Journal of Pregnancy / 2013 / Article / Tab 3

Research Article

Effects of Maternal Factors on Birth Weight in Japan

Table 3

Differences of birth weight between 2006 and 2010 before and after adjusting each confounding factor by ANCOVA.

ValueDifference
20062010
Difference of birth weight before adjustment by ANCOVA

Birth weight (g)2950.8402937.52013.32013.320

Estimation for net effect on birth weight of each factor by ANCOVA
Partial confounding factors Net effect (g) Total effect (g)

Gestational age at delivery (weeks)39.08738.9850.102160.08116.36011.156
Primiparity 0.5300.544−0.014−104.7961.496
Cesarean delivery 0.2360.285−0.050−2.0460.102
Weight gain during pregnancy (kg)9.8469.8420.00416.2690.064
Female gender 0.4890.4870.002−107.150−0.236
Induction of labor 0.2360.269−0.0339.714−0.322
Pregestational BMI21.05721.092−0.03522.250−0.774
IVF-ET 0.0230.044−0.02137.404−0.785
Smoking habit 0.0530.0440.009−107.593−0.954
Maternal height (cm)158.338158.471−0.13310.270−1.366
Maternal age (year)31.11932.002−0.8832.752−2.428

Difference of birth weight after adjustment by ANCOVA
Birth weight (g)2.164

meant a partial regression coefficient. Net effect was calculated by product of difference and partial regression coefficient. Total effect was derived from sum of net effect.
ANCOVA: analysis of covariance, BMI: body mass index, and IVF-ET: in vitro fertilization and endometrial transfer.

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