The Association of Inflammatory Biomarker of Neutrophil-to-Lymphocyte Ratio with Spontaneous Preterm Delivery: A Systematic Review and Meta-analysis

Table 1

Characteristics of included studies assessing the association between NLR and preterm delivery.

Authors	Publication year	Country	Sample size (case/control)	Study type	Defined preterm delivery	Mean age of cases	Quality assessment
Akgun et al. [22]	2017	Turkey	238/545	Prospective case-control	37 weeks		High
Akkar et al. [25]	2016	Turkey	35/44	Prospective case-control	37 weeks		Low
Cha et al. [29]	2020	South Korea	28/308	Prospective case-control	37 weeks		High
Daglar et al. [17]	2016	Turkey	30/53	Prospective case-control	37 weeks		Low
Farzaneh et al. [24]	2019	Iran	109/110	Cross-sectional	37 weeks		Low
Gezer et al. [28]	2018	Turkey	229/178	Retrospective case-control	37 weeks		High
Isik et al. [16]	2015	Turkey	90/128	Retrospective case-control	34 weeks		High
Kim et al. [27]	2011	South Korea	102/73	Retrospective case-control	37 weeks		High
Ma et al. [15]	2020	China	105/210	Retrospective case-control	37 weeks		High
Melissa et al. [19]	2018	USA	137/145	Retrospective case-control	37 weeks		Low
Mubark et al. [21]	2015	Iraq	30/50	Prospective case-control	37 weeks		Low
Ozel et al. [26]	2020	Turkey	50/47	Cross-sectional	37 weeks		High
Park et al. [23]	2019	South Korea	19/49	Retrospective cohort	34 weeks	34 [25-39]	High
Sabarudin et al. [20]	2016	Indonesia	33/33	Cross-sectional	37 weeks		Low
Tamer et al. [18]	2017	Turkey	74/45	Case-control	37 weeks		Low

Indirectly conceived from methods, median (range).