Course of pregnancy, family history and genetics in children with spina bifida.

Course of pregnancy, family history and genetics were evaluated in 257 children with spina bifida and compared with 537 non-malformed controls investigated under the same criteria. Birth data exhibited a significant seasonality with a maximum in January and a minimum in July which differed from the average distribution of birth data in Bavaria (maximum April, minimum October). The total number of pregnancy disturbances was 60.6% in mothers of spina bifida children, whereas this figure amounted to 30.1% in mothers of the control group. This high incidence of pregnancy disturbances in spina bifida was due to a high rate of diseases (6 times above controls) and drugs (6 times above controls) during early pregnancy. In 22.9% of children with spina bifida malformed relatives were found, whereas this was the case in only 6.4% of the children of the non-malformed control group. Not only malformations of the central nervous system but also malformations of other organ systems were found to be increased in relatives. This is a pointer not only to genetic influences as well-known aetiological factor, but also towards a generally higher susceptibility to malformation genesis in a relatively small group of persons. Risk of recurrence was 0.5% if one parent was affected and 4% if a sibling was affected.