Reduced Solar Activity Favors Twin Maternities

Abstract

Mechanisms underlying effects of physical factors on twin births are unclear. The present work studied an association between monthly and yearly multiple birth rates (MBRs) in the Novosibirsk region, south-west Siberia, in relation to solar activity (sunspot numbers) and geomagnetic activity (Ap index) from 1957 to 2008. The difference was verified by comparing the yearly MBR observed in 3-year peaks (M = 7.36, SD = 0.33 per 1,000 births) and 3-year troughs (M = 8.10, SD = 0.31 per 1,000 births, p < .001) of an 11-year solar cycle. An inverse correlation (r = –.60, p < .001) was found between sunspot numbers and MBR for a lag of 1 year. Cross-spectral analysis of a 52-year time series established a common signal with the period of 10.5 years, as well as high coherence (K(2) = 0.87). The multiple regression analysis revealed a significant interaction of solar and geomagnetic effects upon the frequency of twin maternities. The results show that elevated solar activity within the 11-year cycle coinciding with the time of conception inhibits multiple births in a manner depending on geomagnetic activity. It is hypothesized that the likely mechanism underlying the association is early fetal loss induced by solar radiation/flux and its terrestrial mediators.

Solar activity at birth predicted infant survival and women's fertility in historical Norway

“…Folate is needed for DNA synthesis and for the maintenance of the epigenome [39] and is thus essential for the development of healthy and fecund individuals during gestation [13]. Folate deficiency during pregnancy is associated with higher morbidity and mortality (reviewed in [40]), and hence, increased folate degradation in solar maximum periods could result in folate deficiency in pregnant women and, consequently, fetal loss [19,20] as well as reduced subsequent survival of children [13]. Another candidate explanation may be the selection for specific genotypes associated with folate loss and vitamin D biosynthesis at the time of conception or early pregnancy in relation to solar activity.…”

“…However, to our knowledge, such research with respect to terrestrial vertebrates is lacking (but see [18]). A few studies have focused on how periods of high solar activity (as a proxy for UVR) during gestation may adversely affect humans through fetal loss [19,20] and through the onset of diseases in adult life [21][22][23]. Furthermore, some studies have investigated how solar activity during embryonic development predicts lifespan.…”

“…high solar activity (as a proxy for UVR) during gestation may adversely affect humans through fetal loss [19,20] and through the onset of diseases in adult life [21][22][23]. Furthermore, some studies have investigated how solar activity during embryonic development predicts lifespan.…”