目的 探讨单胎小体型脆弱新生儿（SVN）的发病率变化趋势及其影响因素，分析父母因素与SVN的关联。方法 采用回顾性队列研究，选取2019年1月至2023年12月早孕期（孕14周前）在产科建档并定期产检至分娩的13 020名孕妇作为研究对象。根据新生儿状况，符合SVN定义的纳入SVN组，其余纳入对照组。SVN包括早产（PT）、小于胎龄儿（SGA）和低出生体重儿（LBW）3种表型。比较两组孕妇基线资料、孕期并发症、父亲年龄和体质指数（BMI），以及妊娠结局，并采用logistic回归分析SVN的父母影响因素。结果 研究期间单胎分娩新生儿13 020名，其中SVN 1 658例，发病率为12.73%；SVN的3种表型PT、LBW和SGA分别为412、329、1 246例，发病率为3.16%、2.53%和9.57%。PT和LBW的发病率，2023年较2019年分别下降了49.12%和29.73%，但SGA发病率2023年较2019年升高了37.04%。所有孕妇中，壮族占所有种族37.55%，本科及以上学历占82.33%，经产妇48.21%。孕前有疾病史的累计719例（5.52%），甲状腺功能异常最多（4.21%，548/13020）。3 582名孕妇在孕前行地中海贫血（简称“地贫”）相关基因检测，1 864例检出阳性（检出率52.04%），其中轻型α地贫检出率最高（674例，18.82%）。父亲≥35岁者占比37.08%，超重及肥胖（BMI≥24 kg/m²）占比50.53%，消瘦仅占2.73%。多因素logistic回归分析显示，母亲孕前超重、经产妇、AB血型为SVN的保护性因素（P<0.05）；母亲孕前消瘦，妊娠合并多囊卵巢综合征（PCOS），妊娠期高血压疾病（HDP）为SVN的危险因素（P<0.05）。SVN组新生儿胎龄较小、身长较短、体重较轻，新生儿窒息及死亡率较高，与对照组的差异有统计学意义（P<0.05）。结论 SVN的3种表型在5年间的发病率变化趋势不同，SGA的发病率有升高趋势，应重点关注。SVN发生与母亲孕前营养状态、合并PCOS，孕期HDP密切相关，故应加强围产期保健、预防孕期HDP。本研究并未发现父亲年龄及BMI对SVN产生具体影响。

Objective To explore the changing trend of the incidence of singleton small vulnerable neonates (SVN) and its influencing factors, and to analyze the association between parental factors and SVN. Methods A retrospective cohort study was conducted, recruiting 13,020 pregnant women who established prenatal records before 14 weeks of gestation between January 2019 and December 2023 and received standardized antenatal care until delivery. Based on neonatal outcomes, those meeting the SVN criteria were assigned to the SVN group, with the remaining assigned to the control group. SVN encompassed three phenotypes: preterm birth (PT), small for gestational age (SGA), and low birth weight (LBW). Baseline maternal characteristics, pregnancy complications, paternal anthropometric parameters, and pregnancy outcomes were compared between the two groups. Logistic regression analysis was employed to identify parental influencing factors for SVN. Results During the study period, the overall SVN incidence was 12.73% (1658/13020), comprising PT (3.16%, 412/13020), LBW (2.53%, 329/13020), and SGA (9.57%, 1246/13020). The incidence rates of PT and LBW decreased by 49.12% and 29.73% respectively in 2023 compared with 2019, but the incidence rate of SGA increased by 37.04% in 2023 compared with 2019. Among all pregnant women, the Zhuang ethnic group accounted for 37.55% of all ethnic groups, those with a bachelor's degree or above accounted for 82.33%, and multiparous women accounted for 48.21%. A total of 719 pregnant women (5.52%) had a history of diseases before pregnancy, and abnormal thyroid function was the most common (4.21%, 548/13020). A total of 3,582 pregnant women underwent pre-pregnancy genetic testing related to thalassemia, and 1,864 cases were detected positive (detection rate 52.04%), among which the detection rate of alpha thalassemia minor was the highest (674 cases, 18.82%). The proportion of fathers aged 35 or above was 37.08%, while the proportion of those who were overweight or obese (BMI ≥ 24 kg/m²) was 50.53%, and the proportion of those who were underweight was only 2.73%. Multivariate logistic regression analysis revealed that maternal pre-pregnancy overweight, multiparity, and AB blood type were protective factors for SVN (P<0.05); whereas maternal pre-pregnancy underweight, pregnancy complicated by polycystic ovarian syndrome (PCOS), and gestational hypertensive disorders (HDP) were identified as risk factors for SVN (P<0.05). Neonates in the SVN group exhibited significantly smaller gestational age, shorter body length, lower birth weight, and higher rates of neonatal asphyxia and mortality, with statistically significant differences (P<0.05). Conclusions The three phenotypic subtypes of SVN exhibited divergent incidence trends over the five-year period, with the incidence of SGA demonstrating an upward trajectory warranting focused attention. The occurrence of SVN showed strong associations with maternal pre-pregnancy nutritional status, comorbid PCOS, and HDP, highlighting the necessity for enhancing antenatal care and preventing HDP during pregnancy. This study did not identify significant impacts of paternal age or BMI on SVN.