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

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.

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

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.

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)**.

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.