Causes of first trimester miscarriage

Genetic

• 3-5% of couples presenting with recurrent miscarriage carry a chromosomal anomaly, most commonly a balanced translocation.

• Incidence of balanced translocation in general population ~0.4%.

• Female is twice as likely as male to be carrier of translocation.
Endocrine factors

• Well controlled diabetes mellitus and thyroid disease are not associated with recurrent miscarriage. 
Incidence of sub-clinical diabetes mellitus is not higher in recurrent miscarriage.
• Poorly controlled diabetes mellitus is associated with increased risk of miscarriage

• Ultrasound features of polycystic ovaries are more prevalent in women with recurrent miscarriage (50%) compared to general population (22%). 

Pre-pregnancy suppression of LH in women with LH hypersecretion does not improve outcome.