Table 2.

Factors associated with the placenta-to-birth weight ratio, placental weight and birth weight

Factors	Placenta-to-birth weight ratio (g/kg) β (95% CI)^b	Placental weight (g) β (95% CI) ^b	Birth weight (g) β (95% CI) ^b
Maternal age, years	−0.48 (−0.75, −0.21)^*	−8.52 (−9.65, −7.39)^**	−35.68 (−39.51, −31.85)^**
Maternal education	−0.39 (−1.74, 0.96)	6.03 (0.43, 11.64)^*	41.94 (22.95, 60.93)^**
Parity	1.36 (0.18, 2.55)^*	26.39 (21.48, 31.31)^**	119.19 (102.51, 135.87)^**
Any prenatal cigarette smoking (yes, no)	6.77 (4.83, 8.71)^**	−15.37 (−23.43, −7.31)^**	−205.49 (−232.91, −178.08)^**
Any prenatal alcohol consumption (yes, no)	−2.07 (−4.01, −0.12)^*	−4.09 (−12.14, 3.96)	14.32 (−12.99, 41.63)
Pre-pregnancy BMI, kg/m²	0.71 (0.50, 0.91)^**	7.14 (6.30, 7.97)^**	25.03 (22.20, 27.85)^**
Total pregnancy weight change, kg	−0.07 (−0.21, 0.08)	3.70 (3.09, 4.31)^**	21.04 (18.95, 23.13)^**
Gender of infant, female	1.75 (−0.42, 3.92)	−58.63 (−67.63, −49.62)^**	−339.97 (−370.55, −309.39)^**
Gestational age, weeks	−3.34 (−4.10, −2.58)^**	23.47 (20.31, 26.63)^**	181.46 (170.73, 192.18)^**

β-coefficient and 95% confidence interval for linear regression model adjusted for components of perinatal score except for birth weight (maternal age, neonatal gender, season of birth, duration of second stage labor and intention to breast feed), maternal education, infant parity, maternal pre-pregnancy BMI, total pregnancy weight change, any prenatal cigarette smoking, any prenatal alcohol consumption, and gestational age.

P<0.05,

^**

P<0.001