The loss of a pregnancy at less than 24 weeks’ gestation

Aetiology

Risk factors

• Maternal age >30-35 (largely due to an increase in chromosomal abnormalities)
• Previous miscarriage
• Obesity
• Chromosomal abnormalities (maternal or paternal)
• Smoking, cocaine, alcohol misuse
• Uterine anomalies
• Previous uterine surgery
• Anti-phospholipid syndrome
• Coagulopathies
• Infections - CMV, rubella, toxoplasmosis, listeria
• Severe emotional upsets, stress
• Iatrogenic loss e.g. after. CVS
• Uncontrolled diabetes

Pathophysiology

• Early miscarriages occur in the first trimester (<12-13 weeks) and are more common than late miscarriages, which occur at 13-24 weeks

Types of miscarriage

• Threatened miscarriage: this is where there are some mild symptoms of bleeding with the foetus retained within the uterus as the cervical os is closed
  • Hence there is the 'threat' of a miscarriage, but it is not certain
  • There may be little or no pain
  • Ultrasound reveals that the foetus is present intrauterine