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Trauma in pregnancy and cerebral palsy: is there a link?

Marisa T Gilles, Eve Blair, Linda Watson, Nadia Badawi, Louisa Alessandri, Vivienne Dawes, Aileen J Plant and Fiona J Stanley
Med J Aust 1996; 164 (8): 500-501.
Published online: 15 April 1996
For Debate

Trauma in pregnancy and cerebral palsy: is there a link?

The link between maternal trauma during pregnancy and cerebral palsy remains to be proven

Marisa T Gilles, Eve Blair, Linda Watson, Nadia Badawi,
Louisa Alessandri, Vivienne Dawes, Aileen J Plant and Fiona J Stanley

MJA 1996; 164: 500-501

Introduction - Acknowledgements - References - Authors' details
- - Articles on similar material


Introduction Maternal trauma during pregnancy has been implicated in the aetiology of cerebral palsy in the surviving offspring.1,2 In 1991, a child with cerebral palsy received a settlement of three million dollars after it was alleged that the mother's negligent driving of a motor vehicle resulted in an accident which caused cerebral palsy in the child.1 The case rested on the testimony of an expert witness whose argument was based on a case series of six children with cerebral palsy born to mothers who had been involved in motor vehicle accidents. (Bergin AM, Stack JP, Stephenson JBP, King M. Cerebral palsy after motor accidents in pregnancy. Proceedings of the British Paediatric Neurology Association, Dublin, 1990 [unpublished data].) Possible mechanisms for the association between pregnancy trauma and cerebral palsy include reduced placental bloodflow, placental embolisation and placental abruption.

To address the

issue of trauma in pregnancy and subsequent cerebral palsy, we examined the Western Australian Cerebral Palsy Register3 (a subset of the Maternal and Child Health Research Database)4 which collects information on all children in the State who develop cerebral palsy (updated to the age of five years). We also examined the Hospital Morbidity Data System, which collects information on all acute hospital admissions. These two databases were selected in order to compare the rates of cerebral palsy in the offspring of women who, during their pregnancy, had trauma that required hospitalisation with the rates of cerebral palsy in the children of women who did not experience trauma. The Box outlines the methods and results of our study.

Despite the fact that this was a population-based study over 11 years (1982-1992), the unadjusted relative risk of having a child with cerebral palsy after exposure to trauma was 1.4 (95% confidence interval, 0.34-5.77), which was not statistically significant. It was inappropriate to adjust for gestational age or low birth weight as they may have been factors in the aetiological pathway (e.g., trauma may induce a premature birth).

Trauma occurs more commonly during the third trimester of pregnancy than at any other time in a woman's life.5 The incidence of trauma during pregnancy is reported to be about seven to eight per cent, but hospitalisation for trauma in pregnancy is rare. In the years of our study, only 0.3% of pregnant women were hospitalised. However, the severity of maternal trauma does not correlate well with the degree of fetal damage. Even minor trauma can cause fetal death and preterm labour,6-8 but few studies have considered the effect on long-term fetal outcome.2

Women who are not hospitalised (because of apparently minor trauma) may still have fetal compromise. In addition, women experiencing domestic violence may avoid medical attention, and hence such women may be under-represented in our study. Domestic violence during pregnancy, reported at rates between 8% and 17%, has been linked to fetal death, fetal distress and intrauterine growth retardation.9-11

The existence of one woman who was admitted to hospital for trauma at 28 weeks' gestation but had not been recorded as pregnant in the Hospital Morbidity Data System calls into question the validity of this data system in recording certain admission and discharge details relevant to our study. For example, in the presence of major trauma a pregnancy may be overlooked or not recorded, especially if the woman is in early pregnancy. This would lead to an underestimation of the number of women experiencing trauma during pregnancy who did not have a child with cerebral palsy, as only those women who were coded as being pregnant in the Hospital Morbidity Data System were included in the sample population.

Our study has not resolved whether major trauma during pregnancy is associated with long term neurological problems in the child. In view of increasing litigation in this area, larger analytical studies into the outcomes following physical trauma during pregnancy are needed. This will best be achieved when better mechanisms for recording details of trauma during pregnancy, including domestic violence, are developed.



Acknowledgements
This study would not have been possible without the financial support of Healthway and PHRDC, who fund the Cerebral Palsy Register; data provided by the Health Department of WA; the expertise of Dr Richard Hockey, who carried out the linkage; and the editorial support generously supplied by Dr Ian Rouse and Dr Jennifer Kurinczuk.


