D e v c 4 p Med. Child Nerirof. 1975, 17, 3-17
Very Low Birthweight and Subsequent Neurological Defect (with special reference to spastic diplegia)
Pamela A . Davies J. P. M. Tizard
tend to differ in certain respects from those of spastic children born at term. Firstly, the spastic weakness affects the legs far n79~ethan the arms-indeed the arms may be spared altogether, giving the clinical picture of spastic paraplegia. Spasticity in the legs particularly involves the adductors of the thighs and the plantar flexors of the feet. It is usually bilaterally symmetrical, but by no means invariably so. Indeed, it seems likely that spastic monoplegia involving only one leg may have the same aetiological basis (McDonald 1964), although this distribution is very unusual. If motor disturbances in the upper extremities are detectable they usually take the form of clumsiness or tremor, or sometimes ataxia, and these signs tend to abate with the passage of time. Secondly, head size and intelligence are not usually as abnormally low as is the case in spastic children who have been born at term. Thirdly, fits are much less common. Freud (1893) states: “Little did not make any distinction between general rigidity and those cases in which the disease affected the lower extremities, mainly or exclusively“. This is true, although Little (1862) would have been justified in so
Spastic Diplegia (or Paraplegia) of Very Low Birthweight Many attempts have been made to classify the ‘cerebral palsies’ on the basis of clinical findings. However, since pathological processes affecting the brain may well not respect functional boundaries-if indeed these exist-it is not surprising that a rigid delineation of types of cerebral palsy has proved to be very difficult. In the battle between the ‘splitters’ and the ‘lumpers’ (to use-in another contextDr. Victor McKusick’s picturesque phrase), the former once held sway; but so absurdly lengthy and complex were the subdivisions of types of cerebral palsy (Phelps 1949) that the lumpers have taken over. Cerebral diplegia (a term invented by Sigmund Freud) is now often considered synonymous with spastic tetraplegia or quadriplegia (Crothers and Paine 1959, lngram 1964). However, there does seem to be some justification for separating from this collection of conditions of differing aetiologies and clinical effects a group of spastic children who have one thing in commonnamely very low birthweight. The clinical findings in these children who have also been of short gestation do
i
Repritir wque.sts l o :
-
Dr. Pamela A . Davies, Institute of Child Health. Hammersmith Hospital, London
w12.
3
1975, 17
DEVELOPMENTAL MEDICINE A N D CHILD NEUROLOGY.
TABLE I Data derived from Little (1862) pp. 318-333 Maiuriiy
‘Rigidity’ confined to legs* Rigidity also involving one or bolh arms
Term Pre-term Total Term Pre-term Total
3 21 24** 20 3 23
Abtiornial di4ivery?.
3 6 9
~
20 2 22
* Apart from the ‘clumsiness’ of the hands in some cases.
** This agrees with Osler’s ( I
889) estimate of the numbers of paraplegic cases in Little’s
series. t Includes birth asphyxia
doing from an additional analysis of his 47 cases of ‘Spastic Rigidity-Labour Abnormal or Premature or Asphyxia at Birth’. In the text of his paper, Little states: “sometimes the upper extremities appear unaffected with spasm or want of volition, sometimes a mere awkwardness in using them”. Not all Little’s case histories are complete, but Table I shows the relationship between the distribution of the ‘rigidity’, pre-term and term birth, and normal or abnormal delivery as far as can be ascertained from the information he provides. It seems clear that ‘rigidity’ involving the legs only was generally associated with pre-term (but otherwise normal) delivery, whereas ‘rigidity’ involving all four limbs was associated with abnormal delivery at term. Thus many authors (including Freud) have described diplegia of short gestation as ‘infantile cerebral paraplegia’. A further reason for separating this type from other types of diplegia is that several authors have shown that the birthweights of children with bilateral spasticity are bimodally distributed, and that the birthweight distribution of cases of cerebral paraplegia is well to the left of those of other forms of cerebral palsy (Evans 1948, Childs and Evans 1954, Eastman and DeLeon 1955, Churchill 1958).
