Background: Environmental physical activity is known to be associated with many factors of human homeostasis, such as fetal development, birth number, and some genetic abnormalities. This study sought to investigate possible temporal links between the occurrence of congenital heart disease and solar, geomagnetic, and cosmic ray activities.
Patients and methods: The study sample include 79,085 infants born live at a tertiary medical center in central Israel from 1995 to 2005, of whom 1739 were diagnosed with congenital heart disease, including 309 with patent ductus arteriosus (PDA). The number of infants with congenital heart disease (total and excluding PDA) was analyzed against the values of the physical parameters, as derived from international indices, by year of birth and 1 year before and by month of birth and 9 months before. Pearson correlation coefficients and their probabilities were calculated.
Results: The number of cases of infantile congenital heart disease over the 132-month study period significantly correlated with solar activity (r=0.5, p<0.0001) and with cosmic ray activity (r=-0.45, p<0.0001). On analysis by year, correlations were as follows: with solar activity 1 year before delivery, r=0.71, p=0.014, n=11, and at time of delivery, r=0.66, p=0.026; with cosmic ray activity, 1 year before delivery, r=-0.66, p=0.03, and at time of delivery, r=-0.61, p=0.047, n=11. The levels of correlation and probability were higher for solar activity indices at conception (9 months or 1 year before delivery) than at birth. Significance was maintained when cases of PDA were excluded.
Conclusion: The monthly number of infants born with congenital heart disease is directly correlated with the level of solar activity and inversely correlated with the level of cosmic ray activity during pregnancy, predominantly in the month of conception. The mechanism underlying the possible effect of solar activity on the occurrence of congenital heart disease warrants additional studies.