抄録
Influences of birth seasons of babies and their mothers were investigated in perinatal phenomena of perinatal death, superficial malformations and low birth weight, in the deliveries during two periods in two maternity hospitals in Tokyo. Investigation wass made on 23, 947 deliveries in the 1930's and 6, 983 deliveries in and after 1966.
In the 1930's, when birth seasonality was most remarkable, all three phenomena showed variation by birth season of babies, especially when they were born from the mothers born in the winter months (Nov-Apr) . Seasonal variations and mean values of abnormality rates were less in the deliveries from mothers born in the summer months (May-Oct), especially in perinatal death rate. In and after 1966, when birth seasonality was almost lost, every difference by birth season of babies or mothers was also insignificant.
Mothers born in the summer season of less frequent births showed less risk to the seasonal occurrence of perinatal death.
