PREMATURITY
INTRODUCTION
Preterm birth is defined as birth before 37 weeks of gestation (World Health Organisation (WHO), 2019).Sub-categories of preterm birth are based on weeks of gestational age: moderate to late preterm (32 to 37 weeks), very preterm (28 to 32 weeks), and extremely preterm (less than 28 weeks; WHO, 2019).
Preterm birth is often associated with low birth weight (less than 2500g; WHO, 2014).Low birth weight may be further categorised into very low birth weight (less than 1500g) and extremely low birth weight (less than 1000g; WHO, 2014).
Preterm birth and low birth weight are major predictors of perinatal mortality and morbidity (Cutland et al., 2017).According to the Australian Institute of Health and Welfare (AIHW; 2019), 72% of babies born preterm are admitted to neonatal intensive care units or special care nurseries.Preterm birth is also associated with increased risk of readmission during the first year of life and long-term neurological disability (WHO, 2012).
According to Spittle et al. (2011), preterm infants are at significantly increased risk of motor delay and Cerebral Palsy (CP).With preterm birth, the human brain is particularly susceptible to cerebral white matter injury which disrupts the normal progression of developmental myelination (Back, 2018).The risk of developing CP increases with decreasing gestational age.For infants born at term (ie. 40 weeks’ gestation), there is a 0.1% risk of developing CP (Spittle et al., 2011).This risk increases to 6.2% of infants born at 28 to 32 weeks’ gestation and 14.6% of infants born at 22 to 27 weeks’ gestation (Spittle et al., 2011).
Infants born preterm and at low birth weight are often referred to physiotherapy whilst in the Neonatal Intensive Care Unit or Special Care Nursey.Physiotherapists also closely monitor preterm infants following neonatal discharge, to monitor their development and facilitate referral to early intervention services if necessary (Sharma, Samuel, & Aranha, 2018).
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RISK FACTORS
According to the AIHW (2016), the greatest risk factors for premature births include:
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Multiple births (ie. triplets and higher)
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Mothers residing in remote areas
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Mothers of < 20 years and ≥ 40 years
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Mothers smoking during pregnancy
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Mothers consuming alcohol during pregnancy
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Mothers with pre-existing or gestational diabetes
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Social disadvantage and lower levels of maternal education
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Previous preterm birth
OBJECTIVE ASSESSMENT
DEVELOPMENTAL MILESTONE SCREENING
For more information on developmental milestone screening
HEAD AND NECK SCREENING
For more information on head and neck screening
SPINE AND TRUNK SCREENING
For more information on spine and trunk screening
HIP SCREENING
For more information on hip screening
FOOT SCREENING
For more information on foot screening
REFLEXES AND TONE
For more information on reflexes and tone
ALBERTA INFANT MOTOR SCALE
The Alberta Infant Motor Scale (AIMS), is a commonly used screening tool that examines infants’ gross motor maturation from birth to 18 months or when the infant begins to independently walk (Spittle et al., 2015). Through focusing on attainment of gross motor milestones and components necessary to attain the milestones, the AIMS may be used to accurately predict infants at risk of gross motor delay (Spittle et al., 2015).
Test Administration
The assessment involves observing an infant’s spontaneous movements in prone, supine, sitting and standing with minimal handling (Baliker, 2015). Depending on the infant’s stage of development, they may require assistance to assume the four positions. To transition infants between the four positions, the following instructions may be used as a guide:
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Whilst supporting the infant’s cervical spine, gently lower them into a supine position on the mat
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Encourage the infant to roll into prone by placing a toy outside their reach or by gently guiding their upper hip into side lying
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Encourage the infant to roll back into supine by placing a toy outside their reach or alternatively by guiding their hip or shoulder into supine
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Holding the infant’s wrists, gently pull them into a seated position
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Holding the infant’s axillar region, bring them into a supported standing position
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Test Scoring
The AIMS scoring sheet consists of 58 items, including 4 positions: prone (21 items), supine (9 items), sitting (12 items) and standing (16 items). Each item is scored as ‘observed’ or ‘not observed’. The items between the least and most mature items observed, represent the ‘motor window’. Each item within the ‘motor window’ is awarded 1 point if ‘observed’. 1 point is awarded for each item prior to the least mature item. Points for each subscale are added. The sum of the 4 subscales provides the total score and may be plotted on the percentile graph for the appropriate age.
Figure 29. AIMS Scoring (Katz, 2011)
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Predictive Capacity
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The predictive capacity of the AIMS varies based on the age of the infant at the time of evaluation. Infants below the 10th percentile at 4 months and below the 5th percentile at 8 months may be considered valid and reliable indicators of motor developmental delay or abnormality (Baliker, 2015).
HAMMERSMITH INFANT NEUROLOGICAL EXAMINATION
The Hammersmith Infant Neurological Examination (HINE) is a simple, scoreable, standardised clinical neurological examination for infants between 2 and 24 months of age. The HINE cut-off scores provide prognostic information on the severity of motor outcomes (Romeo, Ricci, Brogna, & Mercuri, 2016). Moreover, the HINE may assist in early detection, diagnosis and prognosis of infants at risk of developing Cerebral Palsy (CP) and other neuromotor disorders (Romeo et al., 2016).
