Defects of the central nervous system in Finland. II. Birth order, outcome of previous pregnancies and family history

Abstract

Seven hundred and ten cases with defects of the central nervous system (CNS) reported to the Finnish Register of Congenital Malformations in 1965-73 were analysed with regard to possible etiological factors. A time-area matched birth for every case, 259 cases of polydactyly, and official statistics for the entire country were used as controls. High birth order turned out to be a risk factor especially for the group of hydrocephaly, maternal age not taken into account. When this confounding factor had been ruled out, it was found that high birth order was associated with anencephaly and high maternal age with hydrocephaly. However, a combination of both these factors gave the most striking association in both groups of defects. Higher rates of abortions and stillbirths in previous pregnancies, previous live births with CNS defects or any kind of defects were significantly associated with the birth of children with CNS defects. The rate of twinning was found to be higher in the study group than in the general population, and in the great majority of twin births the CNS defective child was the later born partner. Parental profession did not seem to be associated with the outcome of pregnancy. The significance of the socio-economic status and other confounding factors are discussed in connection with the concept of the marital status of mothers.

Neural tube defects in Victoria, Australia: potential contributing factors and public health implications

“…Similar effects have previously been reported in France, 25 England 26 and Wales, 27 however a number of other studies have reported no effect of age after adjusting for parity. [28][29][30][31] As information on the maternal characteristics of cases terminated was not available for the multivariate analyses, and as there was a higher proportion terminated among older mothers, it is possible that the increased risk found in younger mothers may be a result of these patterns of reporting described. However, the univariate analyses, which include at least some data on maternal age for cases terminated, also showed a distinct linear trend of increasing risk with increasing maternal age.…”

Incidence of neural tube defects in Afyonkarahisar, Western Turkey

“…Several studies have reported an independent effect of maternal age and birth order on NTDs (Fedrick, 1970;Naggan, 1971;Hay and Barbano, 1972;Granroth et al, 1978;İmaizumi, 1979;Feldman et al, 1982). Older mothers are known to be at a higher risk for trisomy 13, 18 and 21.…”

Congenital defects and occupational factors. A comparison of different methodological approaches.

“…Some of them, e.g., parental age and maternal medication and infections during pregnancy have been extensively studied, and there are indirect indications that parents' occupations may influence the outcome, Reprint requests to: Dr. Peter C. Holmberg, Institute of Occupational Health, Haartmaninkatu 1, SF-00290 Helsinki 29, Finland. 0355-3140/79/040328-5 since a higher incidence of central nervous system (CNS) anomalities has been found to occur in the lower social classes (1,3,4).…”