Centre of Public Health Sciences, Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
Faculty of Medicine, University of Iceland, Reykjavík, Iceland.
Birth. 2020 Mar;47(1):105-114. doi: 10.1111/birt.12467. Epub 2019 Nov 19.
The frequency of preterm births has been increasing globally, mainly due to a rise in iatrogenic late preterm births. The aim of this study was to assess the prevalence of preterm births in Iceland during 1997-2016 by type of preterm birth.
This study included all live births in Iceland during 1997-2016 identified from the Icelandic Medical Birth Registry. Risk of preterm birth by time period was assessed with Poisson regression models adjusted for demographic variables and indications for iatrogenic births.
The study population included 87 076 infants, of which 4986 (5.7%) were preterm. The preterm birth rate increased from 5.3% to 6.1% (adjusted rate ratio [ARR] = 1.16, confidence interval [CI] = 1.07-1.26) between 1997-2001 and 2012-2016 overall. The increase was only evident in multiples (ARR 1.41, 95% CI 1.21-1.65), not singletons (1.07, 0.97-1.19). The rate of late preterm births (34-36 weeks) increased significantly (1.24, 1.14-1.40), and the rate of iatrogenic preterm births more than doubled during this period even after adjustment for identified medical indications (2.40, 2.00-2.88). The rate of spontaneous preterm births decreased during the study period (0.63, 0.55-0.73), and the rate of PPROM increased (1.31, 1.09-1.57). The most common contributing indications for iatrogenic births were fetal distress (26.2%), hypertensive disorders (18.2%), and severe preeclampsia (16.9%).
Preterm birth rates increased in multiples in Iceland between 1997 and 2016, and late and iatrogenic preterm births increased overall. The increase in iatrogenic preterm births remained significant after adjusting for medical indications, suggesting that other factors might be affecting the rise.
全球范围内，早产的发生率一直在上升，主要是由于医源性晚期早产的增加。本研究旨在评估 1997 年至 2016 年冰岛早产的发生率，并按早产类型进行分类。
本研究纳入了 1997 年至 2016 年期间冰岛所有的活产儿，这些信息均来自冰岛医学出生登记处。通过泊松回归模型评估不同时间段早产的风险，并根据人口统计学变量和医源性分娩的指征进行了调整。
研究人群包括 87076 名婴儿，其中 4986 名（5.7%）为早产儿。总体而言，早产率从 1997-2001 年至 2012-2016 年期间从 5.3%增加到了 6.1%（调整后的比率比 [ARR]为 1.16，95%置信区间 [CI]为 1.07-1.26）。这种增加仅见于多胎（ARR 1.41，95%CI 1.21-1.65），而非单胎（1.07，0.97-1.19）。晚期早产（34-36 周）的发生率显著增加（1.24，1.14-1.40），即使在考虑到已确定的医学指征后，医源性早产的发生率也在这期间翻了一番以上（2.40，2.00-2.88）。在此期间，自发性早产的发生率有所下降（0.63，0.55-0.73），而胎膜早破（PPROM）的发生率增加（1.31，1.09-1.57）。医源性分娩最常见的指征包括胎儿窘迫（26.2%）、高血压疾病（18.2%）和严重子痫前期（16.9%）。
1997 年至 2016 年期间，冰岛多胎的早产率有所上升，晚期和医源性早产的发生率总体上升。在调整了医学指征后，医源性早产的增加仍然显著，这表明可能还有其他因素在影响早产率的上升。
