The aim of the study was to determine the placenta volume (PV) at 11-13⁺⁶ weeks of gestation by three-dimensional ultrasound (3DUS) in combination with birth weight, placenta weight, placenta volume at birth and maternal age, body mass index (BMI) additionally.

From June 2011 to July 2012, placental volumes were prospectively measured by VOCAL (Virtual Organ Computer-aided Analysis) method in 129 normal pregnancies of Peking Union Medical College Hospital at 11-13⁺⁶ weeks of Gestation, multiples of the median was calculated (MOM) after logarithmic₁₀ transformation referring to different crown-rump length (CRL) groups. The normal pregnancies were selected without any combinations or fetal abnormalities, then recorded the birth weights, placenta diameters and thicknesses and placenta weight at delivery. The maternal basic status was also concluded in the study.

Correlation analysis results: (1) The transformed placenta volume MOM showed a significant correlation (Spearman rho=0.200, P<0.05) with birthweight but not with placenta weight or placenta volume calculated as ellipsoid (Spearman rho=0.164, 0.112 respectively, P>0.05). (2) The birthweight showed significant correlations with placenta weight, placecnta volume and maternal BMI (Spearman rho=0.478, 0.361, 0.259 respectively, P<0.01). (3) The placenta weight at birth showed a significant correlation with placenta volume at birth (Spearman rho=0.467, P<0.01) and maternal BMI (Spearman rho=0.198, P<0.05). Regression analysis results: (1) Birth weight (g)=1136.9+1530.9×MOM+45.3×BMI-15.0×maternal age (r?=?0.29, P?=?0.01<0.05). (2) Placenta weight (g)=88.1+315.3×MOM+10.0×BMI+0.1×maternal age (r?=?0.27, P?=?0.02<0.05).

The placental volume at 11-13⁺⁶ weeks of gestation has significant correlation with birthweight. This might assist in the identification of the high risk pregnancies caring large or low for gestational age fetuses.