A scoping review of severe maternal morbidity: describing risk factors and methodological approaches to inform population-based surveillance

Korst, Lisa M.; Gregory, Kimberly D.; Nicholas, Lisa A.; Saeb, Samia; Reynen, David J.; Troyan, Jennifer L.; Greene, Naomi; Fridman, Moshe

doi:10.1186/s40748-020-00123-1

Maternal Health, Neonatology and Perinatology

Table 1 Summary of included studies with reference numbers. N = 81 [3, 8, 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94]

From: A scoping review of severe maternal morbidity: describing risk factors and methodological approaches to inform population-based surveillance

Study Characteristic	Reference Number
Number and data source of included studies
US^a data (n = 50)
National Inpatient Sample	17,18,26,39,45,48,58,72
National Readmission Database: 21 states	32
CMS^b Medicaid (MAX) data	22
US claims data	27,70
US perinatal data networks	28,43
Hospital discharge data: 7 states	33
Hospital discharge data: Illinois	84
Hospital discharge data: Maryland	81
Hospital discharge ± birth certificate data: New York State	19,44,53
Hospital discharge + birth certificate data: 3 states	29
Hospital discharge + birth certificate data: Iowa	38
Hospital discharge + birth certificate data: New York City	46,47,49,50,78
Hospital discharge, birth, ± death certificate data: California	36,40,52,55-57,68,69,76
Hospital discharge, birth, + death certificate data: Georgia	91
Hospital discharge, birth, ± death certificate data: Washington	42,62–64
Hospital discharge + medical record data: 16 California hospitals	51
Hospital discharge + medical record data: Massachusetts	21
Hospital discharge + SART^c + vital statistics data: Massachusetts	23
Birth certificate data: Ohio	71
Birth certificate and SART data: 8 states	67
Medical record data single hospital: California	93
Medical record data single hospital: New York	73
Medical record data single hospital: Missouri	83
Medical record data single hospital: Tennessee	41
Non-US data (n = 31)
Multiple countries including US	60
Multiple countries not including US	90
Japan	16
Korea	75
Sweden	92
Finland	77
France	25,54,88
Canada: Ontario	34,35,80,89
Canada: British Columbia	61,85,86
Canada: multiple provinces	3,8,65,66,74,79,94
Australia: New South Wales	20,24,30,31,37,82,87
Australia: Victoria	59
Study design and population
Study design nested case-control (n = 6)
Yes	16,21,34,42,54,88
Hospital-level risk factors with specific hypotheses (n = 8)
Patient-level data adjusted for clustering among hospitals	19,27,29,32,39
Hierarchical models	36,91
Hospital-level data	49
Delivery discharges limited by: (n = 22)
Community hospitals	36
Annual delivery volume less than 1000	45
Low risk	19,40,65,66
Low risk breech presentation	24
Medicaid eligibility	22
Nulliparous	85
Prior cesarean delivery with parity = 1	94
Prior cesarean delivery ≥3	73
No prior cesarean delivery	66
Cesarean delivery 22–34 gestational weeks	25
Elective cesarean delivery	16
Preterm gestation	20,68
Term laboring patients with prolonged second stage	74
Preeclampsia	27
Hemorrhage	80
Race/ethnicity Hispanic or White	46
Race Black or White	47,48
SMM^ddefinition CDC^e basis [7] (n = 37)
25 indicators	17,18,23,29,33,36,38,42,46-53,58,60,68,69,71,72,75,76,91,93
18 indicators	19,26,27,41,44,55-57,78,83,84
SMM definition not using CDC basis (n = 44)
Adapted from other US work (Bateman et al. [22])	32,39,45,61–63
Adapted from Canadian work (Wen et al. [3]/Joseph et al. [8])	3,8,22,34,35,66,74,89,94
Adapted from Australian work (Roberts et al. [8])	20,24,30,31,37,59,79,82,87
Adapted from Swedish work (Wahlberg et al. [92])	90,92
Adapted from Geller et al. (5 factor) [95]	43,85
Death	80
Intensive care unit admission	21,25,28,40,53,65,67,71,73
Other	16,54,64,77,86,88
Sensitivity analysis for use of transfusion in SMM definition (n = 15)
Yes	26,33,38,44,46,47,49,50,55-57,60,78,91,94
Blood transfusion threshold was 4 units of packed red blood cells (n = 6)
Yes	43,51,54,85,88,93
Blood transfusion not included in definition (n = 10)
Yes	22,32,37,39,45,77,80,86,90,92
Key risk factors studied
General risk factors (no hypotheses) (n = 16)
Yes	3,8,22,38,42-45,52,53,59,60,80,81,83,90
Patient-level risk factors with specific hypotheses (n = 57)
Race/ethnicity	18,26,33,46-48,50,57,58,72
BMI^f or gestational weight gain	35,55,62,71,73,78,86,88
Maternal age	63,76,85
Preterm birth	25,51,68
Infertility/IVF^g/ART^h	23,34,54,67,70,93
Preeclampsia	64
Hemorrhage	37
Obstructive sleep apnea	28
Congenital heart disease	79
Inflammatory bowel disease	87
Autoimmunity	30
Idiopathic arthritis	31
Rural vs. urban	61
Maternal birthplace or immigration country	89,92
Amphetamine/opioid use	17
Route of delivery	20,21,24,41,56,66,74,77,84,94
Induction of labor	40,65,82
Anesthesia for cesarean delivery	16
Off-hours delivery	69,75
Hospital-level risk factors with specific hypotheses (n = 8)
Delivery volume	27,29,39
Level of care	32,91
Percent midwives delivering	19
Presence of laborist	36
Hospital quality indicators	49

^aUS United States; ^bCMS Centers for Medicare and Medicaid Services; ^cSociety for Assisted Reproductive Technology; ^dSMM severe maternal morbidity; ^eCDC Centers for Disease Control and Prevention; ^fBMI body mass index; ^gIVF in vitro fertilization; ^hART assisted reproductive technology

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ISSN: 2054-958X

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