Table 4 Univariate association among different prenatal and postnatal variables and infant's difficult behaviors at the age of 3 months, 6 months and at both 3 and 6 months: odds ratio (OR) with 95% confidence interval (CI)^†

Demographic characteristics

Maternal age: ≤ 25

64 (34.0)

2.58 (1.15-5.77)*

2.25 (0.95-5.36)

2.64 (0.91-7.59)

   25-30 years

62 (33.0)

1

1

1

   ≥ 31

62 (33.0)

1.72 (0.76-3.91)

1.19 (0.48-2.96)

1.05 (0.32-3.47)

Family structure: Marriage

156 (83.0)

1

1

1

   Cohabitation

25 (13.3)

1.71 (0.71-4.10)

1.20 (0.44-3.27)

1.95 (0.65-5.84)

   Single

7 (3.7

1.81 (0.39-8.52)

2.43 (0.51-11.59)

2.80 (0.50-17.77)

Education: Secondary or lower

55 (27.3)

1.05 (0.53-2.07)

1.30 (0.62-2.74)

1.41 (0.59-3.37)

   Higher (college or university)

133 (70.7)

1

1

1

Infant's gender: Boy

107 (56.6)

1.20 (0.64-2.25)

1.72 (0.84-3.53)

1.43 (0.60-3.41)

   Girl

82 (43.4)

1

1

1

First child

103 (54.8)

1

1

1

Have older children

85 (45.2)

0.90 (0.86-1.70)

1.22 (0.60-2.47)

0.92 (0.39-2.15)

Perinatal biomedical variables

Delivery mode:

   Vaginal delivery

131 (69.7)

1

1

1

   Cesarean section

57 (30.3)

1.72 (0.89-3.33)

1.03 (0.49-2.18)

1.09 (0.44-2.70)

Medications used during vaginal delivery:

   No medications

67(54.9)

1

1

1

   Epidural anesthesia

19 (15.6)

2.13 (0.73-6.19)

1.12 (0.34-3.66)

1.71(0.46-6.33)

   Oxytocin

22 (18.0)

0.48 (0.19-2.18)

0.90(0.28-2.89)

0.64(0.13-3.20)

   Epidural and oxytocin

14 (11.5)

0.81 (0.20-3.27)

0.91 (0.22-3.76)

1.10(0.21-5.75)

Birth weight: Normal

154 (81.5)

1

1

1

   SGA

9 (4.8)

0.71 (0.14-3.55)

1.04(0.21-5.32)

0.88(0.10-7.44)

   LGA

26 (13.8)

1.53 (0.64-3.62)

0.83(0.29-2.36)

1.24(0.39-3.97)

Apgar scores 1 minute after birth: 9-10

43 (75.7)

1

1

1

   8 or lower

46 (24.3)

0.56 (0.26-1.24)

1.78 (0.84-3.80)

1.24(0.48-3.18)

Apgar scores 5 minutes after birth: 9-10

174 (92.1)

1

1

1

   8 or lower

15 (7.9)

0.15 (0.02-1.18)

0.52(0.11-2.43)

0.00(0.00-0.00)

The NASC 2 hours after birth: Good

73 (41.5)

1

1

1

   Bad/not good

103 (58.5)

1.08 (0.56-2.07)

0.74(0.36-1.50)

0.87(0.37-2.04)

The NASC 24 hours after birth: Good

122 (71.3)

1

1

1

   Bad/not good

49 (28.7)

1.26 (0.62-2.56)

1.69 (0.79-3.59)

1.09(0.422.85)

Perinatal psychosocial variables

Pregnancy planed

134 (74.0)

1

1

1

Not planed

47 (26.0)

1.33 (0.70-2.92)

1.51 (0.68-3.33)

2.00 (0.77-5.21)

Maternal reactions toward conception: Positive

149 (78.8)

1

1

1

   Negative/ambivalent

40 (21.2)

1.66 (0.77-3.55)

1.70 (0.77-3.75)

3.66(1.47-9.17)**

Paternal reactions towards conception:

   Positive

159 (84.6)

1

1

1

   Negative/ambivalent

29 (15.4)

2.15 (0.95-4.85)

1.79(0.74-4.33)

4.16(1.61-10.76)**

Couple's relationship before pregnancy: Good

112 (60.2)

1

1

1

   Average or bad

74 (39.8)

2.59(1.35-4.94)**

1.50 (0.74-3.06)

3.06(1.25-7.48)*

Couple's relationship during pregnancy: Good

114 (61.3)

1

1

1

   Average or bad

72 (38.7)

1.87 (0.99-3.53)

1.11(0.55-2.25)

1.89(0.81-4.42)

Prenatal smoking:

   Non-smoking

158 (87.8)

1

1

1

   Non-regular smoking

14 (7.8)

0.99 (0.30-3.34)

0.63 (0.13-2.96)

0.53 (0.07-4.25)

   Regular smoking

8 (4.4)

2.46 (0.59-10.28)

2.20 (0.50-9.81)

2.23 (0.42-11.86)

Prenatal alcohol use: No

105 (58.0)

1

1

1

   Yes

76 (42.0)

1.94 (1.01-3.72)*

1.70 (0.82-3.51)

2.30 (0.95-5.58)

Stressful and traumatic experience during pregnancy:

   No

150 (80.6)

1

1

1

   Yes

36 (19.4)

2.63 (1.23-5.59)*

1.89(0.83-4.32)

1.52(0.55-4.19)

Negative emotional experience during pregnancy: Rare

92 (51.1)

1

1

1

   Often

88 (48.9)

2.41 (1.24-4.67)*

1.46 (0.71-2.99)

1.30(0.55-3.06)

Depressiveness 2-3 days postpartum: Low

162 (85.7)

1

1

1

   High

27 (14.3)

0.95 (0.38-2.33)

0.72 (0.25-2.05)

0.46(0.10-2.09)

Psychosocial variables measured 3 months postpartum

Father of the infant living together: Yes

148 (90.8)

1

1

1

   No

15 (9.2)

2.83 (0.96-8.33)

2.03(0.63-6.49)

2.52(0.72-8.77)

Father helps in childcare:

   Yes

138 (86.8)

1

1

1

   No

21 (13.2)

1.73 (0.68-4.43)

1.57(0.28-8.73)

1.41(0.43-4.62)

Couple's relationships during the 3 months postpartum: Good

101(59.8)

1

1

1

   Average or bad

68 (40.2)

1.97 (0.99-3.93)

1.63 (0.74-3.63)

2.74(0.96-7.79)

Stressful/traumatic experience at 3 month postpartum: No

143 (82.7)

1

1

1

   Yes

30 (17.3)

1.56 (0.69-3.53)

0.52 (0.17-1.62)

0.64(0.18-2.29)

Negative emotional experience during the 3 months postpartum:

   Rare

91 (53.8)

1

1

1

   Often

78 (46.2)

2.28 (1.18-4.40)*

1.04(0.50-2.15)

1.75(0.73-4.20)

Depressiveness 3 months postpartum: Low

164 (86.8)

1

1

1

   High

25 (13.2)

1.98 (0.84-4.70)

1.70(0.67-4.30)

2.33(0.82-6.59)

Breastfeeding: Yes

134 (75.3)

1

1

1

   No

44 (24.7)

1.14 (0.54-2.39)

1.33(0.61-2.95)

2.00(0.80-4.97)

Maternal attitudes towards infant-rearing:

   Child oriented, flexible

122 (79.7)

1

1

1

   Parent oriented, rigid

31 (20.3)

2.38 (1.06-5.36)*

1.84 (0.76-4.48)

3.31 (1.25-8.74)*