Table 6.
Level of evidence for the association of perinatal factors and psychotic disorders
| Factor | k |
Random‐effects measure, ES (95% CI) |
Features used for classification of level of evidence | eOR | CE | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | p random‐effects | I2 (p) | PI (95% CI) | SSE/ESB | LS | |||||
| Winter/spring season of birth in Northern hemisphere79 | 27 | OR, 1.04 (1.02‐1.06) | 115,010 | 2.1 × 10−6 | 0% (0.99) | 1.02‐1.06 | No/No | Yes | 1.04 | III |
| Diabetes in pregnancy37 | 2 | OR, 10.12 (1.84‐55.72) | 243 | 0.008 | 0% (0.69) | NA | NA/NA | No | 10.12 | IV |
| Emergency caesarean section37 | 3 | OR, 3.36 (1.48‐7.63) | 825 | 0.004 | 0% (0.92) | 0.02‐685.69 | No/No | No | 3.36 | IV |
| Birth weight <2000 g37 | 2 | OR, 2.46 (1.11‐5.46) | 507 | 0.027 | 0% (0.85) | NA | NA/NA | Yes | 2.46 | IV |
| Congenital malformations36, 37 | 10 | OR, 2.31 (1.29‐4.13) | 1,080 | 0.005 | 0% (0.99) | 1.16‐4.57 | No/Yes | Yes | 2.31 | IV |
| Incubator or resuscitation36 | 8 | OR, 2.12 (1.29‐3.47) | 438 | 0.003 | 0% (0.85) | 1.14‐3.92 | No/No | No | 2.12 | IV |
| Neonatal vitamin D (<19.7 vs. 40.5‐50.9 nmol/L)50 | 1 | RR, 2.11 (1.28‐3.49) | 424 | 0.004 | NA (1.00) | NA | NA/NA | Yes | 2.11 | IV |
| Neonatal vitamin D (30.9‐40.4 vs. 40.5‐50.9 nmol/L)50 | 1 | RR, 2.10 (1.30‐3.40) | 424 | 0.003 | NA (1.00) | NA | NA/NA | Yes | 2.10 | IV |
| Threatened premature delivery37 | 2 | OR, 2.05 (1.02‐4.10) | 314 | 0.043 | 0% (0.56) | NA | NA/NA | Yes | 2.05 | IV |
| Neonatal vitamin D (19.7‐30.9 vs. 40.5‐50.9 nmol/L)50 | 1 | RR, 2.02 (1.27‐3.19) | 424 | 0.003 | NA (1.00) | NA | NA/NA | Yes | 2.02 | IV |
| Pre‐pregnancy and pregnancy maternal obesity82 | 4 | OR, 1.99 (1.26‐3.14) | 305 | 0.003 | 27% (0.24) | 0.47‐8.50 | No/No | No | 1.99 | IV |
| Uterine atony37 | 3 | OR, 1.93 (1.35‐2.76) | 836 | 3.3 × 10−4 | 0% (0.37) | 0.19‐19.78 | No/No | Yes | 1.93 | IV |
| Obstetric complications81 | 10 | OR, 1.84 (1.25‐2.70) | 373 | 0.002 | 25% (0.21) | 0.80‐4.22 | Yes/Yes | No | 1.84 | IV |
| Neonatal vitamin D (>50.9 vs. 40.5‐50.9 nmol/L)50 | 1 | RR, 1.71 (1.04‐2.80) | 424 | 0.033 | NA (1.00) | NA | NA/NA | Yes | 1.71 | IV |
| Antepartum haemorrhage36, 37 | 14 | OR, 1.63 (1.12‐2.38) | 1,489 | 0.011 | 6% (0.38) | 0.92‐2.89 | No/No | No | 1.63 | IV |
| Birth weight <2500 g36, 37 | 13 | OR, 1.57 (1.20‐2.07) | 1,815 | 0.001 | 0% (0.45) | 1.16‐2.14 | No/Yes | Yes | 1.57 | IV |
| Small head circumference37 | 2 | OR, 1.41 (1.00‐1.97) | 762 | 0.048 | 0% (0.58) | NA | NA/NA | No | 1.41 | IV |
| Placental abruption37 | 2 | OR, 4.54 (0.32‐64.63) | 314 | 0.264 | 72% (0.05) | NA | NA/NA | No | 4.54 | ns |
| Rhesus incompatibility36, 37 | 9 | OR, 1.96 (0.88‐4.33) | 1,097 | 0.098 | 0% (0.98) | 0.75‐5.11 | No/NA | No | 1.96 | ns |
| Asphyxia37 | 3 | OR, 1.95 (0.77‐4.97) | 1,122 | 0.160 | 76% (0.01) | 0‐108727 | No/No | Yes | 1.95 | ns |
| Forceps delivery36 | 9 | OR, 1.67 (0.90‐3.08) | 554 | 0.103 | 42% (0.08) | 0.34‐8.15 | Yes/No | Yes | 1.67 | ns |
| Rubella or syphilis36 | 9 | OR, 1.64 (0.47‐5.71) | 567 | 0.435 | 0% (0.099) | 0.37‐7.39 | No/No | No | 1.64 | ns |
