Nonaka K, Miura T
Department of Hygiene, Teikyo University School of Medicine, Tokyo, Japan.
Acta Genet Med Gemellol (Roma). 1987;36(3):365-72. doi: 10.1017/s0001566000006127.
Baptism records of parishes in London and its vicinities from 1581 to 1760 (168,238 maternities) were investigated to estimate the twinning rate and its secular and seasonal variations. Total, estimated dizygotic (DZ), and estimated monozygotic (MZ) twinning rates were 1.1%, 0.8% and 0.3%, respectively. MZ twinning rate varied during the 18 decades, with a significantly low rate (0.11%) in the early 17th century (1621-1640). Significant seasonal variations of the twinning rate according to the month of baptism was observed in both DZ and MZ twins. DZ twins were born more frequently in spring and fall in general. Parish records obtained from four parishes near Manchester in England showed an inversed seasonal variation with peaks in winter and summer. An interpretation of this difference was discussed in a context of environmental factors. In the low MZ period, 1621-1640, MZ or like-sexed twins were apparently less frequent in summer (April to October). This result could be explained by a decrease of MZ twins and/or a greater loss of like-sexed DZ twins.
对伦敦及其周边教区1581年至1760年的洗礼记录（168,238例产妇）进行了调查，以估计双胎率及其长期和季节性变化。总双胎率、估计的异卵（DZ）双胎率和估计的同卵（MZ）双胎率分别为1.1%、0.8%和0.3%。MZ双胎率在这18个十年间有所变化，在17世纪早期（1621 - 1640年）显著较低（0.11%）。在DZ和MZ双胎中均观察到根据洗礼月份的双胎率有显著的季节性变化。一般来说，DZ双胎在春季和秋季出生更为频繁。从英国曼彻斯特附近四个教区获得的教区记录显示出相反的季节性变化，在冬季和夏季出现峰值。在环境因素的背景下讨论了这种差异的一种解释。在MZ双胎率较低的时期，即1621 - 1640年，MZ或同性双胎在夏季（4月至10月）明显较少。这一结果可以通过MZ双胎数量的减少和/或同性DZ双胎更大的损失来解释。
