in terms of severity of the problem with increasing prematurity. A baby born at 36 weeks will probably be a little slow to feed. A baby born before 33 weeks will have more serious problems including, possibly, immature lungs. Birth before 28 weeks causes very significant problems but the survival rate of babies born before 28 weeks is quite remarkable nowadays. Quoting figures may be misleading as they will vary considerably amongst units but figures that are not atypical include 90% survival if over 800g, 50% survival if over 500g and 80% survival before 28 weeks. These figures may also hide significant disability in survivors.

There are a number of risk factors for early delivery.

• Induction or, more likely, Caesarian section, may have been undertaken because of serious adverse intrauterine conditions. This may include fulminating pre-eclampsia or abruptio placentae. The decision that has to be made is to consider the circumstances and the maturity of the baby and to ask, "Is the baby safer in or out?" This is a matter of balancing risks.
• Multiple pregnancy often leads to premature labour and this may be very early if multiple means more than twins. Other causes of a large uterus such as polyhydramnios may be involved.
• The classical story of cervical incompetence is one of progressively earlier labours in successive pregnancies with premature rupture of membranes and a painless early dilation of the cervix. A common cause of this was dilatation of the cervix above Hegar 10 as this caused rupture of fibres in the cervix. This should be less common nowadays as termination of pregnancy usually involves prostaglandins rather than forced dilation to Hegar 14 or above and the operation of D&C has fallen from favour.
• Low socio-economic status, inadequate or absent antenatal care and poor maternal nutrition all predispose to premature labour. Smoking and excessive alcohol consumption are also risk factors.
• Heroin withdrawal or too rapid reduction of methadone during the last trimester can induce premature labour. Drug abusers must be encouraged to comply closely with their regimen and reduction of methadone should be slow in the last trimester. Cocaine can also cause premature labour. It is a potent vasoconstrictor and this can have a devastating effect on placental function.
• Small babies are more likely with a mother under 17 of over 35 years old.
• Bacterial vaginosis predisposes to premature labour.

The premature baby will look small and unprepared for this world. The baby who is also SFD may have little subcutaneous fat and the skin may appear wrinkled.
The premature baby faces a number of problems that may be accentuated if there was IUGR too.

• Hypothermia is a great risk, especially if there is little subcutaneous fat. A premature baby is less able to shiver and to maintain homeostasis.
• Hypoglycaemia is also a risk, especially if SFD. There may also be hypocalcaemia. Both can cause convulsions that may produce long term brain damage.
• The more premature the baby, the greater the risk of respiratory distress syndrome. Steroids before delivery may reduce the risk but it is still very real. If the baby requires oxygen it must be monitored very carefully as if the levels are too high the premature baby is susceptible to retrolental fibroplasia and blindness.
• The premature baby is more susceptible to neonatal jaundice and to kernicterus at a lower level of bilirubin than a more mature baby.
• They are susceptible to infection and to necrotising enteritis.
• They are susceptible to intraventricular brain haemorrhage with serious long term effects.

All these are problems faced by the neonatologist in the Special Care Baby Unit but when the baby is eventually discharged from hospital and goes home with the family, that is not the end of problems. The baby who is just slightly premature will probably have little on no long term problems but those who are very premature and who have a stormy start to life often suffer many and serious problems.

When a baby is in SCBU it is a very emotional and traumatic time for both the parents, not just the mother. They should be encouraged to visit and stay with the baby as much as possible. Breast feeding may be rather difficult but it should be encouraged.² Breast milk is the best food for any baby but especially premature babies. Mothers who are producing more than their own baby needs should be encouraged to donate to the local SCBU as it is always welcome.
The baby is attached to monitors and has tubes in and out of the body. It may not be possible to hold the baby or it may not be possible to do so for long. This should be encouraged as much as is compatible with the safety of the baby but bonding is much more difficult than with a normal, healthy, full term baby.
Whilst trying to keep a positive attitude, the parents must also come to terms with the fact that the baby could well die. There may also be difficult decisions about switching off ventilators and the expected quality of life if the child survives. Doctors in the "front line" may not be as good at communicating with parents as is ideal and it is also difficult for parents to take in what they are told at such an emotional time.³ They may wish to discuss matters with the familiar face of their family doctor who is outside the hospital but who understands the issues involved.

Immunisations

Premature babies need to be protected by immunisations as much as any other baby and prematurity is not a contraindication to immunisation even if the immune system may be immature. The timing of immunisations is based on the child's chronological age from birth and not on the child's putative age based on maturity.⁴

Figures about outcomes for premature babies have to be interpreted with a degree of circumspection to be sure that like is being compared with like. Percentages should be taken with caution. Different studies use different criteria for the degree of prematurity for inclusion. What is quite clear is that the more premature a baby might be, the greater the risk of death and the greater the risk of handicap in those who survive. There is a gradation of risk. Being both premature and light for dates would seem to add further to the risk.
A study from Leicester, published in 1999, showed that during a 3 years period, 249 infants of 26 weeks gestation or less were admitted to the neonatal unit. Of these 66 (26.5%) survived to be discharged from the neonatal service. A further 7 infants died before the age of 2 years. Of the remaining 59, there were 55 that could be followed up. Of these, 36 had no features of severe disability although only 30 children could be be considered entirely normal. Infants born before 26 weeks gestation and admitted for neonatal intensive care had around a 12% chance of normal survival to 2 years. A slightly smaller proportion of infants survived with significant disability.⁵