A final reason for considering spastic diplegia of very short gestation as a separate entity is that in recent years its incidence has shown a greater decline than that of other forms of cerebral palsy (Hagberg et a/. 1973), suggesting that it has a separate aetiological basis. All in all there seems to be valid reasons for accepting Freud’s conclusion: “In the discussion of the relationships between Little’s factors and individual types of diplegias, one has to separate premature birth from all other birth anomalies. There is a specific relationship between premature birth and paraplegic rigidity on one hand and between difficult birth (which includes all other factors) and general rigidity on the other hand”. “Yet it should be added that these relationships are in no way exclusive ones.” The likelihood of spastic diplegia has been inversely correlated with length of gestation (McDonald 1967). Illingworth (1968) considered it probable that infants weighing less than 900g at birth would have a 50 per cent chance of being affected. The incidence of cerebral diplegia in several of the larger follow-up studies of very lowbirthweight babies is shown in Table 11. The aetiology, other than the common denominator of immaturity, has been widely discussed, but never settled.
4
PAMELA A. DAVIES
1. P. M. TlZAHO
%
Saniple -
~
Luhchenco P f NI. ( 1972)
Birth wcin.lit
Y l w of birth
Arrthors -~~ -
~
--
Drillien (1964)
1947- I950 1948- I960
McDonald (1967) Wright c’t a / . ( 1972)
1951-1953 1952-1 9.56
Davics and Tizard (1975) Davics and Tizard (1975)
I961 -1964 1965- I970
The Declining Incidence of Diplegia of Pre-term Birth Woods (1963) reported a lower incidence of infantile cerebral palsy in Bristol in the years 1953-62, compared with 1943-53. Separate figures for the various types of cerebral palsy were not given and i t was not clear to what extent spastic diplegia shared i n this fall. This article provoked a lively correspondence but the consensus was that, elsewhere at least, a falling incidence o f cerebral palsy was n o t proven. The matter was raised again by Brandt et ul. (1965) in Denmark, but the differences in case finding and reporting made a definite conclusion impossible, and in any event spastic diplegia did not appear to share in the decrease. In 1970 an actual increase in the proportion o f patients with spastic diplegia attending cerebral palsy clinics was reported by Masland (1970) from the United States. He was uncertain whether this was due to increased survival of infants of short gestation o r to a reduction in other forms of cerebral palsy, particularly the athetoid variety associated with liyperbilirubinaemia, which for some years had been a preventable disease. However, Hagberg rjt ul. (1973) made a complete assessment of cases from one well-defined Swedish region with an uniform evaluation and classification of cerebral palsy syndromes. They showed a decreasing incidence of cerebral diplegia in low-birthweight infants in the years 196468 compared with 199-63. We wish to
-
~~
b’15oog I36Og . .1580g *>
15OGg
‘: 1500g
I5oog
ii/iinb~r
Spastic diphgia ( ‘’0)
__--.
I33 91 560 65 58 137
_--___
32 20 7 9
10
0
record a similar decreased incidence in recent years and to discuss some of he possible contributory f.dctors. Patients and Methods During the years 1961-70 inclusive, 70 patients weighing l5OOg or less and surviving the first week of life were either born i n o r admitted shortly after birth to Hammersmith Hospital. There were two major changes i n neonatal care during the period under review : ( I ) an increased food intake in the first week of life from 1965 onwards. and ( 2 ) a greater awareness (also in the latter years) of the need to maintain body temperature in the thermo-neutral range. The infants have been divided therefore into those born in the two periods I961 -64 and 1965-70 for purposes o f comparison, and the differences in food intake and body temperature are shown in Table 111. Details of the food given and site of temperature recording have becn given elsewhere (Davies and Davis 1970), as have other details of their neonatal care (Davies ct ul. 1972). Five of the 170 infants died before the age of six months. one in the earlier period and four in the later period. Three children who were thought to be developing normally died suddenly and unexpectedly at home, two at the ages of three months and one at four month-an example of the lamentably high rate of ‘cot deaths’ in survivors of very low birthweight. One of these deaths took place in the earlier
DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY.
