Table 3.
Allometric growth relationships between different placental compartments and fetal mass, Mf, during gestation. Values represent allometric exponents (B) and constants (A) calculated using the linear regression equation log Y = B · log Mf + log A where Y refers to the compartment variable and logA is the intercept on the log Y axis
| Compartment | Exponent B (SEM) | Constant A | P-value (B is not 1) |
|---|---|---|---|
| Volume placenta | 0.544 (0.0176) | 5.3358 | *** |
| Volume IVS | 0.518 (0.0226) | 3.0012 | *** |
| Volume Villi | 0.552 (0.0221) | 2.4912 | *** |
| Volume Tro | 0.593 (0.0238) | 0.4728 | *** |
| Volume Str | 0.496 (0.0232) | 1.7398 | *** |
| Volume FC | 0.862 (0.0315) | 0.0430 | *** |
| Surface Villi | 0.735 (0.0239) | 0.0266 | *** |
| Surface FC | 0.909 (0.0297) | 0.0066 | ** |
| Length Villi | 0.861 (0.0283) | 0.0770 | *** |
| Length FC | 0.912 (0.0320) | 0.1790 | ** |
| Number All | 0.584 (0.0199) | 1.1874 | *** |
| Number Tro | 0.601 (0.0201) | 0.4144 | *** |
| Number Str | 0.559 (0.0223) | 0.6569 | *** |
| Number FCE | 0.619 (0.0263) | 0.1255 | *** |
| Arith thickness VM | −0.203 (0.0133) | 26.45 | *** |
| Arith thickness Tro | −0.195 (0.0121) | 13.23 | *** |
| Arith thickness Str | −0.214 (0.0188) | 13.38 | *** |
| Harm thickness VM | −0.300 (0.0189) | 44.44 | *** |
| Harm thickness Tro | −0.290 (0.0181) | 22.89 | *** |
| Harm thickness Str | −0.296 (0.0226) | 13.26 | *** |
| Ratio VM | 0.097 (0.0094) | 0.5953 | *** |
| Ratio Tro | 0.095 (0.0096) | 0.5777 | *** |
| Ratio Str | 0.088 (0.0134) | 0.9741 | *** |
IVS, intervillous space; Villi, terminal and intermediate villi; Tro, villous trophoblast; Str, villous stroma; FC, fetal capillaries; FCE, fetal capillary endothelium; Arith, arithmetic mean; Harm, harmonic mean; Ratio, index of thickness variability; VM, villous membrane (trophoblast + stroma).
**
P < 0.01
***
P < 0.001