Sight and hearing

Severe problems such as cerebral palsy, blindness and deafness may affect as many as 10 to 15% of significantly premature babies. About 1 in 4 babies with birth weight below 1.5kg has peripheral or central hearing impairment or both.⁶
Birth weight below 1.5kg, gestational age of less than 33 weeks and retinopathy of prematurity (ROP) are all risk factors for developing treatable refractive errors and strabismus. At present there is no formal policy on follow up.⁷ In England and Wales in 2001, there were about 7500 live births under 1500 g who needed screening for ROP, many on several occasions. Although most extremely preterm babies develop some degree of ROP, severe disease is relatively rare. In a multicentre study, 66% of babies under 1.25kg developed ROP, but only 18% reached stage 3, and 6% required treatment.⁸

Follow up to school

Researchers have been watching the development of all babies in the UK who were born at least 15 weeks before term (25 weeks gestation or less) during the first 10 months of 1995. Of those 308 children who survived, 241 underwent formal psychological assessment using standard cognitive, language, phonetic and speech tests, with teachers rating their school achievement. Of those children 40% were found to have moderate to severe learning difficulties and boys were twice as likely to be adversely affected as girls.⁹ The rates of severe, moderate, and mild disability were 22%, 24%, and 34%, respectively. Disabling cerebral palsy occurred in 30 children representing 12%. Among children with severe disability at 30 months of age, 86% still had moderate-to-severe disability at 6 years of age. In contrast, other disabilities at the age of 30 months were poorly predictive of developmental problems at 6 years of age. Hence it seems that improvement may occur but it is less likely with greater severity.
Another study has suggested that children who were very premature may deteriorate rather than improve. They compared children at the age of 8 and 15 and found that full IQ dropped from an average of 104 to 95 and that the number needing extra educational provision rose from 15 to 24%. These were the same children assessed at 8 and 15 and so it does not represent better neonatal care in the younger ones. Results indicate that between the ages of 8 and 15 years there is an apparent deterioration in neurodevelopmental outcome category, cognitive function, and extra educational support. It is not clear whether this represents a genuine deterioration in neurocognitive function or whether it represents the expression of pre-existing cerebral pathology in an increasingly complex environment.¹⁰

Behavioural and psychomotor problems

A study from Liverpool has looked at children of 7 and 8 who were born before 32 weeks and who were well enough to attend mainstream school.¹¹ They were compared with full-term children of similar age in their class at school.
Disabilities can be subtle and numerous and so a range of tests was used. The preterm children had a higher incidence of motor impairment, and this affected how well they did at school even when their intelligence was normal.
Over 30% had developmental coordination disorder (DCD) compared with 6% of classmates. The preterm children were significantly more likely be overactive, easily distractible, impulsive, disorganized and lacking in persistence, and to overestimate their ability. Attention deficit hyperactivity disorder (ADHD) was found in 8.9% of the preterm children and 2% of controls.
The children who had been the most premature were not necessarily those with the lowest scores. Although major disabilities have been reduced, the levels of disability tested here did not seem lower than those found in children born 10 or 20 years earlier, despite changes in care of the newborn.

Brain development

IUGR may be very important in terms of early growth of the brain leading to poor IQ and developmental skills.¹² Individuals who were born before 33 weeks gestation continue to show noticeable decrements in brain volumes and striking increases in lateral ventricular volume into adolescence.¹³

Emotional development, teens and beyond

A study of teenagers in mainstream schools who were born before 29 weeks gestation showed that compared with mainstream classmates, they have higher levels of parent and teacher reported emotional, attentional, and peer problems well into their teens. Despite these problems, they do not show signs of more serious conduct disorders, delinquency, drug use, or depression.¹⁴
A study of 18 and 19 years olds who were born before 33 weeks gestation showed that they had different personalities from controls with increased neuroticism and decreased extraversion scores. This was more marked in females than males.⁸
A study of pre-term children who had reached 19 to 22 years of age showed that they were, on average, shorter than their contemporaries, more likely to use prescription medicines and less likely to have attended higher education.¹⁵

The safest place for a child to develop is in utero and so it is important to try to prevent premature labour or such complications that very early delivery is indicated. There may be times when the intrauterine environment is so adverse that the baby is safer out than in. Antenatal care is important. Problems of social deprivation, poor maternal nutrition and substance abuse must all be addressed. Smoking should cease and, as explained in the article on fetal alcohol syndrome, alcohol consumption should be kept very much in moderation and there may be no safe lower limit. If cervical incompetence is suspected a Shirodkar suture has been the treatment since about 1948.

The success of improved survival in very premature infants has raised some serious ethical issues. It is now possible to save more and more smaller and earlier babies but is this a good thing?
Such babies have a very high incidence of both physical and behavioural problems. This may be blindness, deafness, mental handicap or ADHD. Is the quality of life really worth the enormous input?
The term bed blockers is usually used pejoratively of the elderly but tiny, very early babies spend a very long time in SCBU cots that are in short supply. They may be depriving other babies of facilities from which they would extract greater benefit. The cost of SCBU care is also very high and finance is not a limitless resource.
Not all premature babies are disasters as shown by the list of famous premature babies on the premature babies uk website. It includes Albert Einstein, Isaac Newton and Charles Darwin.
When should neonatologists decide that the quality of life that they salvage is not worthy of the effort? When would it be better to let tiny babies die? This is a very difficult question that will raise much passion and prejudice but it is an extremely important issue that does require sober assessment.
The quite incredible survival rates that are achieved by some units for very premature babies has fuelled a debate about the upper limit for termination of pregnancy.