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 characteristicsChildren 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, years28.4 (3.8)27.4 (4.3)
Maternal body-mass-index, kg/m223.2 (3.0)23.6 (2.8)
Multiple gestationn=0 (0.0%)n=0 (0.0%)
Chronic maternal illnessn=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 malignancyn=0 (0.0%)n=0 (0.0%)
Maternal substance abuse (including alcohol) and smokingn=0 (0.0%)n=0 (0.0%)
Maternal use of teratogenic drugs during pregnancyn=628 (53.2)n=222 (67.1%)
Maternal prenatal anxiety and depression/mental stressn=0 (0.0%)n=0 (0.0%)
Maternal preeclampsia and eclampsian=10 (0.9%)n=4 (1.2%)
Placental structural anomaliesn=0 (0.0%)n=0 (0.0%)
Foetal growth restrictionn=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.