In the present study, the significant difference in mean BUA values found between multiparous and nulliparous females (p = 0.006, Fig.
1) shows that females with no pregnancies had a better BMD than females with 2–3 pregnancies (multiparous). The majority of females with normal BUA values were within the nulliparous group (n = 36). In addition, no cases of osteoporosis were found in the nulliparous group, which further shows that the BMD of multiparous females is more affected. Therefore, the findings of the current study contradict findings from previous studies showing that multi-parity does not affect BMD [
1,
13,
20,
21]. The results of this study may be explained by the high calcium demand during pregnancy, which could theoretically result in a long-term decrease in bone mass [
16]. Other previous studies that have shown a positive or unchanged effect of parity on BMD [
1,
11,
13,
20‐
22] suggest that the higher estrogen levels in the third trimester of pregnancy cause an increased absorption of calcium [
23]. Some of the earlier studies did not observe any effect of parity on BMD [
1,
21] as these studies included relatively older females with higher parity as compared to the current study. This study investigated the long-term effect of parity on BMD whereas previous studies that reported a positive or unchanged effect of parity on BMD were based on the short-term effect on BMD[
1,
11,
13,
20‐
22]. In addition, in contrast to the current study, previous studies have used other bone sites (femoral neck, spine and hip) than the calcaneus bone to assess BMD [
1,
11,
13,
20‐
22], which may explain the difference in findings. Furthermore, the results of the current study showed that the difference in BMD normality between the nulliparous and multiparous groups found in this study cannot be explained by a difference in BMI between the two groups (binary logistic regression model: p = 0.1). Previous studies have suggested that a higher BMI during pregnancy is protective against a decrease in BMD [
24,
25].