| Twin birth36 | 9 | OR, 1.53 (0.79‐2.97) | 558 | 0.208 | 0% (0.45) | 0.69‐3.40 | Yes/No | No | 1.53 | ns |
| Gestational age <37 weeks36, 37 | 7 | OR, 1.35 (0.99‐1.84) | 1,502 | 0.057 | 0% (0.66) | 0.90‐2.03 | Yes/No | No | 1.35 | ns |
| Being small for gestational age37 | 5 | OR, 1.34 (0.82‐2.19) | 1,436 | 0.240 | 58% (0.04) | 0.28‐6.41 | No/No | Yes | 1.34 | ns |
| Smoking in pregnancy37 | 1 | OR, 1.29 (0.72‐2.31) | 76 | 0.393 | NA (1.00) | NA | NA/NA | No | 1.29 | ns |
| Birth weight <2500 g and prematurity37 | 4 | OR, 1.25 (0.52‐3.00) | 959 | 0.610 | 65% (0.03) | 0.03‐46.31 | No/No | Yes | 1.25 | ns |
| Anaemia in pregnancy37 | 3 | OR, 1.22 (0.46‐3.28) | 528 | 0.688 | 56% (0.10) | 0‐ 41770 | No/No | No | 1.22 | ns |
| Maternal stress during pregnancy106 | 5 | RR, 1.16 (0.94‐1.43) | 4,412 | 0.166 | 71% (0.01) | 0.60‐2.25 | No/No | No | 1.16 | ns |
| Low Apgar score37 | 2 | OR, 1.13 (0.69‐1.84) | 405 | 0.622 | 0% (0.67) | NA | NA/NA | No | 1.13 | ns |
| Preeclampsia36, 37 | 15 | OR, 1.07 (0.78‐1.46) | 2,277 | 0.690 | 22% (0.20) | 0.53‐2.15 | No/No | Yes | 1.07 | ns |
| Forceps/vacuum delivery37 | 7 | OR, 1.07 (0.81‐1.42) | 1,888 | 0.643 | 34% (0.16) | 0.55‐2.09 | No/No | Yes | 1.07 | ns |
| Cord complications36 | 9 | OR, 1.06 (0.47‐2.39) | 549 | 0.894 | 0% (0.54) | 0.40‐2.83 | No/No | No | 1.06 | ns |
| Small birth length37 | 3 | OR, 1.05 (0.86‐1.30) | 929 | 0.619 | 0% (0.91) | 0.28‐4.03 | No/No | No | 1.05 | ns |
| Baby detained in hospital37 | 3 | OR, 1.04 (0.59‐1.86) | 976 | 0.883 | 76% (0.01) | 0‐903.90 | No/No | Yes | 1.04 | ns |
| Winter/spring season of birth in Southern hemisphere80 | 7 | OR, 1.03 (0.88‐1.19) | 15,023 | 0.738 | 16% (0.30) | 0.77‐1.37 | No/NA | No | 1.03 | ns |
| Influenza during pregnancy40, 41 | 14 | OR, 0.99 (0.91‐1.08) | 7,620 | 0.867 | 46% (0.03) | 0.79‐1.24 | No/No | No | 0.99 | ns |
| Non‐vertex presentation36, 37 | 15 | OR, 0.99 (0.75‐1.31) | 2,272 | 0.953 | 6% (0.38) | 0.65‐1.51 | No/No | No | 0.99 | ns |
| Gestational age >42 weeks37 | 3 | OR, 0.97 (0.48‐1.95) | 1,193 | 0.933 | 42% (0.18) | 0‐1000 | No/No | No | 0.97 | ns |
| Caesarean section36, 37 | 15 | OR, 0.95 (0.71‐1.28) | 1,920 | 0.734 | 0% (0.46) | 0.68‐1.32 | No/No | No | 0.95 | ns |
| Breech delivery37 | 3 | OR, 0.95 (0.49‐1.84) | 470 | 0.879 | 0% (0.78) | 0.01‐68.26 | No/No | No | 0.95 | ns |
| Urinary infection in pregnancy37 | 3 | OR, 0.90 (0.44‐1.84) | 690 | 0.776 | 29% (0.24) | 0‐498.73 | No/No | No | 0.90 | ns |
| Induction of labor37 | 3 | OR, 0.82 (0.53‐1.28) | 528 | 0.387 | 24% (0.26) | 0.02‐35.30 | No/No | No | 0.82 | ns |
| Cephalopelvic disproportion37 | 2 | OR, 0.60 (0.18‐1.99) | 243 | 0.407 | 0% (0.48) | NA | NA/NA | No | 0.60 | ns |
| Labour >24 hours36 | 4 | OR, 0.84 (0.39‐1.78) | 266 | 0.643 | 20% (0.28) | 0.09‐8.11 | No/No | No | 0.84 | ns |
k – number of samples for each factor, ES – effect size, N – number of cases, PI – prediction interval, CI – confidence interval, SSE – small‐study effect, ESB – excess significance bias, LS – largest study with significant effect, eOR – equivalent odds ratio, CE – class of evidence, IRR – incidence rate ratio, OR – odds ratio, RR – relative risk, NA – not assessable, ns – not significant