Table 1: Characteristics of the newborn infants and their mothers.

       Newborn weighta(kg) 3.20 (2.95, 3.50)
       Newborn lengtha(cm) 50.00 (48.00, 51.00)
       Newborn head circumferencea(cm) 35.00 (34.00, 35.50)
       Gestational weight gaina (kg) 10.52 (8.01, 13.50)
       Ageb (year, n= 759)
             < 18
             18- 34.9
             ≥ 35

20 (2.60)
640 (84.40)
99 (13.00)
       Educationb (n= 759)
             low
             moderate
             high

185 (24.40)
486 (64.00)
88 (11.60)
       Economic statusb (n= 754)
             low
             moderate
             high

271 (35.90)
374 (49.60)
109 (14.50)
       Gestational ageb (n= 759)
             preterm
             early term
             full term
             late term

16 (2.11)
424 (55.90)
302 (39.81)
17 (2.20)
     Birth orderb (n= 758)
             first birth
             second birth
             ≥ third birth

326 (43.00)
316 (41.70)
116 (15.30)
      Medical problem (n= 585)
             Yes
             No

30 (5.11)
555 (94.90)

a median (percentile 25, 75), b expressed as frequency (percent).