Table 1.

Summary of included systematic reviews and settings of primary studies included in the review

Interventions	Number of reviews	Number of primary studies	Country NR	Country of primary study					Studies where setting NK
				LI	LM	UM	HI	Mixed
Primary prevention interventions
Health systems
Models of antenatal care delivery (group/specialised)61–71	11	68	2	0	2	2	64	0	0
Midwifery led care72	1	15	0	0	0	0	15	0	0
Improving ANC coverage28	1	34	0	10	15	5	0	0	0
Health behaviours
Smoking cessation35 73	2	111	0	0	0	1	110	0	0
Weight management21 74–78	6	70	1	0	2	8	60	0	0
Nutritional interventions
Macronutrient supplements29 30	2	34	0	3	9	10	8	4	0
Micronutrient supplements21 27–31 35–40 67–86	33	481	2	29	82	122	214	6	9
Vitamin D27 31 36 79–81	6	75
Vitamin A37 82	2	24
Vitamin E, C, E and C38 39 83	3	67
Iron, folic acid, iron and folic acid40 84–90	8	182
Fish oil91–95	5	38
Zinc32 96	2	25
Calcium41 42	2	27
Iodine97	2	14
Multiple micronutrients43 44 98	3	29
Screening and treatment of periodontal disease 99–110	12	46	0	0	3	7	36	0	0
Screening and prevention/treatment of infection	14	91	2	2	2	6	79	0	2
Asymptomatic bacteriuria23 111–113	4
Screening and antibiotics for syphilis24	1
Influenza vaccine114 115	2
Lower genital tract infection26	1
UTI116 117	2
Vaginal candidiasis25	1
Non-specific infection118 119	2
Malaria33 120 121	3	17	0	8	7	2	2	0	0
Secondary prevention interventions
Cerclage18 22 45 122–136	18	123	10	0	7	11	42		51
Bed rest137–139	3	40	1	4	0	0	36	0	0
Cervical pessary140–145	6	16	0	0	0	1	14	1	0
Progesterone19 20 146–159	16	59	5	1	7	8	28	4	11
Tocolytics160–172	11	167	3	1	0	13	68	0	84

ANC, antenatal care; HI, high income; LI, low income; LM, low middle; NK, not known; NR, not reported; UM, upper middle; UTI, urinary tract infection.