Objective Studies have suggested an association between prenatal care (PNC) and preterm birth (PTB). We evaluated trends in PTB and association of PNC and PTB.

Study Design This was a retrospective cohort study of singleton, viable nonanomalous deliveries from 1991 to 2018. PNC utilization was defined by World Health Organization using number of visits: adequate (≥8), suboptimal (5–7), and inadequate (<5). Primary outcome was PTB. Tests of trend were used to assess changes in PTB over time. Baseline characteristics and outcomes were compared. Logistic regression estimated the association of PNC and PTB. We evaluated for effect modification by year of birth.

Results Of 92,294 patients, 14,057 (15%) had PTB. Inadequate and suboptimal PNC were associated with higher odds of PTB compared to adequate PNC (adjusted odds ratios [aOR 6.21], 95% confidence interval [CI] 5.84–6.60; aOR 3.57, 95% CI 3.36–3.79). Inadequate PNC was associated with higher odds of PTB over time (effect modification p < 0.0001). Inadequate PNC was associated with 5.4 times higher odds of PTB in 1998, 7.0 times in 2008, and 9.1 times in 2018.

Conclusion Despite an increase in adequate PNC, there was a rise in PTB associated with inadequate and suboptimal PNC. PNC utilization was a stronger risk factor in recent years with higher PTB in patients who attended more than five PNC visits.

Key Points

目的 研究表明产前护理 (PNC) 与早产 (PTB) 之间存在关联。我们评估了 PTB 的趋势以及 PNC 和 PTB 的关联。

研究设计 这是一项针对 1991 年至 2018 年单胎、可行的非异常分娩的回顾性队列研究。世界卫生组织使用就诊次数定义 PNC 利用率：充足 (≥8)、次优 (5-7) 和不足 (<5) ）。主要结局是 PTB。趋势检验用于评估 PTB 随时间的变化。比较基线特征和结果。 Logistic 回归估计了 PNC 和 PTB 的关联。我们根据出生年份评估了效果修改。

结果 在 92,294 名患者中，14,057 名 (15%) 患有 PTB。与充分的 PNC 相比，不充分和次优的 PNC 与较高的 PTB 几率相关（调整后的比值比 [aOR 6.21]，95% 置信区间 [CI] 5.84–6.60；aOR 3.57，95% CI 3.36–3.79）。随着时间的推移，PNC 不足与较高的 PTB 几率相关（效应修正p  < 0.0001）。 PNC 不足与 1998 年 PTB 发生率高出 5.4 倍、2008 年高出 7.0 倍、2018 年高出 9.1 倍相关。

结论 尽管充足的 PNC 有所增加，但与 PNC 不足和次优相关的 PTB 却有所增加。近年来，PNC 的使用是一个更强的风险因素，参加超过 5 次 PNC 就诊的患者 PTB 较高。

关键点