Medical conditions associated with recurrent miscarriage-Is BMI the tip of the iceberg?

Background: In contrast to sporadic miscarriage, recurrent miscarriage (RM) is a rare entity which affects 1% of couples attempting conception. It is distressing for couples and healthcare professionals as the aetiology is unclear with limited treatment options. Apart from anti-phospholipid syndrome (APS), the strength of associations between RM and commonly investigated endocrine, autoimmune, thrombophilic and uterine structural abnormalities remains uncertain and variable.

Objectives: To assess the prevalence of commonly investigated medical conditions associated with RM.

Study Design: A 9-year retrospective analysis of a prospectively collected database was conducted for 592 patients seen between 2008 and 2016, in tertiary level RM clinic in South Africa.

Results: In this period, 592 patients were assessed. The mean age was 29.73±5.46 (mean±SD), gravidity 4.6±1.82 and parity 0.98±1.05. The mean number of miscarriages per patient was 3.34±1.63, of which two-thirds (61.3%) were in the first trimester, a third (33%) in the second trimester and intrauterine fetal deaths (IUFDs) constituted 6% of total losses. Of the 50% of patients with no identified associated disorders, 15% were unexplained (investigations complete but no associations found), 10% became pregnant during investigation (investigations incomplete) and 25% were lost to follow-up (investigations incomplete). Nearly forty percent (38%) of patients had an associated endocrine disorder (22% PCOS, 11% IGT, 3% Diabetes Mellitus and 2% Thyroid Dysfunction) and 10% a uterine factor (4% Cervical Incompetence, 2% Fibroids, 2% Synechiae and 2% Anomalies). APS and Thrombophilias constituted 3% and 2% of patients respectively. The BMI (mean±SD) amongst patients with Unexplained RM, PCOS and IGT were 28.85±5.95, 30.86±7.79 and 33.40±6.47 respectively. Patients with IGT had significantly higher mean BMI in comparison to those with Unexplained RM (p<0.0001)*** and PCOS (p<0.001)**.

Conclusion: PCOS, IGT and Type II Diabetes are all likely surrogates for elevated BMI and constitute 70% of those women with RM and identified associated medical disorders. In our population, BMI seems to have a substantial impact on recurrent pregnancy loss and future studies should interrogate its effect on recurrent miscarriage.