Maier W
Geburtshilfe Frauenheilkd. 1978 Apr;38(4):281-4.
The statistics on twin deliveries for Bavaria from 1920-1925 were compared to those for 1972-1976. The number of twin deliveries showed a reduction from 15 per thousand in 1920-1925 to 9 per thousand in 1972-1976. The largest number of twin mothers were young primigravidas or older multi-gravidas. The percentage of twins of the same sex increased by 4.7% for boys and 5.7% for girls. The percentage of twin deliveries of different sex decreased by about 7%. Of all twin deliveries in Bavaria from 1920-1976 66% were of the same sex and 34% had different sex.
将巴伐利亚州1920 - 1925年的双胎分娩统计数据与1972 - 1976年的进行了比较。双胎分娩数量从1920 - 1925年的每千人15例降至1972 - 1976年的每千人9例。双胎母亲中最多的是年轻初产妇或年长经产妇。同性双胞胎的比例男孩增加了4.7%，女孩增加了5.7%。异性双胎分娩的比例下降了约7%。在1920 - 1976年巴伐利亚州所有的双胎分娩中，66%是同性的，34%是异性的。
