Monthly number of preterm births and environmental physical activity.
Recent studies have reported links between external physical factors and human homeostasis.


OBJECTIVE
to determine whether the monthly values of specific physical environmental factors are associated with the monthly number of preterm births in a major medical center in Israel.


METHODS
The sample included 1006 infants weighing less than 1500g born live to 774 mothers during 96 consecutive months (1995-2002) at a tertiary medical center in Israel. Monthly values of indices of solar, cosmic ray, and geomagnetic activity for the same period were obtained from national data monitoring facilities in the United States of America, Russia, and Finland. The findings were statistically correlated with the monthly number of preterm births.


RESULTS
The number of preterm births correlated with the month of the year (1-12), with a progressive rise in the number of infants born as the year progressed (p = .02). The monthly number of preterm births showed a significant and direct correlation with solar activity indices (r = .32, p = .0016), and a significant and inverse correlation with cosmic ray activity indices (r = -0.3, p = .008). The relation was significant only for singelton births and for the whole group of preterm newborns, but not for multiple pregnancies.


CONCLUSIONS
Our findings suggest that solar and cosmic ray activity may play a role in the timing of premature labor, however in multiple pregnancies additional factors are dominant.
Stoupel
Elyiahu
E
Departments of Neonatology Schneider Children's Medical Center of Israel, Petah Tiqwa. stoupel@inter.net.il
Sirota
Lea
L
Osovsky
Micki
M
Klinger
Gil
G
Abramson
Evgeny
E
Israelevich
Peter
P
Sulkes
Jaqueline
J
Linder
Nechama
N
D003359:Cosmic Radiation; D003627:Data Interpretation, Statistical; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007557:Israel; D008280:Magnetics; D008297:Male; D011247:Pregnancy; D011272:Pregnancy, Multiple; D047928:Premature Birth / Q000453:epidemiology*; D011336:Probability; D019445:Solar Activity; D013997:Time Factors