This study defines normal growth for the various aortic segments in 128 spontaneously aborted human foetuses aged 15-34 weeks. With the use of anatomical dissection, digital-image analysis (using the Leica Q Win Pro 16 system) and statistical analysis (ANOVA, regression equation), a range of length measurements for the ascending aorta, aortic arch and thoracic aorta was examined. No significant gender differences were found (p > or = 0.05). The length of the ascending aorta ranged from 2.63 +/-

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... 0.42 to 10.80 +/- 1.49 mm, according to the linear function y = -4.678 + 0.4647 x +/- 0.8447. The aortic arch length increased from 3.93 +/- 0.57 to 15.25 +/- 1.98 mm, in accordance with the linear model y = -6.079 + 0.6370 x +/- 1.1133. The length of the thoracic aorta ranged from 12.49 +/- 1.85 to 48.82 +/- 6.31 mm, according to the linear pattern y = -19.654 + 2.0512 x +/- 3.5168. The sum of the lengths of these aortic segments generated the linear function y = -30.410 + 3.153 x +/- 5.4332. The relationships between the lengths of the various aortic segments generated the linear regressions: y = -0.2256 + 0.7276 x +/- 0.3093 (for the ascending aorta vs. the aortic arch), y = 0.0252 + 0.3105 x +/- 0.2189 (for the aortic arch vs. the thoracic aorta), and y = -0.2408 + 0.22709 x +/- 0.2026 (for the ascending aorta vs. the thoracic aorta). The ascending aorta, aortic arch and thoracic aorta also increased proportionally (5:7:22) during gestation.