Table 1.

Evidence map of direction of effect, strength of association and certainty of the evidence.

	PE			SGA		LBW		PTB		Stillbirth			Maternal Mortality
Nutritional supplements
Vitamin A	N/A			RR 1.00 (0.98–1.03, I2 = 0%, 3 studies, n = 14,694) ●●●		RR 0.92 (0.75–1.13, I2 = 51%, 6 studies, n = 16,214) ●●		RR 0.98 (0.94–1.01, I2 = 20%, 6 studies, n = 40,788) ●●●		RR 0.97 (0.92–1.03, I2 = 0%, 4 studies, n = 140,145) ●●●			RR 0.82 (0.56–1.19, I2 = 62%, 5 studies, n = 161,474) ●●
Vitamin B6	RR 1.71 (0.85–3.45, I2 N/A, 2 studies, n = 1197) ●●			N/A		N/A		N/A		N/A			N/A
Vitamin C and/or E	RR 0.96 (0.89–1.04, I2 33%, 19 studies, n = 24,819) ●●			RR 0.96 (0.89–1.03, I2 24%, 13 studies, n = 21,964) ●●●		RR 0.93 (0.73–1.19, I2 86%, 7 studies, n = 14,356) ●●		RR 1.00 (0.90–1.11, I2 53%,17 studies, n = 23,687) ●●		RR 1.21 (0.92–1.58, I2 0%, 9 studies, n = 19,908) ●●●			RR 0.60 (0.14–2.52, I2 0%, 6 studies, n = 17,574) ●●●
Vitamin D	RR 0.62 (0.43–0.91, I2 0%, 12 studies, n = 1353) ●●●●			RR 0.59 (0.39–0.88, I2 0%, 5 studies, n = 726) ●●		RR 0.76 (0.54–1.06, I2 64%, 6 studies, n = 792) ●●		RR 0.70 (0.49–1.00, I2 39%, 17 studies, n = 4019) ●●●		RR 0.62 (0.19–2.00, I2 0%, 5 studies, n = 860) ●●●			N/A
Vitamin D and calcium	RR 0.49 (0.31–0.77, I2 0%, 3 studies, n = 1120) ●●●●			RR 0.90 (0.58–1.38, I2 NA, 1 study, n = 660) ●●		RR 0.63 (0.12–3.24, I2 16%, 2 studies, n = 107) ●●		RR 1.53 (1.02–2.30, I2 0%, 6 studies, n = 988) ●●●		N/A			N/A
Calcium	RR 0.52 (0.41–0.65, I2 67%, 24 studies, n = 27,442) ●●			RR 1.01 (0.83–1.23, I2 20%, 9 studies, n = 6407) ●●●		RR 0.84 (0.73–0.96, I2 43%, 11 studies, n =7800) ●●●		RR 0.53 (0.33–0.86, I2 95%, 18 studies, n = 14,078) ●●		RR 0.55 (0.24–1.23, I2 75%, 7 studies, n = 10,687) ●●			RR 0.59 (0.18–1.92, I2 40%, 5 studies, n = 10,057) ●●●
Iodine	N/A			RR 1.26 (0.77–2.05, I2 0%, 2 studies, n = 377) ●●		RR 0.56 (0.26–1.20, I2 0%, 2 studies, n = 377) ●●		RR 0.71 (0.30–1.66, I2 32%, 2 studies, n = 376) ●●		N/A			N/A
Iron and/or folic acid	RR 0.99 (0.67–1.47, I2 0%, 6 studies, n = 4454) ●●			RR 0.92 (0.80–1.06, I2 67%, 7 studies, n = 8507 ●●		RR 0.87 (0.77–0.98, I2 27%, 13 studies, n = 22,946) ●●●		RR 0.97 (0.89–1.06, I2 0%, 15 studies, n = 24,420) ●●●		RR 0.88 (0.66–1.17, I2 0%, 7 studies, n = 16,891) ●●●			N/A
Magnesium	RR 0.87 (0.58–1.32, I2 0%, 3 studies, n = 1042) ●●●			RR 0.76 (0.54–1.07, I2 7%, 3 studies, n = 1291) ●●●		RR 0.95 (0.83–1.09, I2 22%, 5 studies, n = 5577) ●●●		RR 0.89 (0.69–1.14, I2 37%, 7 studies, n = 5981) ●●●		RR 0.73 (0.43–1.25, I2 0%, 4 studies, n = 5526) ●●			N/A
Zinc	RR 1.31 (0.82–2.10, I2 39%, 5 studies, n = 2518) ●●			RR 1.03 (0.95–1.11, I2 28%, 8 studies, n =4334) ●●●		RR 1.05 (0.94–1.17, I2 26%, 12 studies, n = 5545) ●●		RR 0.86 (0.76–0.97, I2 17%, 16 studies, n = 7563) ●●●		RR 0.20 (0.01–4.12, I2 NA, 2 studies, n = 376) ●●			RR 0.31 (0.01–7.43, I2 NA, 1 study, n = 85) ●●
