Table 3 Quality assessment of included studies
From: Spiral artery blood flow during pregnancy: a systematic review and meta-analysis
Domain | Items for consideration | Alouini (ref. [20]) | Coppens (ref. [21]) | Deurloo (ref. [2]) | Deurloo (ref. [22]) | Hsieh (ref. [23]) | Kurjak (ref. [24]) | Kurjak (ref. [25]) | Mäkikallio (ref. [26]) | Mäkikallio (ref. [27]) | Matijevic (ref. [9]) | Ozkan (ref. [15]) | Ozkaya (ref. [28]) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Study participation | Adequate description of participants’ characteristics |  |  |  |  |  |  |  |  |  |  |  |  |
• Parity or gravidity | – | – | – | + | + | – | – | + | – | – | – | + | |
• Health or comorbidities of participants | – | – | + | + | + | – | + | + | – | – | – | – | |
• Clear reporting of weeks amenorrhea | + | + | + | + | + | + | + | + | + | + | + | + | |
• Ethnicity | – | – | – | – | – | – | – | – | – | – | – | – | |
• Age | – | – | + | + | + | – | + | + | + | + | + | + | |
• Non-pregnant weight/BMI | – | – | + | + | – | – | – | – | – | – | – | – | |
• Use of medication or supplements | – | – | – | – | – | – | + | – | – | – | – | – | |
Adequate description of participant recruitment | – | – | + | + | + | – | + | – | + | + | + | + | |
Adequate description of inclusion and exclusion criteria | – | – | + | + | + | + | + | + | + | – | + | + | |
Study attrition | Reasons for loss to follow-up/drop-out are provided | – | + | – | – | – | – | – | – | – | – | – | – |
Adequate description of participants lost to follow-up/ differences between participants who completed and drop-outs | – | – | – | – | – | – | – | – | – | – | – | – | |
Outcome measurement | Method of measurement is adequately valid and reliable | + | + | + | + | + | + | + | + | + | + | + | + |
The methods and setting are the same for all study participants and throughout follow up | + | + | + | + | + | – | + | + | + | + | + | + | |
Data reporting | Data is extractable as mean with standard deviation for analysis | + | + | + | + | + | + | + | + | + | + | + | + |
Study design | Study used a longitudinal study design | – | + | + | + | + | + | – | + | + | – | – | – |
Multiple (> 2) longitudinal pregnant measurements during pregnancy of the variable | ? | + | + | + | + | + | ? | + | + | ? | ? | ? | |
Assessment of intra- and/or inter-observer variation is performed | – | – | + | + | – | – | – | + | + | – | – | – | |
Count (+) | 4 | 7 | 12 | 13 | 11 | 5 | 9 | 11 | 10 | 6 | 7 | 8 | |
Score % | 24 | 41 | 71 | 76 | 65 | 29 | 53 | 65 | 59 | 35 | 41 | 47 | |
Quality | Low | Medium | High | High | High | Low | Medium | High | Medium | Low | Medium | Medium |