Atmospheric pollutants and mortalities in English local authority areas.

OBJECTIVES: To measure geographical co-relationships between disease-specific standardised mortality ratios (SMR) and different atmospheric emissions in 352 English local authorities. To link specific exposures with specific causes of death and to identify responsible polluting sources. To see whether long-term moderate exposures have the same lethal effects as short-term high-pollution (ie, smog) episodes. DESIGN: Geographical distributions of SMR, atmospheric emissions and social hazards, extracted from three different sources, were converted to a congruent format. Correlation coefficients were calculated within and between these different datasets. Mortality/pollutant correlations were recalculated after additionally standardising the SMR for social differences between local authorities. SETTING: The 352 English local authority areas, 1996-2004. MAIN RESULTS: SMR for one group of diseases (including upper alimentary and respiratory cancers, ischaemic heart disease, peptic ulcer, pneumonia) were related to a range of combustion emissions and to multiple social deprivation, cigarette smoking, binge drinking and a northern location. Additional standardisation of all SMR for these social hazards left a small subgroup independently related to atmospheric pollution, mainly from oil combustion. Correlations with pneumonia deaths were exceptional. CONCLUSIONS: High mortality rates were observed in areas with elevated ambient pollution levels. The strongest single effect was an increase in pneumonia deaths. Road transport was the chief source of the emissions responsible, although it was not possible to discriminate between the different chemical components. Many "pneumonia" deaths were probably caused by direct chemical injury, as in the 1952 London smog and are better regarded as "acute respiratory distress syndrome" or "acute lung injury".

Roads, railways, and childhood cancers.

STUDY OBJECTIVES: To locate geographical sources of engine exhaust emissions in Great Britain and to link them with the birth addresses of children dying from cancer. To estimate the cancer initiating roles of nearby roads and railways and to measure effective ranges. DESIGN: Birth and death addresses of all children born between 1955 and 1980 in Great Britain, and dying from leukaemia or other cancer during those years, were linked to locations of railway stations, bus stations, ferry terminals, railways, roads, canals, and rivers. Nearest distances to births and deaths were measured, and migration data relating to children who had moved house were analysed. Excesses of close to hazard birth addresses, compared with close to hazard death addresses, indicate a high prenatal or early postnatal risk of cancer initiation. SETTING AND SUBJECTS: Child cancer birth and death addresses and their map references were extracted from an earlier inquiry. Map references of putative hazards were downloaded from the Ordnance Survey national digital map of Great Britain. These data are recorded to a precision of one metre and have ground accuracies around 20 metres. MAIN RESULTS: Significant birth excesses were found within short distances of bus stations, railway stations, ferries, railways, and A,B class roads, with a relative risk of 2.1 within 100 m, tapering to neutral after 3.0 km. About 24% of child cancers were attributable to these joint birth proximities. Roads exerted the major effect. CONCLUSIONS: Child cancer initiations are strongly determined by prenatal or early postnatal exposures to engine exhaust gases, probably through maternal inhalation and accumulation of carcinogens over many months. The main active substance is probably 1,3-butadiene.

Oil combustion and childhood cancers.

