Table 2.
Quantitative levels of trace elements grouped by intertwin birthweight discordance.
| Element/Units | Total (n = 60) | IBWD≥20% (n = 21) | IBWD<20% (n = 39) | t/Z | p | ||
|---|---|---|---|---|---|---|---|
| % of detection | Mean ± SD | Median (IQR) | Median (IQR) | Median (IQR) | |||
| M_Tl/ng/L | 84.62 | 107.197 ± 244.239 | 26.085 (20.528) | 42.214 (750.965) | 21.440 (13.737) | 3.054 | 0.002 |
| UL_Sr/μg/L | 100 | 19.519 ± 6.230 | 20.244 (5.837) | 16.768 (10.786) | 21.141 (5.874) | 2.599 | 0.013 |
| UL_Tl//ng/L | 47.73 | 85.511 ± 226.776 | 14.372 (8.758) | 23.804 (759.842) | 13.455 (6.451) | 3.150 | 0.002 |
| US_Cr/μg/L | 100 | 0.686 ± 0.660 | 0.491 (0.366) | 0.393 (0.185) | 0.578 (0.336) | −2.393 | 0.017 |
| US_Sr/μg/L | 100 | 19.622 ± 6.323 | 20.134 (7.332) | 16.532 (12.687) | 21.384 (6.990) | 2.157 | 0.048 |
| PL_I/μg/kg | 100 | 115.897 ± 216.627 | 54.227 (93.957) | 80.449 (72.726) | 35.491 (74.444) | 2.474 | 0.013 |
| PL_Sr/μg/kg | 100 | 203.153 ± 322.026 | 92.569 (127.169) | 72.681 (57.112) | 108.566 (125.259) | −2.602 | 0.009 |
| PL_V/μg/kg | 93.22 | 0.591 ± 0.635 | 0.341 (0.715) | 0.846 (1.256) | 0.290 (0.430) | 2.618 | 0.009 |
| PS_Mo/μg/kg | 100 | 11.603 ± 5.119 | 10.652 (6.019) | 8.783 (4.932) | 11.036 (7.254) | −3.198 | 0.001 |
| PS_Pb/μg/kg | 100 | 12.937 ± 8.437 | 10.611 (8.022) | 8.093 (4.153) | 12.162 (9.104) | −2.319 | 0.020 |
| PD_Mo/μg/kg | 100 | 1.044 ± 8.260 | 0.317 (5.771) | 1.149 (7.016) | −0.440 (6.512) | 2.485 | 0.013 |
IBWD, intertwin birthweight discordance; M, maternal blood; UL, umbilical cord blood of larger twin; US, umbilical cord blood of smaller twin; PL, placenta of larger twin; PS, placenta of smaller twin; PD, differences of trace elements in placenta of twins (PL-PS); Tl, thallium; Sr, strontium; Cr, chromium; V, vanadium; I, iodine; Mo, molybdenum; Pb, lead.