[CG] Thromboprophylaxis during pregnancy and the puerperium, a guide to risk assessment & management


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The aim of this guideline is to provide information on risk assessment and management in the prevention of venous thromboembolism (VTE) during pregnancy and the puerperium.

Staff should also be aware of the additional GG+C guideline - Thromboembolic Disease in Pregnancy & Puerperium – Acute Management

Please report any inaccuracies or issues with this guideline using our online form

Introduction and Background

Risk Assessment

Risk assessment for thromboprophylaxis is ongoing throughout pregnancy and should take place routinely during key phases in the woman’s maternity care journey.

  • At Booking
  • At 28 weeks
  • During any antenatal in-patient admission
  • Post-birth in the labour ward setting
  • Prior to postnatal discharge
  • During any postnatal readmission

Risk factors for VTE in Pregnancy & the Puerperium

Risk factors for VTE in pregnancy and the puerperium (RCOG GTG 37a, 2015):

Pre- existing









Previous VTE



Antithrombin deficiency

Protein C deficiency

Protein S deficiency

Factor V Leiden

Prothrombin gene mutation


Antiphospholipid antibodies

Persistent lupus anticoagulant and/ or moderate/ high titre anticardiolipin antibodies and/or ß₂ -glycoprotein 1 antibodies.

Medical comorbidities e.g. cancer; heart failure; active SLE, inflammatory polyarthropathy or inflammatory bowel disease; nephr?oitic syndrome; type 1 diabetes mellitus with nephropathy; sickle cell disease.

Current intravenous drug user

Age > 35 years

Obesity (BMI > 30kg/m² ) either pre pregnancy or in early pregnancy


Gross varicose veins (symptomatic or above knee with assoc phlebitis, oedema/ skin changes)


Obstetric risk factors

Multiple pregnancy

Current pre-eclampsia

Caesarean section

Prolonged labour (> 24hrs)

Mid-cavity or rotational operative delivery


Preterm birth

Post partum haemorrhage (>1 litre/ requiring blood transfusion)

New onset/ transient

These risk factors are potentially reversible and may develop at later stages in gestation than the initial risk assessment or may resolve and therefore what is important is an ongoing individual risk assessment

Any procedure in pregnancy or puerperium except immediate repair of the perineum, e.g. appendicectomy, post partum sterilization

Bone fracture


Ovarianhyperstimulation syndrome

(first trimester only)

Assisted reproductive technology

(ART), in vitro fertilization (IVF)

Admission or immobility  (≥ 3 days bed rest)

e.g. pelvic girdle pain restricting mobility

Current systemic infection

(requiring intravenous antibiotics or admission to hospital)

e.g. pneumonia, pyelonephritis, post partum wound infection

Long distance travel (>4hrs)


Assessment Tools

Following comprehensive history-taking the Midwife/Doctor will complete and document their risk assessment findings within the woman’s Maternity Summary Record and SWHMR as applicable. Supporting tools include:

  • GG+C Antenatal/Postnatal Obstetric risk assessment and management Guide– (Poster)
  • GG+C Antenatal and Postnatal Obstetric risk assessment and management forms– (appendix 1 + 2)
  • The Thrombosis risk assessment box within the antenatal portion of the SWHMR
  • The In-patient Medicine Prescription Form (drug kardex)

Management Plan

If the woman is identified as requiring thromboprophylaxis it is essential that a management plan is made by the Doctor and documented within the hospital based maternal Summary Record with a summary detailed in the maternal hand held record. Antenatal thromboprophylaxis should begin as early in pregnancy as achievable.

