Comparison 3. Dose (DHA/EPA) subgroups.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Preterm birth (< 37 weeks)	26	10294	Risk Ratio (M‐H, Fixed, 95% CI)	0.88 [0.80, 0.97]
1.1 Low: < 500 mg/day	6	1604	Risk Ratio (M‐H, Fixed, 95% CI)	0.88 [0.65, 1.20]
1.2 Mid: 500 mg‐1 g/day	9	4343	Risk Ratio (M‐H, Fixed, 95% CI)	0.79 [0.64, 0.98]
1.3 High: > 1 g/day	9	4240	Risk Ratio (M‐H, Fixed, 95% CI)	0.92 [0.83, 1.03]
1.4 Other	2	107	Risk Ratio (M‐H, Fixed, 95% CI)	0.66 [0.19, 2.32]
2 Early preterm birth (< 34 weeks)	9	5204	Risk Ratio (M‐H, Fixed, 95% CI)	0.58 [0.44, 0.77]
2.1 Low: < 500 mg/day	1	168	Risk Ratio (M‐H, Fixed, 95% CI)	0.29 [0.05, 1.51]
2.2 Mid: 500 mg‐1 g/day	7	4176	Risk Ratio (M‐H, Fixed, 95% CI)	0.47 [0.30, 0.75]
2.3 High: > 1 g/day	2	860	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.49, 0.99]
3 Prolonged gestation (> 42 weeks)	6	5141	Risk Ratio (M‐H, Fixed, 95% CI)	1.59 [1.10, 2.30]
3.1 Low: < 500 mg/day	2	303	Risk Ratio (M‐H, Fixed, 95% CI)	1.72 [0.07, 41.64]
3.2 Mid: 500 mg‐1 g/day	2	2544	Risk Ratio (M‐H, Fixed, 95% CI)	1.92 [0.54, 6.81]
3.3 High: > 1 g/day	3	2294	Risk Ratio (M‐H, Fixed, 95% CI)	1.56 [1.05, 2.30]
4 Pre‐eclampsia (hypertension with proteinuria)	20	8306	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.69, 1.01]
4.1 Low: < 500 mg/day	5	650	Risk Ratio (M‐H, Fixed, 95% CI)	0.59 [0.28, 1.26]
4.2 Mid: 500 mg‐1 g/day	7	4118	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.62, 1.11]
4.3 High: > 1 g/day	8	3479	Risk Ratio (M‐H, Fixed, 95% CI)	0.87 [0.66, 1.14]
4.4 Other	1	59	Risk Ratio (M‐H, Fixed, 95% CI)	2.07 [0.20, 21.60]
5 Caesarean section	28	8481	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.91, 1.03]
5.1 Low: < 500 g/day	8	1670	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.84, 1.06]
5.2 Mid: 500 mg‐1 g/day	10	4399	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.85, 1.02]
5.3 High: > 1 g/day	8	2294	Risk Ratio (M‐H, Fixed, 95% CI)	1.15 [0.97, 1.37]
5.4 Other	2	118	Risk Ratio (M‐H, Fixed, 95% CI)	0.59 [0.30, 1.15]
6 Length of gestation (days)	42	12517	Mean Difference (IV, Random, 95% CI)	1.67 [0.95, 2.39]
6.1 Low: < 500 mg/day	12	2117	Mean Difference (IV, Random, 95% CI)	1.05 [0.07, 2.03]
6.2 Mid: 500 mg‐1 g/day	15	4881	Mean Difference (IV, Random, 95% CI)	1.97 [0.56, 3.38]
6.3 High: > 1 g/day	12	3364	Mean Difference (IV, Random, 95% CI)	1.86 [0.45, 3.27]
6.4 Mixed	1	1998	Mean Difference (IV, Random, 95% CI)	0.10 [‐1.00, 1.20]
6.5 Other	3	157	Mean Difference (IV, Random, 95% CI)	2.24 [‐0.83, 5.31]
7 Perinatal death	10	7416	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.54, 1.03]
7.1 Low: < 500 mg/day	2	1127	Risk Ratio (M‐H, Fixed, 95% CI)	0.52 [0.20, 1.33]
7.2 Mid: 500 mg‐1 g/day	3	2566	Risk Ratio (M‐H, Fixed, 95% CI)	0.41 [0.16, 1.02]
7.3 High: > 1 g/day	5	3723	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.61, 1.29]
8 Stillbirth	16	7880	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.62, 1.42]
8.1 Low: < 500 mg/day	1	977	Risk Ratio (M‐H, Fixed, 95% CI)	0.67 [0.11, 3.96]
8.2 Mid: 500 mg/day‐1 g/day	5	2783	Risk Ratio (M‐H, Fixed, 95% CI)	0.70 [0.27, 1.83]
8.3 High: > 1 g/day	7	3933	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.62, 1.69]
8.4 Other	3	187	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.23, 5.94]
9 Neonatal death	9	7448	Risk Ratio (M‐H, Fixed, 95% CI)	0.61 [0.34, 1.11]
9.1 Low: < 500 mg/day	2	1123	Risk Ratio (M‐H, Fixed, 95% CI)	0.47 [0.15, 1.44]
9.2 Mid: 500 mg/day‐1 g/day	2	2700	Risk Ratio (M‐H, Fixed, 95% CI)	0.50 [0.12, 1.98]
9.3 High: > 1 g/day	5	3625	Risk Ratio (M‐H, Fixed, 95% CI)	0.78 [0.34, 1.78]
10 Low birthweight (< 2500 g)	15	8449	Risk Ratio (M‐H, Fixed, 95% CI)	0.90 [0.82, 0.99]
10.1 Low: < 500 mg/day	5	1551	Risk Ratio (M‐H, Fixed, 95% CI)	0.74 [0.51, 1.08]
10.2 Mid: 500 mg‐1 g/day	5	3901	Risk Ratio (M‐H, Fixed, 95% CI)	0.71 [0.54, 0.92]
10.3 High: > 1 g/day	5	2997	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.88, 1.08]
11 Small‐for‐gestational age/IUGR	8	6907	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.90, 1.13]
11.1 Low: < 500 mg/day	1	973	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.73, 1.48]
11.2 Mid: 500 mg‐1 g/day	2	3369	Risk Ratio (M‐H, Fixed, 95% CI)	0.85 [0.66, 1.09]
11.3 High: > 1 g/day	4	2506	Risk Ratio (M‐H, Fixed, 95% CI)	1.07 [0.93, 1.23]
11.4 Other	1	59	Risk Ratio (M‐H, Fixed, 95% CI)	2.07 [0.20, 21.60]
12 Birthweight (g)	44	11584	Mean Difference (IV, Random, 95% CI)	75.30 [38.09, 112.50]
12.1 Low: < 500 mg/day	12	2220	Mean Difference (IV, Random, 95% CI)	26.32 [‐12.74, 65.39]
12.2 Mid: 500 mg‐1 g/day	18	5007	Mean Difference (IV, Random, 95% CI)	91.49 [24.34, 158.64]
12.3 High: > 1 g/day	14	4298	Mean Difference (IV, Random, 95% CI)	88.31 [29.61, 147.01]
12.4 Other	1	59	Mean Difference (IV, Random, 95% CI)	‐203.20 [‐456.97, 50.57]