有或没有对后出头使用产钳的臀位分娩的新生儿死亡率。

Br J Obstet Gynaecol. 1975 Oct;82(10):783-5. doi: 10.1111/j.1471-0528.1975.tb00573.x.

A retrospective study of 1423 liveborn breech deliveries occurring in one hospital from 1964 to 1973 inclusive showed that application of forceps to the aftercoming head of infants between 1 and 3 kg birth weight was associated with a significant reduction in neonatal mortality.

一项对1964年至1973年（含）在一家医院发生的1423例活产臀位分娩的回顾性研究表明，对出生体重在1至3千克之间的婴儿后出头使用产钳，可显著降低新生儿死亡率。