目的　探讨足月小样儿早发型血小板减少症（EOT）发病的围生期危险因素。方法　选取2008年4月至2014 年7月收治的93例EOT足月小样儿为病例组，另选同期住院出生体质量相差<250 g、胎龄相差<3天的非EOT足月小样 儿为对照组，采用1:1或1:2配对病例对照研究，回顾性收集两组患儿的围生期资料、入院后实验室检查结果等，比较两 组患儿的差异。结果　病例组的宫内窘迫（41.9%对25.8%, χ2=7.35， P=0.007）、羊水污染（39.8%对27%， χ2=4.66， P=0.031）、早发型败血症（7.5%对1.7%， χ2=4.34， P=0.037）的发生率均高于对照组，差异有统计学意义。条件logistics 回归分析发现，宫内窘迫（β=0.60，OR=1.82，95%CI=1.04~3.17， P=0.035）、早发型败血症（β=1.69，OR=5.44， 95%CI=1.11~26.76， P=0.037）与EOT有关。结论　宫内窘迫、早发型败血症为足月小样儿EOT发病的危险因素。

Objective　To explore the perinatal risk factors of early onset thrombocytopenia (EOT) in full-term small for gestational age infants. Methods　A 1:1 or 1:2 matched case control study was carried out. A total of 93 full-term small for gestational age infants with EOT were selected from April 2008 to July 2014 as the case group, and the non EOT full-term small for gestational age infants with the birth weight difference <250 g and the gestational age difference <3 days were selected as the control group. The clinical data during perinatal period and laboratory examination results after admission were collected retrospectively. And the differences between the two groups were compared. Results　The incidence of intrauterine distress (41.9% vs. 25.8%, χ2=7.35, P=0.007), amniotic fluid contamination (39.8% vs. 27%, χ2=4.66, P=0.031), and early-onset sepsis (39.8% vs. 27%, χ2=4.66, P=0.031) were significantly higher in the case group than those in the control group. Conditional logistics regression analysis showed that intrauterine distress (β=0.60, OR=1.82, 95%CI=1.04~3.17, P=0.035) and early-onset sepsis (β=1.69, OR=5.44, 95%CI=1.11~26.76, P=0.037) were related to EOT. Conclusions　Intrauterine distress and early-onset sepsis are risk factors for the onset of EOT in full-term small for gestational age infants.