Excess Of Winter Births Research Articles

Season of Birth in Schizophrenia

Although it is well recognised that schizophrenic patients are more often born in winter, the significance of this finding remains obscure. Data relating to season of birth and family history were analysed for 561 patients with an ICD-9 diagnosis of schizophrenia. Patients with no family history of any psychiatric disorder group were significantly more likely to be born in winter than patients with a first-degree relative affected by schizophrenia. In comparison with normal population controls, only those without a family history exhibited a significant excess of winter births, suggesting an environmental factor of greater aetiological significance in these patients.

Season-of-birth and acute leukemia of infancy.

Because of its short and clearly delineated latency period, acute leukemia of infancy is particularly suited to etiologic analysis. From 1950 to mid-1985, 31 infants with acute leukemia (less than 1 year of age) were registered at the University of Texas, M.D. Anderson Cancer Center at Houston. The medical records of these infants were reviewed for demographic and birth information. Of the 31 infants, 14 (45%) were Hispanic. The sex ratio was 3:1 male/female) for white infants and 5:9 for Hispanic infants. Of the white infants, half had acute lymphocytic leukemia, compared with all but one of the Hispanic infants. There was a significant excess of winter births among the infants diagnosed with acute leukemia (P less than 0.05). The significant association between season-of-birth and the occurrence of leukemia cases is suggestive of periodicity of an environmental etiologic agent, perhaps acting in concert with endogenous rhythmicities in susceptibility to that agent. This finding is deserving of further study.

Seasons of birth and subtypes of schizophrenia.

Many studies show a higher rate of birth of schizophrenic patients during the winter and early spring months. This is particularly prominent in studies involving northern European countries and the northern part of the United States. The interpretations for this apparent seasonality remain highly speculative. We examined the seasons of birth of 472 patients carrying the diagnosis of schizophrenia. We also studied the gender and paranoid vs nonparanoid subtypes of this subject group. The total group does not show an excess of winter births. The same is true for total male (n = 193) and total female (n = 279) schizophrenic patients. The different subtypes of female patients show a homogenous distribution by seasons of birth; but the male paranoid schizophrenia group (n = 102) shows a significant increase of births during the first quarter of the year. The findings are interpreted according to the prevailing hypotheses of schizophrenia. The implications of these findings are discussed.

Season of birth in infantile autism.

Existing evidence suggests an excess of winter births in schizophrenia and inconsistent results for other psychiatric conditions. The present study examined seasonal effects of birth among autistic individuals. Results revealed an excess of spring and carly summer births and an underrepresentation of winter and fall births. However, this pattern was obtained only for the male, nonverbal, and lower-functioning autistic subgroup.

Season of birth among the sibs of schizophrenics.

The season of birth distribution of 1,039 sibs of Canadian schizophrenic patients was compared with that of births in the Canadian general population over the same time period. The excess of winter births observed among the schizophrenics was not found among their sibs.

Mental disorder and season of birth--a southern hemisphere study.

Studies on the relationship between season of birth and mental disorder have been substantially confined to northern hemisphere regions. Such studies have generally found an excess of winter births of schizophrenics, and variably an excess of winter births of manic-depressive and mentally retarded patients. In the present study information on sex, diagnosis and date of birth was obtained on all 20,358 patients first admitted to psychiatric facilities in New South Wales between July 1970 and June 1974 and born in New South Wales. The collective 1962-71 monthly live-births for New South Wales were used as a control. A significant winter excess was found for the female schizophrenic group, while a significant spring excess was found for neurotic patients, most marked in those with anxiety neurosis. It is hypothesized that the relationship between schizophrenia and winter birth is consequent upon a greater sensitivity of schizophrenics to those physiological factors which determine conception in the general population.

Spina Bifida and Anencephalus in Greater London

In order to make comparisons with the findings in a high frequency area, South Wales, with those in a low frequency area, south-east England, a birth frequency and family study was made of all births with neural tube malformations (spina bifida cystica, encephalocele, anencephaly, and iniencephaly) in 32 of the 33 London Boroughs over a 3-year period from 1 April 1965 to 31 March 1968. The births were ascertained through local authority registers, stillbirth and infant death certificates, and hospital records. The frequencies found were 1·54 for spina bifida (including encephalocele) and 1·41 for anencephaly (including iniencephaly). This was less than four tenths of the South Wales frequency. Evidence of an excess of winter births was found for both types of malformation, with a peak for conceptions in February, March, and April. The parents of 870 of the original 1209 index patients were traced and visited for the family survey. The usual social class effect was seen, a deficit of fathers in social class I and II. The birth order distribution of legitimately born patients standardized for maternal age showed only a small excess of firstborn and a deficit rather than an excess of lateborn. For maternal age, however, standardized for birth order, there was an excess of patients born to mothers under 20 and over 35 years of age. The whole family study sample showed a striking excess of patients born to parents from India and Pakistan compared to parents born in the West Indies in relation to households of immigrant parents in the 1966 sample Census. A small sample of 164 patients with matched controls had more parents born in Ireland and India and Pakistan and fewer born in south-east England and the West Indies than the controls. The proportions of sibs affected with spina bifida and anencephaly were 3·42% for spina bifida index patients and 5·44% for anencephaly. For patients born after the index patient the proportions were 5·17 and 4·17%, respectively. The overall risk to sibs was lower than that shown in the South Wales survey, but substantially higher relative to the population birth frequency. The risk to sibs was not apparently influenced by father9s social class but there was an indication of an effect of mother9s father9s social class, with a lower risk where mother had grown up in a class I, II, or IIIa home. There was no apparent influence of grandparental birth place. There was no apparent effect of a relative affected other than a sib. Among cousins a significant increase over the population birth frequency was seen only in mother9s sisters9 children. The findings, like those of earlier surveys, suggest a multifactorial aetiology of the neural tube malformations, depending both on genetic predisposition and environmental triggers.