The connection between month of birth and gametopathy. An investigation of patients with Down's, Klinefelter's and Turner's syndrome.
Fluctuations in the distribution of births throughout the year in the Netherlands were studied. This curve could not be distinguished from that of other northwest European countries except for small variations. Two maxima and two minima are appearing to be linked to specific seasons. The maxima arise in winter and summer, being equivalent to spring and autumn conceptions. HUNTINGTON called this phenomenon the 'basic animal rhythm'. An explanation for this phenomenon was given, using two heuristic hypotheses:
1— Seasonal fluctuations in the 'norinal' conception curve are caused by two basic oestric patterns, of which the phylogenetic younger (polyoestrus) is superimposed on the phylogenetic older (mono- or dioestrus).
2 — The biological background of these seasonal fluctuations in the 'normai' conception curve can be explained by alternating periodes of ovulatory and anovulatory cycles.
Literature studies concerning the connection between month of birth of patients with congenital as well as many psychopathological aberrations convinced us that here too rhythmic fluctuations are quite apparent. These fluctuations are synchronous with the 'normal' rise and fall, and thus linked to the same season, though with a greater amplitude.
In the discussion concerning the cause of this phenomenon, chromosomal aberrations have a special place since nondisjunction can only occur before or around the time of fertilization and not later during pregnancy. The birth curves of 441 patients with Down's syndrome, 317 patients with Klinefelter's syndrome and 126 patients with Turner's syndrome were studied. These chromosomal aberrations gave almost analogous birth curves, which moreover were simden- to those found in the case of congenital anomalies without chromosomal aberrations. Here too the maxima and minima are synchronous with that of the 'normai' birth curve, though with a greater amplitude, a phenomenon which we have called 'deviant birth curve'. Because of the universality of such a 'deviant birth curve' we feel that we may conclude that this is due to a biological rule.
These findings support the opinion that the factors responsible for pathological progeny, including those without chromosomal aberrations, exert their influence not during the pregnancy but around the time of fertilization (or even before). This could be a justification for the term 'pathological conceptions'.
A third heuristic hypothesis was formulated to explain this biological rule.
3 —The disproportionate increase of 'pathological conceptions' during spring and autumn, and the disproportionate decrease during winter and summer are caused by the interference of the two basic oestric patterns.
Such an interference could slow down the preovulatory ripening of the egg-cell resulting in overripeness-ovopathy. In addition it is pointed out that spermatopathy too could occur zinder the influence of climatological factors. The investigation of birth curves of mothers and fathers of patients with Down's syndrome suggested a constitutional factor predisposing to the conception of a child with this syndrome. It is argued that this predisposing factor could likewise be due to overripeness-ovopathy.
Finally the usefulness of studying the month of birth of various aberrations is emphasized. Through this we could 1°. distinguish genocopies from phenocopies, 2°. provide a better outline of the consequences of overripeness of the egg (and sperm) and 3°. obtain a better insight into combinations of symptoms in human pathology, which have been, up till now, not understood. Through this our insight info the human phenomenology could be widened.