Search

Copyright of Polish Journal of Allergology / Alergologia Polska is the property of Termedia Publishing House and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The epidemiology of multiple pregnancy is complex and depends on various factors including age, race, genetic and environmental factors, season of conception and, more recently, iatrogenic factors. In recent years, twinning rate increased dramatically especially in countries where ovulation induction and assisted reproductive technologies are widely used. Multiple pregnancies are most frequent in Nigeria where majority of them are dizygotic. The lowest frequency of twinning is observed in Japan where almost 70% of multiples are monozygotic. This paper discusses genetic, environmental and sociocultural factors which are related to the "epidemic" of multiples.