Transient osteoporosis of the hip in pregnancy - a case series.

Objective: Transient Osteoporosis of the Hip is a self-limiting disorder of severe hip joint pain presenting in pregnancy or postpartum, of which magnetic resonance imaging (MRI) is the modality of choice for diagnosis. Clinical data regarding transient osteoporosis of the hip is limited, precluding evidence-based decision-making such as recommended mode of delivery. In this case-series retrospective study, we aim to describe the natural course of transient osteoporosis of the hip during pregnancy and the postpartum period including implications of the mode of delivery.

Methods: All women diagnosed with unilateral/bilateral transient osteoporosis of the hip by MRI during pregnancy or postpartum between 2010 and 2019 at a single tertiary medical center were retrospectively studied. All MRI scans were reviewed by an experienced radiologist at the same single tertiary medical center. Data obtained from patients' electronic medical records and telephone questionnaires included maternal baseline characteristics, obstetric history, and current pregnancy obstetric and clinical outcome characteristics. Outcomes of normal vaginal delivery (NVD) and cesarean delivery (CD) were compared and analyzed.

Results: Thirty-four women were diagnosed with unilateral or bilateral transient osteoporosis of the hip during pregnancy (17 women) and postpartum (17 women). The mean maternal age was 34.18 ± 4.75 years. A family history of osteoporosis was reported in a rate of 29.4%. The rate of smokers was 47.1%, 32.4% of pregnancies were conceived by in-vitro fertilization (IVF), pre-pregnancy and term body mass index (BMI) were 22.03 and 27.6, respectively. No significant differences were found between NVD and CD in all parameters evaluated. Of 15 women with a sequential pregnancy, two were diagnosed with transient osteoporosis of the hip (13.3%).

Conclusion: Women diagnosed with transient osteoporosis of the hip had advanced maternal age, low BMI, family history of osteoporosis, prevalent smoking and IVF pregnancies. Transient osteoporosis of the hip was bilateral in 25% and presented postpartum in 50% of cases. There was no significant difference in maternal outcomes between NVD and CD. Higher awareness of this potential diagnosis during pregnancy and postpartum may improve patient management and outcomes.