Body weight and crown-heel length autopsy standards in a Macedonian perinatal population: single centre experience

Abstract

Background & objectives: Foetal reference values are available for several European countries, but no reference values exist for the North Macedonian population. We aimed to establish accurate body weight and crown-heel length standards, indigenous to our country. Methods: We reviewed 4,073 consecutive foetal/perinatal autopsies performed between 2012 and 2019. Excluded were cases with: multiple pregnancies, unknown gestational age, congenital abnormalities, intrauterine growth restriction, hydrops, severe septicaemia/virosis, fixed/ frozen specimens, newborns aged >24 hours, severe haemorrhage, and alloimmunization. BW was measured in grams and CHL in centimetres at the day of admission. Percentile curves were calculated with the Altman method. Results: 1,129 cases met the inclusion criteria (age range: 11-42 gw, 64.07% males, 35.93% females, 1.15% undetermined sex), of which 456 (40.39%) were miscarriages, 326 (28.86%) stillborn foetuses, 243 (21.52%) neonates and 15 (1.33%) foetuses were medically terminated pregnancies. BW in grams (BWg) had the following relationship with gw: BWg = 302.923 + gw * -68.766 + gw2 *3.481 (R2 = 0.930, p <0.0001). The relationship between CHL in cm (CHLcm) and gw was calculated as following: CHLcm = -23.89 + gw * 2.926 + gw2 * - 0.0268 (R2 = 0.926, p < 0.0001). Corresponding standard deviations were modelled to derive lower and upper reference limits. Conclusion: The current autopsy study provides bodyweight and crown-heel reference standards with standard deviations, at each gestational age, which are representative of our mixed population. The easy-to-use percentile charts could serve as a valuable tool for the practicing pathologist when performing perinatal autopsies. We believe that strict adherence to the eligibility criteria, the consistency of the autopsy procedure, and the well-designed statistical approach, support the reliability of our results.