References
  1. Lynch v Lynch & Anor. Supreme Court of New South Wales (1991). Australian Tort Reports 81-117.
  2. Anquist KW, Parnes S, Cargill Y, Tawagi G. An unexpected fetal outcome following a severe maternal motor vehicle accident. Obstet Gynecol 1994; 84: 656-658.
  3. Stanley FJ, Watson L. Methodology of a cerebral palsy register. The Western Australian experience. Neuroepidemiology 1985; 4: 146-160.
  4. Stanley FJ, Croft ML, Gibbins J, Read AW. A population database for maternal and child health research in Western Australia using record linkage. Paediatr Perinat Epidemiol 1994; 8: 433-447.
  5. Patterson RM. Trauma in pregnancy. Clin Obstet Gynecol 1984; 27: 32-38.
  6. Williams JK, McClain L, Rosemurgy AS, Colorado NM. Evaluation of blunt abdominal trauma in the third trimester of pregnancy: Maternal and fetal considerations. Obstet Gynecol 1990; 75: 33-37.
  7. Farmer DL, Adzick S, Crombleholme WR, et al. Fetal trauma: relation to maternal injury. J Pediatr Surg 1990; 25: 711-714.
  8. Murdoch Eaton DG, Ahmed Y, Dubowitz LMS. Maternal trauma and cerebral lesions in preterm infants. Case reports. Br J Obstet Gynaecol 1991; 98: 1292-1294.
  9. Macfarlane J, Parker B, Soeken K, Bullock L. Assessing for abuse during pregnancy. Severity and frequency of injuries and associated entry into prenatal care. JAMA 1992; 267: 3176-3178.
  10. Dye TD, Tolliver NJ, Lee RV, Kenney CJ. Violence, pregnancy and birth outcome in Appalachia. Paediatr Perinat Epidemiol 1995; 9: 35-47.
  11. Webster J, Sweett S, Stolz TA. Domestic violence in pregnancy. A prevalence study. Med J Aust 1994; 161: 466-470.
  12. Stanley FJ, Watson L. Trends in perinatal mortality and cerebral palsy in Western Australia, 1967 to 1985. BMJ 1992; 304: 1658-1663.
  13. World Health Organization. International Classification of Diseases. 1975 revision, Vol 1. Geneva: Presses Centrales, 1977.
  14. Gee V. The 1991 Western Australian Birth Cohort. Statistical Series 34. Perth: Health Department of Western Australia, 1994: 5.


Authors' details Health Statistics Branch, Health Department of Western Australia, Perth, WA.
Marisa T Gilles, FAFPHM, Research Registrar; and Research Registrar, National Centre for Epidemiology and Population Health, Canberra.

TVW Telethon Institute for Child Health Research, Perth, WA.
Eve Blair, PhD, Senior Research Officer;
Linda Watson, Research Assistant;
Nadia Badawi, MSc, MRCPI, Paediatric Research Fellow;
Louisa Alessandri, BSc(Hons), PhD, Research Officer;
Fiona J Stanley, MD, FAFPHM, Professor of Paediatrics.

Department of Public Health, The University of Western Australia, Perth, WA.
Aileen J Plant, PhD, FAFPHM, Senior Lecturer.

Women's Cancer Screening Service, Health Department of Western Australia, Perth, WA.
Vivienne Dawes, FAFPHM, Medical Officer.

No reprints will be available.
Correspondence: Linda Watson, TVW Telethon Institute for Child Health Research, PO Box 855, West Perth, WA 6872.
E-mail: Linda@ichr.uwa.edu.au






Material trauma and cerebral palsy: a Western Australian population-based study, 1982-1992

Cerebral Palsy Register
The study population was extracted from the Cerebral Palsy Register, a data subset of the Maternal and Child Health Research Database, and consisted of mothers of all children with cerebral palsy born between 1982 and 1992 inclusive, excluding those children who had a documented postnatal cause of cerebral palsy. A year-of-birth cohort of the Cerebral Palsy Register is only considered complete at the age of five years. Thus, by including the years 1990 to 1992 it is possible that as yet unregistered cases of cerebral palsy may have been misclassified as not having cerebral palsy. However, because cerebral palsy is rare (approximately 2 per 1000 live births),12 the effect of this error is very small.

Hospital Morbidity Data System
The sample population comprised all women between the ages of 14 to 50 with an ICD-9 external cause of injury (excluding poisons, drugs and medical misadventure)13 and the additional code for pregnancy in the Hospital Morbidity Data System. To validate the Hospital Morbidity Data System, a second method of identifying cases was used. The period of pregnancy was defined as the time between the second postmenstrual week and delivery, and the dates defining this period were identified for each pregnancy that resulted in a child with cerebral palsy.

Database linkage
Data from the Cerebral Palsy Register were linked with the births file, another subset of the Maternal and Child Health Research Database, to obtain identifying data for each mother in the study group, such as surname, maiden name, date of birth and address at the time of delivery. Using these identifying data, mothers were linked to the Hospital Morbidity Data System to determine exposure to trauma requiring hospitalisation during pregnancy.

Statistical analysis
Data were analysed using two-by-two contingency tables, and the relative risk was calculated with 95% confidence intervals.

Results

  • 529 children were born with cerebral palsy between 1982 and 1992, inclusive (extracted from the Cerebral Palsy Register). (See Box.)
  • 770 pregnant women were hospitalised for trauma between 1982 and 1992 (extracted from the Hospital Morbidity Data System).
  • The details of two of the mothers hospitalised for trauma during their pregnancy matched the details of two mothers of children with cerebral palsy.
  • The incidence of cerebral palsy in children of women hospitalised for trauma during pregnancy was 2.6 per 1000 pregnant women.
  • The incidence of cerebral palsy in children of women who did not experience trauma requiring hospitalisation during their pregnancy was 1.8 per 1000 pregnant women.
  • A woman exposed to trauma requiring hospitalisation during pregnancy had 1.4 times the risk of having a child with cerebral palsy compared with a woman who had not had this experience (unadjusted relative risk, 1.4; 95% confidence interval, 0.34-5.77). The number of cases was small and this result was not statistically significant (Box).
  • One mother who had a child with cerebral palsy and had been hospitalised for trauma during pregnancy was not recorded as being pregnant on the Hospital Morbidity Data System. Inclusion of this case in the two-by-two analysis increased the relative risk to 2.2 (95% confidence interval, 0.66-6.69), but only those women coded as being pregnant in the Hospital Morbidity Data System were included in the sample population (see text).
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  • Marisa T Gilles
  • Eve Blair
  • Linda Watson
  • Nadia Badawi
  • Louisa Alessandri
  • Vivienne Dawes
  • Aileen J Plant
  • Fiona J Stanley


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