STUDY OBJECTIVES: To identify specific toxic atmospheric emissions and their industrial sources in Great Britain. To link them with each other and with the birth addresses of children dying from cancer. To identify specific causal agents and sources. DESIGN: Birth and death addresses of children dying from cancer were linked to emissions hotspots for specific chemicals: and to related source installations. Among those who moved house, distances from each address to the nearest hazard were compared. Relative excesses of close-to-hazard birth addresses showed high prenatal or early postnatal risks. Relative risks for individual and for combined exposures were measured. SETTING AND SUBJECTS: Atmospheric emissions hotspots (UK, 2001) published as maps on the internet, were converted to coordinates. Industrial sites were identified through trade directories and map inspections. Child cancer addresses for 1955-80 births were extracted from an earlier inquiry and their postcodes converted to map references. MAIN RESULTS: There were excess relative risks (RR) within 0.3 km of hotspots for carbon monoxide, PM10 particles, nitrogen oxides, 1,3-butadiene, benzene, dioxins, benzo(a)pyrene, and volatiles; and within 1.0 km of bus stations, hospitals, heavy transport centres, railways, and oil installations. Some excesses were attributable to mutual confounding, but 1,3-butadiene and carbon monoxide, mainly derived from engine exhausts, were powerful independent predictors. They were strongly reinforced when associated with bus stations, hospitals, railways, oil installations, and industrial transport centres; RR = 12.6 for joint <0.5 km exposure to bus stations and 1,3-butadiene. CONCLUSIONS: Childhood cancers are strongly determined by prenatal or early postnatal exposures to oil based combustion gases, especially from engine exhausts. 1,3-butadiene, a known carcinogen, may be directly causal.

Childhood cancers and atmospheric carcinogens.

STUDY OBJECTIVES: To retest previous findings that childhood cancers are probably initiated by prenatal exposures to combustion process gases and to volatile organic compounds (VOCs); and to identify specific chemical hazards. DESIGN: Birth and death addresses of fatal child cancers in Great Britain between 1966 and 1980, were linked with high local atmospheric emissions of different chemical species. Among migrant children, distances from each address to the nearest emissions "hotspot" were compared. Excesses of outward over inward migrations show an increased prenatal or early infancy risk. SETTING AND SUBJECTS: Maps of emissions of many different substances were published on the internet by the National Atmospheric Emissions Inventory and "hotspots" for 2001 were translated to map coordinates. Child cancer addresses were extracted from an earlier inquiry into the carcinogenic effects of obstetric radiographs; and their postcodes translated to map references. MAIN RESULTS: Significant birth proximity relative risks were found within 1.0 km of hotspots for carbon monoxide, PM10 particles, VOCs, nitrogen oxides, benzene, dioxins, 1,3-butadiene, and benz(a)pyrene. Calculated attributable risks showed that most child cancers and leukaemias are probably initiated by such exposures. CONCLUSIONS: Reported associations of cancer birth places with sites of industrial combustion, VOCs uses, and associated engine exhausts, are confirmed. Newly identified specific hazards include the known carcinogens 1,3-butadiene, dioxins, and benz(a)pyrene. The mother probably inhales these or related materials and passes them to the fetus across the placenta.

An epidemic pattern of murder.

The dates and places of 105 suspected or proven murders committed by Dr H. Shipman of Hyde in Greater Manchester between 1984 and 1998 were subjected to epidemiological analysis. These interim data were assembled through a variety of media sources and were based upon court proceedings and police investigations. The analysis revealed a significant excess of case pairs separated jointly by distances <0.6 km and by times <7 days. These sequences were also associated with purely geographical groupings within spatial diameters <0.2 km, but with longer time intervals. This was confirmed by an extended analysis of case triplets occurring within short times and distances. They showed a significant excess. These clusters were probably generated by a combination of psychopathic obsession, of local opportunity, and of caution; and in similar circumstances could occur again. The findings demand the regular display of mortality data in a format permitting the intuitive recognition of similar phenomena elsewhere.

Effects at age nine of maternal smoking in pregnancy: experimental and observational findings.