1975, 17
period (1961-64). A fourth child died shortly after re-admission with gastroenteritis at four months; this infant had hydrocephalus, presumed to be secondary to neonatal intraventricular haemorrhage. A fifth infant died at two months following an operation elsewhere for intestinal obstruction. These five have been excluded from the analysis, which thus deals with 165 children. We extracted the following information from the case notes: Matertial data: age, height, previous infertility, previous miscarriage, threatened miscarriage, antepartum haemorrhage, toxaemia, hypertension, duration of first and second stages of labour, fetal distress, mode of delivery and episiotomy. Infant data: birthweight, gestation, sex, social class, birthplace (Hammersmith or elsewhere), multiple pregnancy, fetal distress, birth asphyxia (with and without endotracheal intubation), respiratory distress, recurrent apnoea*, fits, hypoglycaemia (asymptomatic and symptomatic), maximum serum bilirubin, functional intestinal obstruction, proven infection, antibiotic therapy, duration of oxygen therapy, maximum percentage weight loss, time birthweight regained, mean lowest rectal temperature, mean daily
rectal temperature (see Table III), mean milk intake (see Table 111). After discharge from the nursery, followup examinations were made in the outpatient clinic at approximately threemonthly intervals during the first year, and then less often depending on need. Details of illness and developmental achievements were recorded; weight and head circumference, and length or standing height were measured, and a careful clinical examination made which included items of developmental testing (Sheridan 1960, Frankenburg and Dodds 1967). Ophthalmological examination and assessment of hearing were done by Mr. A. S . Mushn and Mr. H. A. Beagley respectively in many children as a routine, but in all those in whom there was a suspicion of visual or hearing defects at general clinical examination. Although a sizeable proportion of the children now live elsewhere, the majority are seen occasionally, and with one exception (a child born in 1962), contact has been maintained with all directly and/ or with their family doctor or the local paediatrician. The results of follow-up examination and details of growth were incorporated with the perinatal data and stored on magnetic tape.
* Apnoea was defined as cessation of breathing
Abnormalities at Follow-up Visual Four children are partially sighted, two born 1961-64 (3.4 per cent) and two born
for 2 2 0 seconds: mild apnoea, that which responded to stimulation alone: severe apnoea, that for which positive pressure ventilation was required.
TABLE 111 Food intake and body temperature in the first month
I
I
Mean intake (ccikg birthweight) 1961-64 1965-70 Mean temperatiire ('C) 1961-64 1965-70
t
'
'
DA Y
1
2
3
4
12* 51
32* 81
53* 103
73* 126
7
14
21
28
129* 156
188
196
209 220
230 240
36.1* 36.4
36.1* 36.5
36.2t 36.4
35.0* 35.7* 35.9* 35.8* 35.9* 36.1 36.4 36.3 36.4 36.6
p = 0.005.
6
PAMELA A. DAVIES
J. P. M . TIZAKD
children has spastic quadriplegia and is mentally retarded; she was small for dates and had symptomatic hypoglycaemia. The remaining six children have spastic diplegia of pre-term birth.
1965-70 (1.9 per cent). One child born in the earlier period has cataracts; the other three have retrolental fibroplasia. Lesser degrees of myopia and squint will be given in a separate report. Anterior lens opacities not interfering with vision are present in two other children born in the later period.
Other Neurological Abnormulity
Seven children, two born in the period 1961-64 (3.4 per cent) and five born in the period 1965-70 (4.7 per cent), have minor handicaps of gait or co-ordination. In one, born in 1969, the abnormality of gait is associated with myelomeningocele which was treated surgically in the neonatal period. Of the remaining six, four were slow to walk, had unsteady wide-based gaits as infants and have never become elegant walkers or potential athletes. Two of these and two others were considered to be clumsy with their hands. However, in none of these six cases has there been any sign of spasticity.
Heuring Five children, two born 1961-64 (3.4 per cent) and three born 1965-70 (2.8 per cent), have varying degrees of deafness. In two (both born in the later period) it is severe and due to congenital rubella. In the two children born in the earlier period, deafness is due to hyperbilirubinaemia and middle-ear disease respectively. In the remaining child no known cause of deafness has been identified. Ititelligetm Of the 120 children born during the entire period 1961-68, 105 have been tested. Results are reported separately (FrancisWilliams and Davies 1974).