Garlic	RR 0.78 (0.31–1.93, I2 N/A, 1 study, n = 100) ●●			N/A		N/A		N/A		N/A			N/A
Multiple micronutrients	RR 0.40 (0.27–0.59, I2 0%, 2 studies, n = 510) ●●			RR 0.88 (0.82–0.95, I2 59%, 16 studies, n = 39,696) ●●●		RR 0.87 (0.85–0.90, I2 22%, 20 studies, n = 70,293) ●●●●		RR 0.93 (0.85–1.02, I2 74%, 17 studies, n = 87,731) ●●		RR 1.09 (0.89–1.34, I2 75%, 20 studies, n = 11,4385) ●●			RR 1.17 (0.82–1.67, I2 0%, 8 studies, n = 84,081) ●●●
Lipid-based nutrients	N/A			RR 0.93 (0.88–0.98, I2 0%, 4 studies, n = 4828) ●●●●		RR 0.89 (0.82–0.98, I2 0%, 5 studies, n = 5851) ●●●●		RR 0.99 (0.86–1.14, I2 0%, 5 studies, n = 6072) ●●●		RR 1.06 (0.60–1.87, I2 55%, 4 studies, n = 6778) ●●			RR 0.52 (0.12–2.28, I2 0%, 3 studies, n = 5628) ●●●
Balanced protein-energy	RR 1.48 (0.82–2.66, I2 N/A, 2 study, n = 463) ●●			RR 0.79 (0.69–0.90, I2 16%, 7 studies, n = 4408) ●●●		N/A		RR 0.96 (0.80–1.16, I2 0%, 5 studies, n = 3374) ●●		RR 0.60 (0.39–0.94, I2 10%, 5 studies, n = 3408) ●●●			N/A
High protein	N/A			RR 1.58 (1.03–2.41, I2 N/A, 1 study, n = 505) ●●		N/A		N/A		RR 0.81 (0.31–2.15, I2 NA, 1 study, n = 529) ●●			N/A
Calf blood extract	N/A			RR 0.54 (0.20–1.47, I2 N/A, 1 study, n = 31)		N/A		N/A		N/A			N/A
Glucose	N/A			RR 1.11 (0.64–1.92, I2 N/A, 1 study, n = 30) ●		N/A		N/A		N/A			N/A
Galactose	N/A			RR 0.78 (0.39–1.54, I2 N/A, 1 study, n = 30) ●		N/A		N/A		N/A			N/A
Omega-3	RR 0.87 (0.71–1.07, I2 9%, 18 studies, n = 7166) ●●●			RR 1.01 (0.90–1.13, I2 0%, 8 studies, n = 6907) ●●●		RR 0.87 (0.79–0.96, I2 28%, 16 studies, n = 7940) ●●●●		RR 0.85 (0.76–0.95, I2 13%, 28 studies, n = 10,524) ●●●●		RR 0.89 (0.58–1.37, I2 32%, 13 studies, n = 7547) ●●			N/A
Dietary interventions
Salt restriction	RR 1.11 (0.46–2.66, I2 0%, 2 studies, n = 603) ●●			RR 1.50 (0.73–3.07, I2 NA, 1 study, n = 242) ●●		N/A		RR 1.08 (0.46–2.56, I2 NA, 1 study, n = 242) ●●		N/A			N/A
Caffeine restriction	N/A			RR 0.97 (0.57–1.64, I2 NA, 1 study, n = 1150) ●●		N/A		RR 0.81 (0.48–1.37, I2 NA, 1 study, n = 1153) ●●		N/A			N/A
Antenatal dietary counselling	RR 0.97 (0.84–1.14, I2 6%, 15 studies, n = 8087) ●●●			RR 1.15 (0.94–1.41, I2 0%, 10 studies, n = 5529) ●●●		RR 0.54 (0.17–1.71, I2 84%, 4 studies, n = 2271) ●●		RR 0.72 (0.61–0.86 I2 21%, 14 studies, n = 7612) ●●●●		RR 0.63 (0.28–1.40, I2 0%, 6 studies, n = 5631) ●●●			RR 1.08 (0.07–17.32, I2 NA, 1 study, n = 2122) ●●
LEGEND Direction of effect and strength of association
Benefit—Strong effect (RR < 0.40)		Benefit—Moderate effect (RR 0.40–0.69)			Benefit—Weak effect (RR 0.70–0.89)				Benefit—Not discernible (RR 0.90–0.99)			No significant effect (95% CI crosses 1.00)
Harm—Not discernable (RR 1.01–1.09)		Harm—Weak effect (RR 1.10–1.49)			Harm—Moderate effect (RR 1.50–2.99)				Harm—Strong effect (RR ≥ 3.00)			Not available
Certainty of the evidence
High ●●●●			Moderate ●●●				Low ●●				Very low ●

PE—pre-eclampsia; SGA—small-for-gestational age; LBW—low birth weight; PTB—preterm birth.