Table 3 Results of primary and subgroup meta-analyses by outcome

NICU admission all

[25, 37, 39, 51, 52, 54,55,56, 60, 62, 63, 65, 68, 69]

Linear dose-response^a

0.63

0.56–0.71

Neonatal death

[37, 40, 62, 65]

U-Shape^b

< 39: 0.59

≥39: 2.09

0.43–0.83

1.18–3.70

Respiratory morbidity

[51, 53, 55, 57, 58, 61, 64, 65, 68]

Linear dose-response^a

0.64

0.51–0.79

Hospitalization ≥5 days

[38, 62, 65, 68, 69]

U-Shape^b

< 39 0.52

≥39 2.00

0.36–0.75

1.40–2.86

Sepsis

[37, 52, 65, 68]

U-Shape^b

< 39 0.55

≥39 3.57

0.44–0.67

1.87–6.78

Hypoglycemia

[25, 38, 60, 65, 68, 69]

Linear dose-response^a

0.84

0.79–0.91

Apgar Score < 7

[39, 56, 60, 65, 69]

Linear dose-response^a

0.90

0.69–1.17

Jaundice

[56, 60, 65, 68, 69]

Linear dose-response^a

0.71

0.66–0.77

Respiratory distress syndrome

[37, 59, 60, 65, 69]

Linear dose-response^a

0.60

0.54–0.67

Transient tachypnea of the newborn

[37, 55, 59, 60, 65]

Linear dose-response^a

0.68

0.54–0.86

Pneumothorax

[44, 59, 60, 67]

Binary (37 + 38 WG vs. ≥39 WG)^c

0.99

0.03–39.19

Maternal hysterectomy

[37, 52]

Binary (37 + 38 WG vs. ≥39 WG)^c

1.10

0.03–39.35

Maternal blood transfusion

[37, 60]

Binary (37 + 38 WG vs. ≥39 WG)^c

1.21

0.02–65.67

 NICU admission only ERCS

[37, 39, 54, 60]

Linear dose-response^a

0.66

0.65–0.67

 NICU death only repeat CS

[37, 40]

U-Shape^b

< 39 0.67

≥39 1.68

0.51–0.87

1.07–2.65