OBJECTIVES: To compare long term outcomes of a randomised controlled trial of anti-smoking education in pregnancy and to examine the same outcomes according to maternal pregnancy smoking behaviour. DESIGN: Follow up of the population included in the randomised controlled trial nine years later and of ex-smokers and non-smokers within the same hospital population. SETTING: A maternity hospital in Birmingham with follow up of children in schools and mothers at home. POPULATION: 1218 smokers recruited to the trial; also 191 ex-smokers at booking and 414 non-smokers throughout pregnancy. METHODS: Children were assessed individually by psychologists in schools, and mothers interviewed at home to obtain additional information relevant to cognitive development and growth. Information on smoking during pregnancy was obtained from mothers and obstetric data from computerised case-notes, both recorded immediately following delivery. MAIN OUTCOME MEASURES: Height, weight, IQ and neurological soft signs at 9.4 years. RESULTS: Differences in birthweight and length between the intervention and control groups were confirmed but no intervention-control differences were found at age 9.4 for weight, height, IQ or neurological soft signs. Differences were found for height and IQ according to mothers pregnancy smoking behaviour, but smoking did not remain an independent predictor after taking account of confounding factors. Alternative classifications of smoking behaviour, taking account of the gestation at stopping and mean cigarette consumption throughout pregnancy likewise showed no effect. CONCLUSIONS: The well established early hazards of smoking during pregnancy seem to be resolved by later childhood, with no evidence of direct long term effects on growth or cognitive functioning.

Geographical distribution of birth places of children with cancer in the UK.

Using birth addresses, we examined the geographical variation in risk for all types of childhood cancers in the UK, on a scale corresponding to the 10-km squares of the National Grid. The effects of socioeconomic and environmental factors, including natural background radiation, were investigated and their relative importance assessed using Poisson regression. Data came from a national collection of all fatal cancers between 1953 and 1980 in children aged 0-15 years and consisted of 9363 children of known place of birth from 12 complete annual cohorts born in the period 1953-64. For solid cancers, as well as for leukaemias and lymphomas, there was marked variation of cumulative mortality according to place of birth. High mortalities were associated with areas characterized as having high social class, higher incomes and good housing conditions, but also with high population densities (births per hectare). Each of these contrasting social indicators operated independently of the other, indicating complex determining mechanisms. Mortalities increased with increased radon exposure, and the relationship operated independently of the socioeconomic factors. At this scale of analysis, we found no increased mortality in industrialized areas. A population-mixing infective hypothesis, which postulates high rates of leukaemia when highly exposed urban populations are introduced to isolated rural areas, was supported by observations of high mortalities in 'growth areas' and New Towns, but was not readily reconcilable with the high rates seen in the high-density areas. If these correlations do indeed represent an infective mechanism, then the outcomes are not limited to malignancies of the immune system alone.

Migration patterns of children with cancer in Britain.

OBJECTIVES: To investigate the early migration patterns of children who later developed cancer. To test a prior hypothesis that some cancers are initiated by early exposures to toxic atmospheric pollutants from point sources. DESIGN: Address changes in children dying from cancer are examined in relation to potentially hazardous sites of several different types. The relative proximities of birth addresses and death addresses to these sites, are compared. The approach is based upon the premise that a local exposure, effective only at an early age, must be preferentially linked with an early address. SETTING AND SUBJECTS: Records of 22,458 children dying from leukaemia or other cancer under the age of 16 years in Great Britain between 1953 and 1980: including 9224 who moved house between birth and death. The migration analysis was based upon birth and death addresses, converted first to postcodes and thence to map coordinates. The geographical locations of potentially toxic industrial sites were obtained through direct map searches and from commercial directories. RESULTS: Systematic asymmetries were found between measured distances from birth and death addresses to sources emitting volatile organic compounds, or using large scale combustion processes. The children had more often moved away from these hazards than towards them. Many of the sources had already been identified as hazardous using other methods. There was also a birth association with areas of dense habitation; possibly because of unidentified toxic sources contained within them. All forms of cancer were involved although some effluents were associated preferentially with specific types. CONCLUSIONS: The main findings of an earlier study, based upon a different and independent method, were confirmed. Proximities to several types of industrial source, around the time of birth, were followed by a raised risk of childhood cancer. Combustion products and volatile organic compounds were especially implicated. Within the 16 year limit of the study, the increased risk did not decay with advancing age. Low atmospheric concentrations of many carcinogenic substances suggest that the mother acts as a cumulative filter and passes them to the fetus across the placenta or in breast milk.