Results of Analyses We analysed maternal and infant data in two ways: firstly we compared all the surviving babies born 1961-64 with those born 1965-70; and secondly, we compared the six diplegic babies born 1961-64 with the remaining 52 born in the same period. Significant differences between 1961-64 and 1965-70 are listed in Tables I11 and IV. There was only one significant differ-
Cerebral Palsy Seven of the children have cerebral palsy and all were born in the 1961-64 period. When compared with the period 1956-70, this difference is highly significant (x2 = 10.68, p = 0.0011). One of these
TABLE 1V
Significant differences between surviving babies of
I Total Born outside Hammersmith Hospital Birth asphyxia (intubated) Fits Symptomatic hypoglycaemia Mild recurrent apnoea Mean maximum bilirubin (nig) Mean lowest rectal temperature ('C) I
Very Low Birthweight and Subsequent Neurological Defect (with special reference to spastic diplegia)
Pamela A . Davies J. P. M. Tizard
tend to differ in certain respects from those of spastic children born at term. Firstly, the spastic weakness affects the legs far n79~ethan the arms-indeed the arms may be spared altogether, giving the clinical picture of spastic paraplegia. Spasticity in the legs particularly involves the adductors of the thighs and the plantar flexors of the feet. It is usually bilaterally symmetrical, but by no means invariably so. Indeed, it seems likely that spastic monoplegia involving only one leg may have the same aetiological basis (McDonald 1964), although this distribution is very unusual. If motor disturbances in the upper extremities are detectable they usually take the form of clumsiness or tremor, or sometimes ataxia, and these signs tend to abate with the passage of time. Secondly, head size and intelligence are not usually as abnormally low as is the case in spastic children who have been born at term. Thirdly, fits are much less common. Freud (1893) states: “Little did not make any distinction between general rigidity and those cases in which the disease affected the lower extremities, mainly or exclusively“. This is true, although Little (1862) would have been justified in so
Spastic Diplegia (or Paraplegia) of Very Low Birthweight Many attempts have been made to classify the ‘cerebral palsies’ on the basis of clinical findings. However, since pathological processes affecting the brain may well not respect functional boundaries-if indeed these exist-it is not surprising that a rigid delineation of types of cerebral palsy has proved to be very difficult. In the battle between the ‘splitters’ and the ‘lumpers’ (to use-in another contextDr. Victor McKusick’s picturesque phrase), the former once held sway; but so absurdly lengthy and complex were the subdivisions of types of cerebral palsy (Phelps 1949) that the lumpers have taken over. Cerebral diplegia (a term invented by Sigmund Freud) is now often considered synonymous with spastic tetraplegia or quadriplegia (Crothers and Paine 1959, lngram 1964). However, there does seem to be some justification for separating from this collection of conditions of differing aetiologies and clinical effects a group of spastic children who have one thing in commonnamely very low birthweight. The clinical findings in these children who have also been of short gestation do
i
Repritir wque.sts l o :
-
Dr. Pamela A . Davies, Institute of Child Health. Hammersmith Hospital, London
w12.
3
1975, 17
DEVELOPMENTAL MEDICINE A N D CHILD NEUROLOGY.
TABLE I Data derived from Little (1862) pp. 318-333 Maiuriiy
‘Rigidity’ confined to legs* Rigidity also involving one or bolh arms
Term Pre-term Total Term Pre-term Total
3 21 24** 20 3 23
Abtiornial di4ivery?.
3 6 9
~
20 2 22
* Apart from the ‘clumsiness’ of the hands in some cases.
** This agrees with Osler’s ( I
889) estimate of the numbers of paraplegic cases in Little’s
series. t Includes birth asphyxia
doing from an additional analysis of his 47 cases of ‘Spastic Rigidity-Labour Abnormal or Premature or Asphyxia at Birth’. In the text of his paper, Little states: “sometimes the upper extremities appear unaffected with spasm or want of volition, sometimes a mere awkwardness in using them”. Not all Little’s case histories are complete, but Table I shows the relationship between the distribution of the ‘rigidity’, pre-term and term birth, and normal or abnormal delivery as far as can be ascertained from the information he provides. It seems clear that ‘rigidity’ involving the legs only was generally associated with pre-term (but otherwise normal) delivery, whereas ‘rigidity’ involving all four limbs was associated with abnormal delivery at term. Thus many authors (including Freud) have described diplegia of short gestation as ‘infantile cerebral paraplegia’. A further reason for separating this type from other types of diplegia is that several authors have shown that the birthweights of children with bilateral spasticity are bimodally distributed, and that the birthweight distribution of cases of cerebral paraplegia is well to the left of those of other forms of cerebral palsy (Evans 1948, Childs and Evans 1954, Eastman and DeLeon 1955, Churchill 1958).