  • Any clinician who is uncertain about the need for thromboprophylaxis or the ongoing management plan of patients must seek assistance from a colleague with an interest in medical disorders in pregnancy.
  • Drug contraindications must be considered.
  • Midwives can assess for and administer thromboprophylaxis. Prescribing thromboprophylaxis is an obstetric/medical remit.
  • The thromboprophylaxis reassessment box within the Medicine Prescription Form should be completed at least every 48 hours.
  • Women receiving antenatal thromboprophylaxis should be advised that if they experience any vaginal bleeding or once labour begins they should not inject any further LMWH until reviewed by an obstetrician and an ongoing plan of care documented.
  • Breast-feeding is not contraindicated during post-natal thromboprophylaxis management

Thromboprophylaxis during labour and delivery, including the use of regional anaesthesia and analgesia

Thromboprophylaxis during labour and delivery

  • Women receiving prophylactic or therapeutic doses of LMWH during the antenatal period should be reviewed by a Senior Obstetrician before term (37+0 weeks) and a plan for labour/birth documented.
  • It is important to discuss the implications of treatment with LMWH for regional anaesthesia and analgesia with the women before labour or caesarean section – the obstetrician (and/or obstetric anaesthetist) should inform all women taking LMWH about regional anaesthesia and labour. All women should be given the patient information leaflet – ‘Information for pain relief during labour or delivery for pregnant patients on blood thinning medications’ (Appendix 2)


Regional anaesthesia or analgesia

  • This may only be considered following discussion with a senior anaesthetist
  • An individual management plan should be documented in the patient’s notes


To minimise or avoid the risk of epidural haematoma

  • Regional techniques should not be used until at least 12 hours after the previous prophylactic dose of LMWH
  • When a woman presents while on a therapeutic regimen of LWMH regional techniques should not be employed for at least 24 hours after the last dose of LMWH.
  • LMWH should not be given for 4 hours after use of spinal anaesthesia or after the epidural catheter has been removed; the cannula should not be removed within 12 hours of the most recent injection.

Postnatal Risk Assessment

To be completed for every woman by the Midwife/Doctor:

  • immediately following delivery prior to transfer to P/N ward
  • on postnatal readmission

Completed postnatal risk assessment form should be filed in the Maternity summary record and a brief summary written in the maternal post-natal record.

Prescription if required should be written in the patient’s Medicine Prescribing Form (drug kardex) prior to transfer to the ward.

Thromboprophylaxis – ongoing management

Early mobilisation and avoidance of dehydration is recommended for all postnatal women

For women at high risk of postpartum VTE the recommended duration of thromboprophylaxis is 6 weeks.

For women with intermediate risk the recommended duration of thromboprophylaxis is 10 days.

LMWH dosage is graduated based on the woman’s most recent weight. 

Use of Anti-Embolic Stockings (AES)

The evidence supporting the use of graduated elastic compression stockings is varied. Pregnant women considered to be at an increased risk of VTE and have a contraindication to LMWH, should be advised to wear AES when immobilised/hospitalised during the antenatal period. (RCOG 2015, SIGN 2010)

Accurate fitting and careful instruction in the correct application of the hosiery is essential to avoid discomfort and assist rather than prevent venous return.

For women who are risk of VTE postnatally and have a contraindication to LMWH, AES should be considered. Compliance  factors  should  be  evaluated  and  the  option  of  below  the  knee stockings explored.

Post-natal – self administration LMWH

Women who require continuing with sub-cutaneous thromboprophylaxis injection on discharge from the ward setting should be encouraged and supported to self-administer in the community setting.

The woman will be shown the correct method by the ward midwife and have the opportunity to self-administer under supervision. 

Appendix 1: Antenatal Assessment and Management Flowchart

Appendix 2: Postnatal Assessment and Management Flowchart

Appendix 3: Patient Assessment and Consent for self administration of Sub-Cutaneous Enoxaparin (Clexane) in Hospital and in the Home Setting

Appendix 4: Guidance on how to take your enoxaparin injections at home (patient leaflet)

Last reviewed: 06 September 2017

Next review: 01 December 2021

Author(s): Andrew Thomson, Catherine Bagot

Approved By: Dr Catrina Bain on behalf of Obstetric Governance Group

Document Id: 580