Changes in the main dimensions of the pelvis over time in first- and second-time mothers of different heights

Objective. To conduct a comparative analysis of changes in the dimensions of the great pelvis in primiparous and multiparous women of different heights at registration for pregnancy and on the eve of childbirth.
Materials and methods. The study included 260 women with a singleton pregnancy. Depending on their height, all the patients were divided into two groups: A and B. Group A (N = 108) included women whose height was below 167 cm. Group B (N = 152) included patients whose height was 167 cm or more. Groups A and B were divided into subgroups (A1 and A2, B1 and B2) depending on the parity of the birth: subgroups A1 (n = 57) and B1 (n = 68) – first-time mothers; subgroups A2 (n = 51) and B2 (n = 84) – second-time mothers.
Results. Changes in the size of the large pelvis during pregnancy are a physiological process, and their severity depends on the woman's constitutional characteristics, particularly her height. The most statistically significant changes were observed in the conjugata externa of low-height first-time mothers and high-height second-time mothers, while the other dimensions of the pelvis did not show any statistically significant changes.
Conclusion. Thus, it is not possible to judge the width and size of the pelvis solely based on height. It is always necessary to measure the pelvis both during pregnancy registration and on the eve of childbirth, as this will help to establish the dynamic transformation of the pelvis during gestation and may contribute to improving the assessment of the risk of obstetric complications.

1. Pavličev M., Romero R., Mitteroecker P.Evolution of the human pelvis and obstructed labor: new explanations of an old obstetrical dilemma. Am J Obstet Gynecol. 2020; 222(1): 3–16. doi: 10.1016/j.ajog.2019.06.043.

2. Washburn S. L. Tools and human evolution. Sci Am. 1960; 203: 63–75.

3. Belov E.V., Patlataya N.N., Bolotskih V.A., et al. Anthropometric indicators of body proportionality of girls and boys living in the Moscow region. Zhurnal anatomii i gistopatologii. 2023; 12(4): 98–102. doi: 10.18499/2225-7357-2023-12-4-98-102. (in Russian)

4. Vyshedkevich E.D., Sheriev S.R., Paleeva I.S., et al. Results of magnetic resonance pelviofetometry in pregnancy with a large fetus. Mezhdunarodnyj nauchno-issledovatel'skij zhurnal. 2024; 3. doi: 10.23670/IRJ.2024.141.36. (in Russian)

5. Ponomarev A.S., Manakova D.V. The relationship between pelvimetry indicators and anthropometric characteristics in female students of the Ural State Medical University. Vestnik UGMU. 2025; 10(1): 25–33. doi: 10.52420/usmumb.10.1.e00134. (in Russian)

6. Medvedeva N.N., Pribushenya O.V. Physical and anamnestic characteristics of pregnant women depending on height. In: Vasil'ev S.A., Ulezko E.A., eds. Sovremennye perinatal'nye medicinskie tekhnologii v reshenii problem demograficheskoj bezopasnosti. Minsk. 2024; 17: 468–474. doi: 10.63030/2307-4795/2024.17.G.12. (in Russian)