A final reason for considering spastic diplegia of very short gestation as a separate entity is that in recent years its incidence has shown a greater decline than that of other forms of cerebral palsy (Hagberg et a/. 1973), suggesting that it has a separate aetiological basis. All in all there seems to be valid reasons for accepting Freud’s conclusion: “In the discussion of the relationships between Little’s factors and individual types of diplegias, one has to separate premature birth from all other birth anomalies. There is a specific relationship between premature birth and paraplegic rigidity on one hand and between difficult birth (which includes all other factors) and general rigidity on the other hand”. “Yet it should be added that these relationships are in no way exclusive ones.” The likelihood of spastic diplegia has been inversely correlated with length of gestation (McDonald 1967). Illingworth (1968) considered it probable that infants weighing less than 900g at birth would have a 50 per cent chance of being affected. The incidence of cerebral diplegia in several of the larger follow-up studies of very lowbirthweight babies is shown in Table 11. The aetiology, other than the common denominator of immaturity, has been widely discussed, but never settled.
4
PAMELA A. DAVIES
1. P. M. TlZAHO
%
Saniple -
~
Luhchenco P f NI. ( 1972)
Birth wcin.lit
Y l w of birth
Arrthors -~~ -
~
--
Drillien (1964)
1947- I950 1948- I960
McDonald (1967) Wright c’t a / . ( 1972)
1951-1953 1952-1 9.56
Davics and Tizard (1975) Davics and Tizard (1975)
I961 -1964 1965- I970
The Declining Incidence of Diplegia of Pre-term Birth Woods (1963) reported a lower incidence of infantile cerebral palsy in Bristol in the years 1953-62, compared with 1943-53. Separate figures for the various types of cerebral palsy were not given and i t was not clear to what extent spastic diplegia shared i n this fall. This article provoked a lively correspondence but the consensus was that, elsewhere at least, a falling incidence o f cerebral palsy was n o t proven. The matter was raised again by Brandt et ul. (1965) in Denmark, but the differences in case finding and reporting made a definite conclusion impossible, and in any event spastic diplegia did not appear to share in the decrease. In 1970 an actual increase in the proportion o f patients with spastic diplegia attending cerebral palsy clinics was reported by Masland (1970) from the United States. He was uncertain whether this was due to increased survival of infants of short gestation o r to a reduction in other forms of cerebral palsy, particularly the athetoid variety associated with liyperbilirubinaemia, which for some years had been a preventable disease. However, Hagberg rjt ul. (1973) made a complete assessment of cases from one well-defined Swedish region with an uniform evaluation and classification of cerebral palsy syndromes. They showed a decreasing incidence of cerebral diplegia in low-birthweight infants in the years 196468 compared with 199-63. We wish to
-
~~
b’15oog I36Og . .1580g *>
15OGg
‘: 1500g
I5oog
ii/iinb~r
Spastic diphgia ( ‘’0)
__--.
I33 91 560 65 58 137
_--___
32 20 7 9
10
0
record a similar decreased incidence in recent years and to discuss some of he possible contributory f.dctors. Patients and Methods During the years 1961-70 inclusive, 70 patients weighing l5OOg or less and surviving the first week of life were either born i n o r admitted shortly after birth to Hammersmith Hospital. There were two major changes i n neonatal care during the period under review : ( I ) an increased food intake in the first week of life from 1965 onwards. and ( 2 ) a greater awareness (also in the latter years) of the need to maintain body temperature in the thermo-neutral range. The infants have been divided therefore into those born in the two periods I961 -64 and 1965-70 for purposes o f comparison, and the differences in food intake and body temperature are shown in Table 111. Details of the food given and site of temperature recording have becn given elsewhere (Davies and Davis 1970), as have other details of their neonatal care (Davies ct ul. 1972). Five of the 170 infants died before the age of six months. one in the earlier period and four in the later period. Three children who were thought to be developing normally died suddenly and unexpectedly at home, two at the ages of three months and one at four month-an example of the lamentably high rate of ‘cot deaths’ in survivors of very low birthweight. One of these deaths took place in the earlier
DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY.