Hazard proximities of childhood cancers in Great Britain from 1953-80.

STUDY OBJECTIVES: Firstly, to examine relationships between the birth and death addresses of children dying from leukaemia and cancer in Great Britain, and the sites of potential environmental hazards; and secondly to measure relative case densities close to, and at increasing distances from, different hazard types. DESIGN: Home address postcodes (PCs) and their map coordinates were identified at birth and at death in children who died from leukaemia or cancer. Potentially hazardous industrial addresses and PCs were listed from business and other directories, and map coordinates obtained from the Central Postcode Directory or else located directly on Ordnance Survey (OS) maps. Railway lines and motorways were digitised from OS maps. Numbers of deaths (and births) at successive radial distances from these hazards were counted and compared with expected numbers. The latter were based on a count of all PCs at similar distances. Relative case density ratios at successive distances from the hazards were obtained from observed and expected numbers, aggregated over similar sites. This was repeated for different hazard types and results were tested for evidence of systematic centrifugal case density gradients. PARTICIPANTS AND SETTING: All 22,458 children dying from leukaemia or cancer aged 0-15 years, in England, Wales, and Scotland, between 1953 and 1980. MAIN RESULTS: Relative excesses of leukaemias and of solid cancers were found near the following: (1) oil refineries, major oil storage installations, railside oil distribution terminals and factories making bitumen products; (2) motor car factories, coach builders, and car body repairers; (3) major users of petroleum products including manufacturers of solvents, paint sprayers, fibreglass fabricators, paint and varnish makers, plastics and detergent manufacturers, and galvanisers; (4) users of kilns and furnaces including steelworks, power stations, galvanisers, cement makers, brickworks, crematoria and aluminium, zinc, and iron/steel foundries; (5) airfields, railways, motorways and harbours. The findings for leukaemias and for solid cancers were indistinguishable. The hazard proximities of birth addresses were stronger than for death addresses. For children who had moved house between birth and death, the proximity effect was limited to the birth addresses. CONCLUSIONS: Childhood cancers are geographically associated with two main types of industrial atmospheric effluent namely: (1) petroleum derived volatiles and (2) kiln and furnace smoke and gases, and effluents from internal combustion engines.

Spatial clustering of childhood cancers in Great Britain.

STUDY OBJECTIVES: Firstly, to identify spatially close pairs and triplets of childhood leukaemias and cancers in Britain. Secondly, to compare pair frequencies with random expectations, identify excesses, and measure the diameters of any clusters. Thirdly, to infer possible causes. DESIGN AND SETTING: Stratified Poisson analyses of two comprehensive sets of childhood leukaemia and cancer data in Great Britain: seeking home address pairs within particular census enumeration districts (EDs) or postcodes (PCs). Numbers of pairs/triplets of leukaemia registrations sharing single or adjacent EDs were compared with Poisson, expectations in national ED strata with different numbers of households (HHs). Pairs/triplets of leukaemia/cancer deaths (and births) sharing a single PC were compared with Poisson expectations in national PC strata with different numbers of postal delivery points (DPs). Same and adjacent house pairs were identified individually among the same PC death pairs. Areal case densities were estimated around a sample of index cases, using their own PC grid coordinates, and those recorded in the central PC directory. PARTICIPANTS: These comprised, firstly, all cases of childhood leukaemia and non-Hodgkin lymphoma registered between 1966 and 1983 in England and Wales (ED analysis) and, secondly, all childhood leukaemia and cancer deaths between 1953 and 1980, in England, Wales, and Scotland (PC analyses at birth and at death). MAIN RESULTS: Short range spatial clustering was demonstrated (a) for leukaemia at place of registration, and (b) for leukaemia and cancer (separately and jointly) at both birth and death addresses. There was evidence of additional case pairing in adjacent PCs. Both data sets showed a relative local pair excess of about 1.5, within diameters of 300 metres. Secondary case densities, measured within 600 metres of a sample of unpaired index cases, were raised by the same ratio. The raised risk then tapered with increasing distance to about 3 km. Forty-four non-twin pairs had died at exactly the same address, far in excess of random expectation. This same house excess was due entirely to 31 sibling pairs. They also showed a relative excess of central nervous system and other solid tumours; but without the exact tumour type sibling concordances sometimes seen in MZ twins. The sibling pairs were only a small part of the overall excess of same PC pairs. CONCLUSIONS: Short range geographical clustering probably reflects two separate causes of childhood cancer, namely (a) an uncommon familial susceptibility to solid cancers, probably inherited, and (b) a group of long standing focal environmental hazards, most effective within a few hundred metres of the source, but detectable as far as 3 km.

