[Associations between birth weight and placental volume in the first trimester]. / Zusammenhänge zwischen Geburtsgewicht und Plazentavolumen im ersten Trimenon.

INTRODUCTION: Associations between the size of the placenta and birth weight have been described before. This connection has also been found in (sonographically estimated) second trimester placental size. The aim of this study was to find out if there are any differences in first trimester placental volume between various birth weight groups. METHODS: Placental volume was obtained from non-smoking women at the end of the first trimester during a period of eight months. After birth, the newborns were divided into four groups: below the 10th, 10th to 50th 50th to 90th and above the 90th centile. As is known from previous research, placenta size changes in proportion to crown-rump-length. Therefore, the medians of the "placenta quotients" (placental volume/CRL) of each group were compared in order to correct for differences in gestational age. RESULTS: Data from 1476 pregnancies could be evaluated. The overall median of the placenta quotient was 0.98. It was 0.85 in the group below the 10th, 0.92 between 10th and 50th, 1.02 between 50th and 90th and 1.10 above the 90th centile (p < 0.0001, median test). DISCUSSION: The finding of associations between early pregnancy placental size and birth weight at term gives hope for the development of new diagnostic methods for the recognition of placenta-associated problems. Further research is required to estimate the clinical possibilities for the detection of pregnancies at risk of severe growth retardation and other conditions.

Correlation of first trimester placental volume and second trimester uterine artery Doppler flow.

Uterine artery Doppler examination can identify impaired trophoblast invasion in the second trimester of pregnancy. High resistance and an early diastolic 'notch' show insufficient physiological conversion of the spiral arteries. Uterine artery Doppler is routinely performed between 22-24 weeks which is relatively late for treatment. In this study we wanted to find out whether women with increased uterine blood flow resistance at 22 weeks already have reduced placental volumes in the first trimester measured with 3D sonography.A total of 1060 women with singleton pregnancies had three dimensional (3D) volume measurements of their placentae between 11-13 weeks and uterine Doppler scans between 21-22 weeks. Stepwise logistic and linear regression analyses were used to show a correlation between placental volume (PV) and a CRL dependent placental quotient (PQ) with uterine perfusion parameters. Uterine perfusion at 21-22 weeks depends significantly on PV or PQ at 11-13 weeks (P< 0.0001 for both) and smoking behaviour (P=0.006). The occurrence of a notch also depends significantly on PV and PQ (P< 0.0001 for both) and also on gravidity (P< 0.0001) and age (P=0.0007) as well as on smoking behaviour (P=0.0094). PV and PQ did not show any dependency on age, gravidity, BMI or smoking habits. Placentae of women with high resistance uterine perfusion in the second trimester are already remarkably small in the first trimester. Placental volumetry is probably an efficient method for early and simple identification of impaired trophoblast invasion.

Three-dimensional ultrasound measurement of the placental volume in early pregnancy: method and correlation with biochemical placenta parameters.

Placental size has been an interesting topic of research for many years. The main aim of this study was to investigate the feasibility of measuring the placental volume at the end of the first trimester using three-dimensional (3D) ultrasound and to correlate these volumes to known placental functional indices and to factors affecting the placenta. Women with singleton pregnancies at the end of the first trimester were included into this study. The volume data of the placentae were correlated to the crown-rump length (CRL), placenta-associated plasma protein A (PAPP-A), free beta-human chroangiogonadotropin (f-beta-hCG) and other factors that may affect the placental size or function. A total of 1462 pregnancies could be evaluated. Comparison between CRL and placental volume proved a significant correlation (r=0.43, P< 0.001). Due to the observed proportional growth of CRL and placental volume, a quotient (placental volume/CRL) was calculated for each case. There were no differences between placenta/CRL-quotients in relation to gravidity, parity or smoking. Correlations could be established between the placental volume and PAPP-A and f-beta-hCG (PAPP-A: r=0.28, P< 0.001, f-beta-hCG: r=0.10, P< 0.001). The measurement of the placenta in the first trimester can be performed in a high percentage of cases. The placenta/CRL quotient represents a simple method to compare placentae from different gestational days. The correlation between placental volume and maternal serum screening parameters might provide a chance to refine first trimester Down's syndrome serum screening. Future studies will be needed to evaluate the possible clinical use of first trimester placental volume measurements.