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LOW MOLECULAR WEIGHT HEPARINS (LMWH)

Bloodthinning injections used in some fertility treatments to reduce clotting risks and support healthy implantation and pregnancy.

Why LMWH may be used in fertility care

Low molecular weight heparins (LMWH) — including Clexane, Inhixa, and Fragmin — are blood thinning medicines used to reduce the risk of blood clots. In fertility care, they may be prescribed for patients with inherited clotting disorders (like factor V Leiden or protein C/S abnormalities) or those who have experienced recurrent implantation failure. 

They are thought to improve blood flow to the embryo and placenta, supporting implantation and pregnancy. 

Your exact prescription will be tailored to you, and you’ll find your personalised schedule and instructions in the Care Fertility treatment companion app, Salve. If you’re unsure or worried about how you’re feeling, our team is only a call or message away. 

Clexane

Active ingredient: Enoxaparin 
Available form: Solution for injection in prefilled syringes 

Clexane is a low molecular weight heparin (LMWH) that thins the blood to help prevent clots. It may be prescribed to reduce the risk of blood clots and support implantation or pregnancy in certain patients. 

How to store it

Keep below 25°C in its original packaging, away from heat and sunlight.
How to take it

Inject under the skin at the times and dosage shown in your treatment companion app, Salve.  

 
Possible side effects
  • Common: Easy bruising, small pink patches at injection site, skin rash or itching, bruising or pain at the injection site, headaches, low red blood cell count, high platelet counts. 
  • Uncommon: Mild bleeding or nosebleeds. 
  • Rare: Allergic reactions – swelling of the face, lips, tongue, or difficulty breathing (seek urgent medical help). 

Contact your Care Fertility team if you notice nosebleeds, blood in your urine or stool, unusual bruising, or bleeding lasting longer than 15 minutes. 
Disposal Place used syringes in the provided sharps bin. When full, seal, sign, and return it to your clinic. 

Inhixa

Active ingredient: Enoxaparin 
Available form: Solution for injection in prefilled syringes

Inhixa is an LMWH that reduces blood clotting. It can lower the risk of blood clots and may help support successful implantation and pregnancy.

How to store it

Keep below 25°C in its original packaging.
How to take it

Inject under the skin at the times and dosage shown in your treatment companion app, Salve. 

 
Possible side effects
  • Common: Bruising at injection sites, pink skin patches, rash or hives, itching, headaches, low red blood cell count, high platelet counts. 
  • Uncommon: Nosebleeds, mild gastrointestinal bleeding. 
  • Rare: Allergic reactions (seek urgent medical help). 

Contact your Care Fertility team if you notice prolonged bleeding, blood in urine or stool, or unexplained bruising. 
Disposal

Place used syringes in the provided sharps bin. When full, seal, sign, and return it to your clinic. 

Fragmin

Active ingredient: Dalteparin sodium 
Available form: Solution for injection in prefilled syringes 

Fragmin is an LMWH used to thin the blood and prevent clot formation. It may be used for patients with clotting disorders or recurrent implantation failure to improve pregnancy outcomes. 

How to store it

Keep below 25°C in its original packaging.
How to take it

Inject under the skin at the times and dosage shown in your treatment companion app, Salve. 
Possible side effects
  • Common: Bruising or pain at injection sites, rash or hives, itching, pink skin patches, headaches, low red blood cell count, high platelet counts. 
  • Uncommon: Nosebleeds, mild bleeding in stools or urine. 
  • Rare: Allergic reactions (seek urgent medical help). 

Contact your Care Fertility team if you experience prolonged bleeding, unusual bruising, or blood in urine or stool. 

 

Important information: 

  • LMWH is not specifically licensed for fertility treatment, but it is considered safe when monitored by your Care Fertility team. 
  • Do not use if you’ve had major trauma, haemophilia or other bleeding disorders, stomach ulcers, recent brain bleeds, eye or nervous system surgery, or low platelet counts. 
  • Avoid epidurals or spinal anaesthesia while using LMWH. 
  • Use with caution if you have severe, uncontrolled high blood pressure. 
  • LMWH does not cross the placenta and is not known to harm pregnancy. 
Disposal

Place used syringes in the provided sharps bin. When full, seal, sign, and return it to your clinic. 

When to call Care Fertility

Contact your Care Fertility team immediately if you experience: 

  • Unusual or prolonged bleeding 
  • Blood in your urine or stools 
  • Severe or worsening headaches 
  • Rapid swelling or unexplained bruising 
  • Signs of an allergic reaction: swelling of the face, lips, tongue, or throat, or difficulty breathing 

You can contact us via the Care Fertility companion app, Salve, or call your clinic directly. If you can’t reach us and need urgent medical help, call NHS 111 or attend your nearest A&E.