Childhood cancers: space-time distribution in Britain.

STUDY OBJECTIVES: To examine a national data set of all childhood cancers for evidence of space-time interactions within three distinct sets of dates and places (at birth, at diagnosis, and at death), to show whether the patterns found for these events represent separate phenomena or statistically interdependent processes, and to see whether the childhood leukaemias and the childhood solid cancers have separate distinctive patterns in these respects. DESIGN: This was a space-time cluster analysis. The large number of cases enabled division of the data into two sets, one for hypothesis generation and the other for hypothesis testing. SETTING: England, Scotland, and Wales. SUBJECTS: A national collection of 22,360 children aged 0-15 years with fatal cancers and leukaemias in the period 1953 to 1980. MAIN RESULTS: There was significant clustering among the leukaemias and lymphomas on date and place of birth (particularly among cases born within 1 km and up to 5 months apart), and on date and place of diagnosis (particularly among cases diagnosed from 3 to 5 km apart and up to 9 months apart). There was no clustering among the solid cancers. These findings were confirmed in two separate analyses of two separate sets of data. CONCLUSIONS: The birth clustering was significant among pairs diagnosed at differing ages, and diagnosis clustering was significant among pairs born at different times, and it was concluded that the two types of clustering must be regarded as separate and statistically independent phenomena. Both the birth and the diagnosis clusters comprised many independent pairs of cases, with no large multiple case clusters. This suggests the involvement of multiple time-space localised exposures to hazards with short and constant latent intervals; probably an infectious agent or an environmental toxin. Given the separate nature of the two types of clustering, exposure to more than one hazard may be involved.

Leukaemia clusters in childhood: geographical analysis in Britain.

STUDY OBJECTIVE: To validate previously demonstrated spatial clustering of childhood leukaemias by showing relative proximities of selected map features to cluster locations, compared with control locations. If clusters are real, then they are likely to be close to a determining hazard. DESIGN: Cluster postcode loci and partially matched control postcodes were compared in terms of distances to railways, main roads, churches, surface water, woodland areas, and railside industrial installations. Further supporting comparisons between non-clustered cases and random postcode controls with those map features representable as single grid points were made. SETTING: England, Wales, and Scotland 1966-83. SUBJECTS: Grid referenced registrations of 9406 childhood leukaemias and non-Hodgkin's lymphomas, including 264 pairs (or more) separated by < 150 m, and grid references of random postcodes in equal numbers. MAIN RESULTS: The 264 clusters showed relative proximities (or the inverse) to several map features, of which the most powerful was an association with railways. The non-railway associations seemed to be statistically indirect. Some railside industrial installations, identified from a railway atlas, also showed relative proximities to leukaemia clusters, as well as to non-clustered cases, but did not "explain" the railway effect. These installations, with seemingly independent geographical associations, included oil refineries, petrochemical plants, oil storage and oil distribution depots, power stations, and steelworks. CONCLUSIONS: The previously shown childhood leukaemia clusters are confirmed to be non-random through their systematic associations with certain map features when compared with the control locations. The common patterns of close association of clustered and non-clustered cases imply a common aetiological component arising from a common environmental hazard--namely the use of fossil fuels, especially petroleum.

