Generic Name: LMW Heparins
Indications: Blood Thinner
FDA Drug Category: B

Summary Recommendations: LMW blood thinners like Heparin are prescribed for the treatment of blood clotting disorders in women with a history of blood clots and to prevent other pregnancy complications. LMW heparins do not cross the placenta and are considered a safe alternative to traditional heparin during pregnancy.

Names for common LMW heparins include enoxaparin, Fragmin and dalteparin.

General Precautions: LMW heparins are the heparins of choice during pregnancy. If you find out you’re pregnant while taking heparin, your doctor may switch you to a LMW heparin. Never stop taking a blood thinner without the express direction of your doctor. Fatal side effects can occur in some patients with clotting disorders if medication use is stopped.

Effect While Trying to Conceive: LMW heparins have no negative side effects on fertility, either male or female. In some cases, heparin is prescribed to increase the chances of conception during IVF treatment. Clinical studies on the effect of LMW heparins during IVF treatment have revealed an increase in live births of up to 20%.

Effects on Pregnancy: LMW heparins do not appear to have any impact on the fetus because they do not cross the placenta. In a review of all clinical studies pertaining to the use of LMW heparins during pregnancy, researchers found no evidence of increased pregnancy complications or birth defects in the group using the drugs. The total rate of complications hovered at 3%, which is comparable to the normal rate of complications in women no receiving treatment.
LMW heparins do not cross into the placenta due to the positive polarity.

Safe During Breastfeeding: LMW heparins are safe for use while breastfeeding. Many mothers who take the blood thinner during pregnancy continue treatment after birth to prevent blood clots from forming. A small amount of the LMW heparin will pass into milk, but the body typically digests the medication, so there are no adverse side effects. LMW heparins are injected – not taken orally – for this reason.