1975, 17
period (1961-64). A fourth child died shortly after re-admission with gastroenteritis at four months; this infant had hydrocephalus, presumed to be secondary to neonatal intraventricular haemorrhage. A fifth infant died at two months following an operation elsewhere for intestinal obstruction. These five have been excluded from the analysis, which thus deals with 165 children. We extracted the following information from the case notes: Matertial data: age, height, previous infertility, previous miscarriage, threatened miscarriage, antepartum haemorrhage, toxaemia, hypertension, duration of first and second stages of labour, fetal distress, mode of delivery and episiotomy. Infant data: birthweight, gestation, sex, social class, birthplace (Hammersmith or elsewhere), multiple pregnancy, fetal distress, birth asphyxia (with and without endotracheal intubation), respiratory distress, recurrent apnoea*, fits, hypoglycaemia (asymptomatic and symptomatic), maximum serum bilirubin, functional intestinal obstruction, proven infection, antibiotic therapy, duration of oxygen therapy, maximum percentage weight loss, time birthweight regained, mean lowest rectal temperature, mean daily
rectal temperature (see Table III), mean milk intake (see Table 111). After discharge from the nursery, followup examinations were made in the outpatient clinic at approximately threemonthly intervals during the first year, and then less often depending on need. Details of illness and developmental achievements were recorded; weight and head circumference, and length or standing height were measured, and a careful clinical examination made which included items of developmental testing (Sheridan 1960, Frankenburg and Dodds 1967). Ophthalmological examination and assessment of hearing were done by Mr. A. S . Mushn and Mr. H. A. Beagley respectively in many children as a routine, but in all those in whom there was a suspicion of visual or hearing defects at general clinical examination. Although a sizeable proportion of the children now live elsewhere, the majority are seen occasionally, and with one exception (a child born in 1962), contact has been maintained with all directly and/ or with their family doctor or the local paediatrician. The results of follow-up examination and details of growth were incorporated with the perinatal data and stored on magnetic tape.
* Apnoea was defined as cessation of breathing
Abnormalities at Follow-up Visual Four children are partially sighted, two born 1961-64 (3.4 per cent) and two born
for 2 2 0 seconds: mild apnoea, that which responded to stimulation alone: severe apnoea, that for which positive pressure ventilation was required.
TABLE 111 Food intake and body temperature in the first month
I
I
Mean intake (ccikg birthweight) 1961-64 1965-70 Mean temperatiire ('C) 1961-64 1965-70
t
'
'
DA Y
1
2
3
4
12* 51
32* 81
53* 103
73* 126
7
14
21
28
129* 156
188
196
209 220
230 240
36.1* 36.4
36.1* 36.5
36.2t 36.4
35.0* 35.7* 35.9* 35.8* 35.9* 36.1 36.4 36.3 36.4 36.6
p = 0.005.
6
PAMELA A. DAVIES
J. P. M . TIZAKD
children has spastic quadriplegia and is mentally retarded; she was small for dates and had symptomatic hypoglycaemia. The remaining six children have spastic diplegia of pre-term birth.
1965-70 (1.9 per cent). One child born in the earlier period has cataracts; the other three have retrolental fibroplasia. Lesser degrees of myopia and squint will be given in a separate report. Anterior lens opacities not interfering with vision are present in two other children born in the later period.
Other Neurological Abnormulity
Seven children, two born in the period 1961-64 (3.4 per cent) and five born in the period 1965-70 (4.7 per cent), have minor handicaps of gait or co-ordination. In one, born in 1969, the abnormality of gait is associated with myelomeningocele which was treated surgically in the neonatal period. Of the remaining six, four were slow to walk, had unsteady wide-based gaits as infants and have never become elegant walkers or potential athletes. Two of these and two others were considered to be clumsy with their hands. However, in none of these six cases has there been any sign of spasticity.
Heuring Five children, two born 1961-64 (3.4 per cent) and three born 1965-70 (2.8 per cent), have varying degrees of deafness. In two (both born in the later period) it is severe and due to congenital rubella. In the two children born in the earlier period, deafness is due to hyperbilirubinaemia and middle-ear disease respectively. In the remaining child no known cause of deafness has been identified. Ititelligetm Of the 120 children born during the entire period 1961-68, 105 have been tested. Results are reported separately (FrancisWilliams and Davies 1974).
Results of Analyses We analysed maternal and infant data in two ways: firstly we compared all the surviving babies born 1961-64 with those born 1965-70; and secondly, we compared the six diplegic babies born 1961-64 with the remaining 52 born in the same period. Significant differences between 1961-64 and 1965-70 are listed in Tables I11 and IV. There was only one significant differ-
Cerebral Palsy Seven of the children have cerebral palsy and all were born in the 1961-64 period. When compared with the period 1956-70, this difference is highly significant (x2 = 10.68, p = 0.0011). One of these
TABLE 1V
Significant differences between surviving babies of
I Total Born outside Hammersmith Hospital Birth asphyxia (intubated) Fits Symptomatic hypoglycaemia Mild recurrent apnoea Mean maximum bilirubin (nig) Mean lowest rectal temperature ('C) I
