Table 1.

Prenatal, perinatal and neonatal characteristics of children who completed the INTER-NDA in the INTERGROWTH-21st Project compared with those lost to follow-up

Prenatal, perinatal and neonatal characteristics	Children contributing to INTERGROWTH-21st international INTER-NDA standards (n=1209)	Children lost to follow-up (n=331)
	Mean (SD) or number (%)	Mean (SD) or number (%)
Maternal age at recruitment, years	28.4 (3.8)	27.4 (4.3)
Maternal body-mass-index, kg/m2	23.2 (3.0)	23.6 (2.8)
Multiple gestation	n=0 (0.0%)	n=0 (0.0%)
Chronic maternal illness	n=96 (8.1%)	n=26 (7.9)
Maternal infections (including HIV, rubella, syphilis, hepatitis B, cytomegalovirus, toxoplasmosis, tuberculosis and malaria)	n=0 (0.0%)	n=1 (0.3)
Maternal haemoglobin (g/L)	124.0 (10.0)	124.0 (10.0)
Maternal malignancy	n=0 (0.0%)	n=0 (0.0%)
Maternal substance abuse (including alcohol) and smoking	n=0 (0.0%)	n=0 (0.0%)
Maternal use of teratogenic drugs during pregnancy	n=628 (53.2)	n=222 (67.1%)
Maternal prenatal anxiety and depression/mental stress	n=0 (0.0%)	n=0 (0.0%)
Maternal preeclampsia and eclampsia	n=10 (0.9%)	n=4 (1.2%)
Placental structural anomalies	n=0 (0.0%)	n=0 (0.0%)
Foetal growth restriction	n=67 (5.7%)	n=14 (4.2)
Gestational age at delivery, weeks*	39.6 (1.2)	39.3 (1.5)
Birth weight, kg*	3.2 (0.4)	3.2 (0.5)
Birth length, cm*	49.2 (1.8)	49.0 (2.1)
Head circumference at birth, cm*	34.0 (1.2)	34.0 (1.3)
Apgar at five min*	9.5 (0.6)	9.6 (0.7)
Age at hospital discharge, days†	3.0 (2.0 to 4.0)	2.0 (1.0 to 3.0)
Boys*	n=564 (47.8)	n=160 (48.3)
Hyperbilirubinaemia*	n=49 (4.1)	n=18 (5.5)
Respiratory distress syndrome*	n=16 (1.4)	n=7 (2.1)
Transient tachypnoea of the newborn*	n=11 (0.9)	n=12 (3.6)
Exclusive breastfeeding at hospital discharge*	n=1097 (93.0)	n=300 (90.9)

Data are mean (SD) or number (%) unless otherwise specified.

Missing data below 2% for all variables.

*Mean (SD).

†Median (IQR).

INTER-NDA, INTERGROWTH-21st Neurodevelopment Assessment.