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Test Administration
There are three parts to the HINE: a neurological examination (which is scored), developmental milestones and behaviour (which are not scored). The scorable neurological examination is comprised of 26 items, which are divided into 5 domains, assessing cranial nerve function, posture, quality and quantity of movements, muscle tone and reflexes and reactions (Cerebral Palsy Alliance, 2018a).
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The HINE scoring sheet contains instructions and diagrams for each item which are intended to guide the therapist when completing and scoring the various assessments (Romeo et al., 2016).
Figure 30. HINE Assessment (Romeo et al., 2016)
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Test Scoring
Each item is scored individually (0, 1, 2, or 3). The maximum score for any one item is a score of 3, and the minimum is a score of 0. A sub-score is given to each section, and the overall global score is calculated by summing all the 26 items (range: 0-78), with higher scores indicating better neurological performance (Cerebral Palsy Alliance, 2018a).
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Predictive Capacity
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The HINE has good sensitivity and high predictive value for risk of CP in infants under 5 months of age. A HINE score of <57 at 3 months is 96% predictive of CP (sensitivity 96% and specificity 87%; Cerebral Palsy Alliance, 2018a). For infants over 5 months of age, the HINE has 90% predictive accuracy for detecting the risk of CP (Cerebral Palsy Alliance, 2018). Scores below 40 are predictive of non-ambulant CP, whilst scores between 40 and 60 are predictive of ambulant CP (Cerebral Palsy Alliance, 2018a).
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PRECHTL GENERAL MOVEMENTS ASSESSMENT
The Prechtl General Movements Assessment is a standardised test of movement that may be scored based on observation of an infant’s movement (Einspieler, Bos, Libertus, & Marschik, 2016). General Movements (GMs) are distinct spontaneous movement patterns that are evident in babies up to 20 weeks corrected age. They are seen when the baby is awake, calm and alert, and not externally stimulated (such as when a parent is playing or talking with them; Einspieler et al., 2016).
The Prechtl General Movements Assessment is predictive of how the young central nervous system is developing. If GMs are identified as ‘absent’ or ‘abnormal’ it may indicate risk of neurological conditions, in particular Cerebral Palsy (CP; Cerebral Palsy Alliance, 2018b).
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Test Administration
A video of an infant’s general movement patters may be taken in a supine position by a parent or clinician with appropriate consent. For infants up to 6 to 9 weeks corrected age, a video of at least 10-minute duration should be collected. For infants between 6 to 9 weeks corrected age to 20 weeks corrected age, a video of at 3-5-minute duration should be collected (Cerebral Palsy Alliance, 2018b).
Test Scoring​
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Certified assessors trained by the General Movements Trust will score the infant’s movements, and determine whether the movement patterns observed are normal, abnormal or absent (Cerebral Palsy Alliance, 2018b).
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Writhing movements are expected in infants up to 6 to 9 weeks corrected age. These movements are characterised by small to moderate amplitude and slow to moderate speed movements, which are elliptical in form. Abnormal GMs in the writhing period include poor repertoire, cramped synchronised and chaotic movements (Øberg, Jacobsen, & Jørgensen, 2015).
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Fidgety movements are expected in infants from 6 to 9 weeks corrected age to 20 weeks corrected age. These movements are characterised by small movements in all directions of moderate speed and variable acceleration in the neck, trunk and limbs. They are continuously present in an awake infant, except during focussed attention and crying. Abnormal fidgety movements are either absent if never observed or exaggerated with increased amplitude and jerkiness (Øberg et al., 2015).
Figure 31. Prechtl General Movements Assessment (Einspieler, Peharz, & Merschik, 2016)
Predictive Capacity
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GMs videoed around 3 months of age (ie. 12-16 weeks corrected age), provide most predictive information about the likely risk of CP (Cerebral Palsy Alliance, 2018b). According to Øberg et al. (2015), absence of fidgety movements in the fidgety period is strongly related to the diagnosis of CP by the age of 2 years with a sensitivity of ~90% in infants at high risk of motor impairment and those at low risk of motor impairment.
TREATMENT OPTIONS
Treatment for preterm infants and those who are not developing typically will vary depending on the deficits they present with. Treatment should always be play based to engage the infant and focus on enhancing expected developmental milestones and emerging abilities (Adolph & Franchak, 2018).
For More Information on Developmental Milestones and Age Appropriate Toys
RECOMMENDED REFERRALS
Early referral to a paediatrician should be completed when outcome measures used during physiotherapy assessments are indicative of increased risk of neurological conditions and/or developmental delay (Gullion et al., 2019).
Neurological conditions such as Cerebral Palsy are most commonly diagnosed after 18 months of age (Byrne, Noritz, & Maitre, 2017). Referrals to Early Childhood Early Intervention (ECEI) services should be completed prior to diagnosis if the infant presents with delays in multiple areas that are likely to be ongoing.