Williams R L, Chen P M
N Engl J Med. 1982 Jan 28;306(4):207-14. doi: 10.1056/NEJM198201283060404.
The perinatal mortality rate in California decreased rapidly in the 1970s; neonatal mortality fell about twice as fast as fetal mortality. Decreases in birth-weight-specific mortality accounted for 81 per cent of the decline in the perinatal rate, with only 19 per cent due to improvements in birth weight. No improvement was observed in the birth-weight distribution for blacks. The decrease in mortality rates was significantly faster for cesarean deliveries than for vaginal births. By 1977, all birth-weight-specific fetal mortality rates for cesarean sections were equal to those for vaginal deliveries or lower. For infants weighing less than 2000 g, perinatal mortality rates were also significantly lower for infants born by cesarean section than for infants delivered vaginally. These results suggest that much of the recent decrease in perinatal mortality rates can be attributed to the advent of neonatal intensive care and the increased rate of cesarean section.
20世纪70年代，加利福尼亚州的围产期死亡率迅速下降；新生儿死亡率下降速度约为胎儿死亡率的两倍。特定出生体重死亡率的下降占围产期死亡率下降的81%，仅有19%归因于出生体重的改善。黑人的出生体重分布没有改善。剖宫产的死亡率下降速度明显快于阴道分娩。到1977年，所有剖宫产的特定出生体重胎儿死亡率均等于或低于阴道分娩。对于体重不足2000克的婴儿，剖宫产出生的婴儿围产期死亡率也显著低于阴道分娩的婴儿。这些结果表明，近期围产期死亡率的下降很大程度上可归因于新生儿重症监护的出现和剖宫产率的提高。
