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Dose Adjusting Enoxaparin Thromboprophylaxis Dosage According to Anti-factor Xa Plasma Levels Improve Pregnancy Outcome

This study has been completed.
Information provided by (Responsible Party):
Raed Salim, HaEmek Medical Center, Israel Identifier:
First received: January 20, 2010
Last updated: February 20, 2016
Last verified: February 2016

The risk of venous thromboembolism increases in pregnancy. Thrombophilia whether genetic or acquired, is a hypercoagulable disorder that may increase the risk of venous thromboembolic events. Clinically, these events are presented as maternal deep vein thrombosis and pulmonary emboli. Thrombophilias are also associated with adverse fetal outcomes including intrauterine growth restriction, intrauterine fetal death, severe preeclampsia, placental abruption and recurrent abortions.

Pregnant women who experienced one or more of the above complications are advised to be examined for the presence of the genetic or the acquired form of thrombophilia.

Low molecular weight heparin prophylaxis, an anticoagulant, is advised for pregnant women with a history of thromboembolism, and many experts recommend prophylaxis for pregnant patients with a known thrombophilia and history of adverse pregnancy outcomes associated with these hypercoagulable states.

Physiologic changes in normal pregnancy, including weight gain, increased renal clearance and volume of distribution, may decrease the availability of low molecular weight heparin (Enoxaparin or Dalteparin), or produce a less predictable response in pregnant women compared with nonpregnant women. There are no clear recommendations for use of prophylactic low molecular weight heparin in pregnancy. Clinicians tend to use doses suggested for nonpregnant patients. Regarding pregnant patients taking enoxaparin or dalteparin, the American College of Obstetricians and Gynecologists states that "because of the lack of data regarding adequate dosing during pregnancy, anti-factor Xa levels may be monitored".

Two recently published studies demonstrated that plasma anti-factor Xa levels during pregnancy were lower than expected, indicating that many pregnant patients may receive a subprophylactic dosing.

Our objective is to check pregnancy outcome among thrombophilic women treated with an adjusted enoxaparin thromboprophylaxis dosage according to anti-factor Xa plasma levels compared to women with fixed dosage.

Condition Intervention
Fetal Demise
Fetal Growth Restriction
Abruptio Placentae
Drug: enoxaparin

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Prevention
Official Title: Dose Adjusting Enoxaparin Thromboprophylaxis Dosage According to Anti-factor Xa Plasma Levels Improve Pregnancy Outcome

Resource links provided by NLM:

Further study details as provided by Raed Salim, HaEmek Medical Center, Israel:

Primary Outcome Measures:
  • placental syndrome or thromboembolic event [ Time Frame: 9 months ]

Secondary Outcome Measures:
  • enoxaparin side effects [ Time Frame: 9 months ]

Enrollment: 144
Study Start Date: July 2009
Study Completion Date: August 2015
Primary Completion Date: January 2015 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
No Intervention: enoxaparin fixed
enoxaparin dosage will be fixed during pregnancy
Experimental: enoxaparin adjusted
enoxaparin dosage will be adjusted according to anti-factor Xa plasma levels
Drug: enoxaparin
enoxaparin dosage will be adjusted according to anti-factor Xa plasma levels


Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No

Inclusion Criteria:


  • Singleton gestation
  • A history of fetal demise, fetal growth restriction, placental abruption, preeclampsia, recurrent abortions or maternal thromboembolic event.
  • Acquired or congenital thrombophilia treated with low molecular weight heparin

Exclusion Criteria:

  • Women treated empirically with low molecular weight heparin
  • Women with a history of pregestational diabetes.
  • Significant polyhydramnios or oligohydramnios, major fetal structural, generic or chromosomal malformations
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Please refer to this study by its identifier: NCT01068795

Dep. OB/GYN, HaEmek Medical Center
Afula, Israel
Sponsors and Collaborators
HaEmek Medical Center, Israel
Principal Investigator: Raed Salim, MD Dep. OB/GYN, HaEmek Medical Center, Afula, Israel
  More Information

Responsible Party: Raed Salim, MD, HaEmek Medical Center, Israel Identifier: NCT01068795     History of Changes
Other Study ID Numbers: 0048-09-EMC ANTIXA-02
Study First Received: January 20, 2010
Last Updated: February 20, 2016

Keywords provided by Raed Salim, HaEmek Medical Center, Israel:
placental syndrome
maternal thromboembolic event
anti-factor Xa

Additional relevant MeSH terms:
Fetal Growth Retardation
Fetal Death
Abruptio Placentae
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Hypertension, Pregnancy-Induced
Pregnancy Complications
Fetal Diseases
Growth Disorders
Pathologic Processes
Obstetric Labor Complications
Placenta Diseases processed this record on May 25, 2017