Blood Clotting Disorders are a Common Cause of Miscarriages

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A miscarriage can be devastating. Recurrent miscarriages, when a patient experiences three or more consecutive miscarriages, are life changing. Early miscarriages, a miscarriage that takes place during the first trimester, happen for many, often unexplainable, reasons. Nearly every woman will experience an early miscarriage during her reproductive years, many of which will go unnoticed with the pregnancy loss happening before she even realizes she is pregnant.

While one early miscarriage is not cause to be overly concerned for the future success of a later pregnancy, repeatedly experiencing the loss of a pregnancy is cause for further testing.

According to Sage Journals Online’s report from the University of Texas Southwestern Medical Center study Recurrent Miscarriage Syndrome, 55 percent of patients experiencing recurrent miscarriages have an underlying blood clotting disorder as the cause. The good news is that the report also states that “more than 98 percent will have a normal term delivery with preconception ASPIRIN® and addition of postconception heparin to term.”

What are Blood Clotting Disorders That Cause Miscarriage

Blood clotting disorders known as thrombophilia are the most common disorders associated with early miscarriage and late term fetal death. Thrombophilia is the tendency to develop blood clots, in contrast to hemophilia and Von Willebrand disease, which are associated with the absence or lack of clotting agents causing blood to flow more freely.

Thrombophilia patients tend to over produce blood clots and or under produce the enzymes necessary to dissolve the clots. These clots are usually small and free flowing through the blood stream, but over time, can join together to form larger clots. Most patients with thrombophilia will never know they have a clotting disorder because patients rarely experience any symptoms and the disorders are not painful. The first indication of a clotting disorder is often a large blood clot somewhere in the body like the arm or leg, stroke, heart attack, pulmonary embolism, or recurrent miscarriage.

Blood clotting disorders such as Factor V Leiden, antiphospholipid syndrome, and high API-1, are genetic disorders. The greatest indicator and risk factor for blood clotting disorders is a family history of stroke, deep vein thrombosis, or other events associated with blood clots.

Risk factors exacerbating clotting disorders include pregnancy, smoking, obesity, oral contraceptives, and immobility. A genetic disorder alone, in the absence of other risk factors, does not necessarily mean a patient will experience a large clot or clotting emergency in her lifetime. A genetic clotting disorder simply increases the risk that a clotting emergency will occur.

How Do Blood Clotting Disorders Affect Pregnancy and Cause Miscarriage or Pregnancy Loss

Blood clotting disorders, specifically those disorders known as thrombophilia, can lead to early miscarriage, late-term pregnancy loss, or stillbirth. Thrombophilia is characterized as an increased amount of clotting agents in the blood stream.

This increase is accomplished through an overproduction of clotting agents, an underproduction of clot dissolving agents, or both. During pregnancy blood volume increases by as much as 50 percent, and expectant mothers, even those without a genetic clotting disorder, are more likely to develop blood clots because of the increase in certain hormones in the body.

Blood clots flowing through the mother’s blood stream may easily pass through her veins and arteries causing no problems, but the veins of the placenta are much smaller. As the placenta develops, these small clots can cause clogging that restricts or stops the flow of blood and nutrients to the fetus, which can result in first trimester miscarriage, placental abruption, intrauterine growth restriction, or stillbirth.

Treatment of Blood Clotting Disorders to Prevent Pregnancy Loss

Treatment for blood clotting disorders during pregnancy includes anti-coagulation medications such as Lovenox, heparin, or low-dose ASPIRIN®. Depending on the type and severity of the disorder, Lovenox or heparin will be given as injections once or twice a day. If Lovenox is used throughout pregnancy, the medication must be switched to heparin prior to delivery to prevent epidural complication. Low-dose ASPIRIN® helps to thin the blood, and is usually recommended to be continued as a daily treatment after pregnancy.

An obstetrician alone may not be qualified to treat the high-risk pregnancy of a patient with a clotting disorder. Often, a referral is given to the patient to be evaluated by a perinatologist and a consultation with a hematologist may be necessary.

Strict and careful fetal monitoring is necessary throughout the pregnancy to prevent and correct any signs of intrauterine growth restriction or fetal distress, and the equipment is just not available in most obstetrician’s office. A perinatologist will often work in conjunction with a primary obstetrician, and may entirely replace the obstetrician when needed in sever cases, to ensure a positive outcome and healthy pregnancy.

If you suspect you suffer from a clotting disorder, simple blood tests that include a genetic testing component are needed to confirm the suspicion. After diagnosis, your chances of conceiving and carrying to term are greatly increased through the use of medication and through the sympathetic and knowledgeable guidance of a qualified perinatologist.


Mayo Clinic. “Blood Clotting Disorders and Pregnancy

American Society of Hematology. “Blood Clots

Georgia Reproductive Specialist. “Thrombophilia: Another Factor to Consider in Cases of Recurrent Pregnancy Loss