Comparison of long-term health problems following childbirth among Asian and Caucasian mothers.

While obstetric problems in Asian women have been documented, little is known about longer term health problems following childbirth. This study compares long-term postpartum morbidity in Asian and Caucasian women who had had an infant at a Birmingham maternity unit between 1978 and 1985. A total of 11,701 women returned the questionnaire asking about their experience of a list of 25 health problems. It was found that backache, frequent headaches, shoulderache and pains and weakness in the arms and legs all occurred more commonly among the 530 Asian women than in Caucasian women, even after standardizing for confounding factors. All these symptoms started within three months of the birth, lasted more than six weeks and had not previously been experienced. Most symptoms persisted for more than a year, and even after several years, many had not resolved. The possible role of vitamin D deficiency and the value of antenatal vitamin D supplements are discussed.

Accidental dural puncture in obstetric patients and long term symptoms.

OBJECTIVE: To examine the association between accidental dural puncture and long term headache and related symptoms. DESIGN: Postal questionnaire survey to elucidate new symptoms occurring after childbirth, and linking of these to data in obstetric and anaesthetic case notes. Women were surveyed between 13 months and nine years after delivery. SETTING: Birmingham Maternity Hospital. SUBJECTS: 4700 women who had delivered their most recent baby under epidural anaesthesia, 74 of whom had suffered an accidental dural puncture. MAIN OUTCOME MEASURES: Frequencies of new headache or migraine or neck ache starting within three months after childbirth and lasting over six weeks. RESULTS: Among the 74 women who had had an accidental dural puncture there were 17 (23%) who reported one or more of the above symptoms. By comparison, among those who had had an epidural anaesthetic but no recorded puncture, only 329 (7.1%) reported these symptoms. The duration of the headache or migraine or neck ache in the dural tap group ranged from nine weeks to over eight years. Ten of these women reported still unresolved symptoms. CONCLUSIONS: Conclusions on causality were tentative. Most women would remember a dural tap, and this might influence their reporting of subsequent symptoms attributable to the event. In addition, detailed characterisation of the symptoms was not available. Nevertheless, the findings provide a clear indication of the need for further study of the possible long term sequelae of accidental dural puncture.

Evaluation of obstetric analgesia and anaesthesia: long-term maternal recollections.

Opinions about pain relief were sought from a sample of 11,701 women 13 months to 9 years after giving birth. Their opinions related both to levels of satisfaction with the particular forms of pain relief used and to the presence of any feelings of deprivation of the birth process. Of all forms of pain relief examined epidural anaesthesia was associated with the highest levels of satisfaction. In vaginal deliveries, 69.4% of those who had an epidural were fully satisfied, compared with 29.5% for inhalation analgesia, 20.7% for pethidine and 29.4% for relaxation techniques. Women who had spontaneous deliveries and shorter labours were least satisfied with their epidurals, while the reverse was generally true for the other forms of pain relief. After an epidural for vaginal delivery 7.1% of women reported feelings of deprivation of the full pleasure of childbirth. This was higher than the 1.4% previously reported by women in the same maternity unit when questioned immediately after the delivery,(1) but still only represents a minority of women. After an emergency caesarean section administered under epidural feelings of deprivation were expressed by 5.1%, but by only 1.7% after an elective section under epidural. Among women using pethidine 3.5% felt that this had deprived them of the pleasure of giving birth.

Leukaemia clusters in Great Britain. 1. Space-time interactions.

