Recurrent Miscarriages


This guideline applies to adults aged 18 and over


Recurrent miscarriage is defined as the loss of 3 consecutive, intrauterine pregnancies or 1 second-trimester miscarriage.

  • Clinical pregnancies are confirmed either by a positive serum human chorionic gonadotrophin (hCG) or an ultrasound scan.
  • In cases where a serum HCG or ultrasound scan has not been performed, then a clinical pregnancy is at least 5 to 6 weeks gestation by last menstrual period (LMP).
  • This definition does not include biochemical pregnancies which are very common and do not usually indicate underlying pathology.


Recurrent miscarriage remains unexplained in 50 to 75% of cases. Increasing maternal age is the most important risk factor for recurrent miscarriage.





Consider investigating recurrent pregnancy loss after:              

  • 3 or more first-trimester miscarriages.
  • 1 second-trimester miscarriage.



  • Menstrual cycles
  • Lifestyle factors, especially illicit drugs, smoking, alcohol, and obesity
  • History of deep vein thrombosis (DVT) or pulmonary embolism (PE) which may suggest antiphospholipid syndrome
  • Previous successful pregnancies
  • Previous miscarriages, termination of pregnancies (TOPs), and ectopic pregnancies
  • All previous investigations, especially abnormal results
  • Any previous treatments to cervix.


Risk factors for recurrent pregnancy loss

  • Advanced maternal age
  • Maternal obesity or being significantly underweight
  • Smoking (either parent)
  • Alcohol (either parent)
  • Genetic – translocation, e.g. parental chromosomal rearrangements, embryonic chromosomal abnormalities
  • Anatomical – congenital uterine abnormalities, e.g. uterine septum, cervical weakness
  • Endocrine – polycystic ovary syndrome (PCOS), poorly controlled diabetes, thyroid dysfunction, hyperprolactinaemia, e.g. oligomenorrhoea



  • BMI
  • Consider performing abdominal examination and speculum examination to check for obvious uterine or cervical abnormalities, e.g. double cervix.
  • Ensure cervical screening is up to date.





Pelvic USS (non pregnant)

Day 2-5 FSH




Information to include when referring: 

  • Details of full obstetric history (include miscarriages/ TOPs/ ectopic pregnancies)
  • Whether any previous treatment to cervix (if so please include date of last smear & result)
  • Relevant past medical / surgical history
  • Current regular medication

Investigations prior to referral

• Pelvic USS (non pregnant)


Advice and Guidance

No formal advice and guidance service available.

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Clinical editor

Dr Melanie Schick, GP


Miss Lisa Verity, Consultant Gynaecologist, RCHT