Farhud D D, Kamali M S, Marzban M
Anthropol Anz. 1986 Mar;44(1):61-6.
234 218 births (1975-1983) from a hospital in Tehran have been analysed for seasonality of birth and sex ratio. The results show more births in winter and less births in fall. The sex ratio is higher in summer and lower in fall. The occurrence of multibirths shows higher twinning and triplet rates in spring and fall, respectively, whereas lower twinning and triplet rates occur in winter and summer, respectively. It could be demonstrated that geographical factors influence the rates of births and multibirths as well as the sex ratio.
对德黑兰一家医院1975年至1983年期间的234218例出生情况进行了季节性和性别比分析。结果显示，冬季出生人数较多，秋季出生人数较少。夏季的性别比更高，秋季更低。多胞胎的发生率显示，春季和秋季的双胞胎和三胞胎率分别更高，而冬季和夏季的双胞胎和三胞胎率分别更低。可以证明，地理因素会影响出生和多胞胎率以及性别比。
