目的 探讨晚期早产儿中小于胎龄儿（SGA）发生的危险因素。方法 回顾性分析2019年1月至2021年12月在医院出生并收入新生儿重症监护室，胎龄34~36⁺⁶周的晚期早产儿的临床资料，根据胎龄和出生体质量将研究对象分为SGA组和适于胎龄儿（AGA）组。使用倾向性评分匹配对两组采用1:1最邻近匹配法，得到组间协变量均衡的样本，比较两组间临床特征。采用多因素条件logistic回归分析晚期早产儿中SGA发生的影响因素。结果 SGA组纳入239例，AGA组纳入239例，两组性别、出生胎龄比较差异均无统计学意义（P>0.05）。SGA组的产前糖皮质激素治疗比例，妊娠期高血压疾病、双胎妊娠发生率高于AGA组，胎膜早破（≥18 h）发生率低于AGA组，差异有统计学意义（P<0.05）。多因素条件logistic回归分析结果显示，产前糖皮质激素治疗、妊娠期高血压疾病、双胎妊娠是晚期早产儿SGA发生的独立危险因素（P<0.05）。结论 减少产前糖皮质激素治疗，预防妊娠期高血压疾病，避免双胎妊娠是减少晚期早产儿SGA的主要措施。

Objective To investigate the risk factors of the occurrence of small for gestational age (SGA) in late preterm infants. Methods The clinical data of late preterm infants with gestational age of 34~36⁺⁶ weeks born in Xiamen Maternal and Child Health Hospital and admitted to the neonatal intensive care unit from January 2019 to December 2021 were retrospectively analyzed. According to the gestational age and birth weight, the subjects were divided into SGA group and appropriate gestational age (AGA) group. The propensity score matching function of SPSS software was used to match the two groups with the 1:1 nearest neighbor matching method to obtain the between-group correlation. The clinical features between the two groups were compared. The influencing factors of SGA occurrence in late preterm infants were analyzed by multivariate conditional logistics regression. Results There were 239 patients in SGA group and 239 patients in AGA group, and there were no significant differences in gender and gestational age between the two groups (P>0.05). The proportion of prenatal glucocorticoid therapy, the incidence of gestational hypertension and twin pregnancy in SGA group was higher than that in AGA group, and the incidence of premature rupture of membranes (≥18h) in SGA group was lower than that in AGA group, and the differences were statistically significant (P<0.05). The results of multivariate conditional logistics regression analysis showed that prenatal glucocorticoid therapy, gestational hypertension and twin pregnancy were independent risk factors for SGA occurrence in late preterm infants (P<0.05). Conclusions Reduction of prenatal glucocorticoid treatment, prevention of hypertension during pregnancy, and avoidance of twin pregnancy are the main measures to reduce SGA in late prematureinfants.