STUDY OBJECTIVE: The aim was to test a large set of childhood leukaemia and lymphoma registrations for the presence of clusters in space and in time. DESIGN: The study was a space-time cluster analysis. SETTING: England, Wales and Scotland. PATIENTS: All registrations for leukaemia and lymphoma between 1966 and 1983 in children aged 0 to 14 years were examined. The records included date and age of registration, sex, diagnosis, and the map reference of the postcode of residence. Of the 9411 registrations, 8888 were suitable for inclusion. MAIN RESULTS: There was a statistically significant excess of case pairs occurring jointly within 0.5 km and 60 d of each other: 68 pairs compared with 50.0 expected. The excess was detectable in central England, in the north of England and Scotland, but not in the south west of England. It was concentrated within the age band 4 to 7 years and among the lymphatic leukaemias. Several potential artefacts were considered and excluded, but the possibility remained that clustered detections might be triggered by haematological examinations undertaken for some communicable disease. CONCLUSIONS: There was strong evidence of joint spatial-temporal clustering, with an excess of pairs separated by very short time and distance intervals. The causes are probably biological rather than artefactual, but further work will be necessary in order to exclude the latter.

Leukaemia clusters in Great Britain. 2. Geographical concentrations.

STUDY OBJECTIVE: The aim was to test a large set of childhood leukaemia and lymphoma registrations for the presence of short radius spacial clusters. DESIGN: The study was a geographical cluster analysis. SETTING: England, Wales and Scotland. PATIENTS: All registrations for leukaemia and lymphoma between 1966 and 1983 in children aged 0 to 14 years were examined. The records included date and age of registration, sex, diagnosis, and the map reference of the postcode of residence. Of the 9411 registrations, 8888 were suitable for inclusion. MAIN RESULTS: There was a significant excess of case pair addresses separated by < 0.5 km. There was also a significant excess of pairs sharing the same postcode. Both findings were based upon comparison with random pairs of postcodes drawn from the Central Postcode Directory. Examination for clustering at this very short range was based upon a clear prior hypothesis derived from the results of a study of space-time interaction, reported in a companion paper. CONCLUSIONS: It is postulated that the space-time interaction and the geographical concentrations shown here result from a common epidemic process. The epidemiology of this disease is characterised by short range geographical concentrations, with temporal non-homogeneity superimposed. The findings exclude certain artefacts which remained unresolved in the space-time interaction study. The distributions almost certainly reflect biological processes, and the most probable explanation is in terms of an infective process.

Investigation of long term problems after obstetric epidural anaesthesia.

OBJECTIVE: To examine the association between obstetric epidural anaesthesia and subsequent long term problems. DESIGN: Postal questionnaire on health problems after childbirth linked to maternity case note data. SETTING: Maternity hospital in Birmingham. SUBJECTS: 11701 women who delivered their most recent child during 1978-85 and who returned completed questionnaires. MAIN OUTCOME MEASURES: Frequencies of long term symptoms after childbirth. RESULTS: Compared with the 6935 women who did not have epidural anaesthesia the 4766 women who did more commonly experienced backache (903 (18.9%) with epidural v 731 (10.5%) without epidural), frequent headaches 220 (4.6%) v 199 (2.9%)), migraine (92 (1.9%) v 73 (1.1%)), neckache (116 (2.4%) v 112 (1.6%)), and tingling in hands or fingers (143 (3.0%) v 150 (2.2%)). The results could not be explained by correlated social or obstetric factors. The associations with head, neck, and hand symptoms were found only in women who reported backache. An excess of visual disturbances among women who had epidural anaesthesia (83 (1.7%) v 91 (1.3%)) was present only in association with migraine, but excess of dizziness or fainting (102 (2.1%) v 109 (1.6%)) was independent of other symptoms. 26 women had numbness or tingling in the lower back, buttocks, and leg, of whom 23 had had epidural anaesthesia. Of 34 women with spinal headache, nine (five after accidental dural puncture; four after spinal block) reported long term headaches. CONCLUSIONS: These associations may indicate a causal sequence, although this cannot be proved from this type of study. Randomised trials of epidural anaesthesia are required to determine whether causal relations exist.