Prophylactic Enoxaparin Dosing for Prevention of Venous Thromboembolism in Pregnancy - a Prospective Randomized Trial

When pregnant patients are diagnosed by their physician as being at risk for VTE, they will
be offered a chance to discuss participation in the study prior to initiating prophylactic
Enoxaparin. The patient will be consented and then randomized, at that same clinic visit.
The patient will then have her chart flagged, and a randomization packet assigned to her.
The randomization packet will contain prescriptions for Enoxaparin. In arm 1, the
prescriptions will be for 40mg once daily. In arm 2, the prescriptions will be for 1mg/kg
once daily. As per routine care, the patient will be instructed by the clinic RN on how to
fill her prescription at the pharmacy, how to give herself the injection subcutaneously once
daily in the morning, and how to troubleshoot the injection process. As per routine care,
the patient will have the opportunity to ask all questions necessary about this process, and
her understanding and ability to comply with the injection procedures will be assessed by
the clinic RN. The patient will be given a new prescription each month at her regularly
scheduled MD appointment, from her randomization packet. At any time, as per routine care,
the patient can have the opportunity to review or troubleshoot the injection process with
the RN or MD in the clinic. At each clinic visit, approximately 1-2 times per month as per
routine care, the patient will be weighed and her weight recorded in her prenatal chart. At
each of these visits the patient will also be asked a series of questions as per the study
flowsheet in the chart, about potential side effects or adverse events she may have
experienced since her last visit. In addition, she will receive a phone call from one of the
study investigators once to twice per month to enquire about side effects, medication
tolerability, and medication compliance. At 3 predetermined intervals throughout the
pregnancy, the patient will be instructed to give a blood sample at the outpatient
laboratory. When at all possible, these blood draws will be coordinated to coincide with the
patient's regularly scheduled prenatal care blood draws, to minimize venipuncture episodes.
The study blood sample results will test for anti-XA level, which is a marker of the
effective prophylactic range of Enoxaparin, and serum creatinine, which is a marker of
kidney function and renal clearance of medication. These anti-XA level sample results will
be blinded to the medical care providers and to the patient, and used for research purposes
only. At or shortly after the patient reaches 36 weeks gestation, she will be switched from
enoxaparin to unfractionated heparin (UFH), as per standard of care to avoid any potentially
unexpected bleeding events associated with the onset of labor at term. When the patient
comes to the hospital for Labor and Delivery, routine labor and delivery care will ensue at
the discretion of the medical care team. 24 hours after delivery, or at the discretion of
the medical care team, the patient will be restarted on her Enoxaparin dosing arm, as per
standard of care. She will be instructed to continue the enoxaparin for 6 weeks, and will
receive a prescription from her randomization packet for this. The patient will return for a
6 week follow-up visit in the clinic as per standard of care, and a final study blood draw
will be performed at that time. If the patient misses her 6 week appointment, she will
receive a phone call to reschedule as per standard of care, and will be instructed over the
phone to discontinue her Enoxaparin and to come in for a blood draw.