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APS and Pregnancy

Antiphospholipid syndrome (APS) is an illness that involve the immune system, and causes increased clotting of the blood. Normally antibodies, chemicals made by the immune system, are helpful in fighting germs or viral infections from outside the body. However in APS, the immune system makes antibodies that cause blood to clot abnormally. This may cause problems with the pregnancy.

  • The diagnosis of APS is very difficult, and also controversial among doctors.

  • There are 3 blood tests that are commonly used, and accepted by most physicians.

  • As many as 15 blood tests for antiphospholipids are available; however, there is little evidence that patients who are positive by the “extra” blood tests are at increased risk for pregnancy problems.

  • The problem is that 2% of all pregnant women have positive blood tests. Most of these women never have problems with abnormal pregnancy outcomes and treating them would expose them to the side effects of the treatment without benefit.

  • Therefore, diagnosis involves more than blood tests.

  • There must be “clinical signs” medical problems that have already occurred in addition to the abnormal blood tests.

  • The clinical signs are a history of blood clots in a large vein or in an artery, three or more consecutive miscarriages, low platelet count, anemia caused by blood being broken down in the blood stream, stroke, and still birth.

  • The levels of antibody can go up and down, and even disappear, so to definitely say someone has APS, the blood tests need to repeated at least 8 weeks from the first and still be positive. The decision on treatment at a particular time (such as pregnancy) depends upon the levels and what the previous medical problems were.



APS Impact on Pregnancy

  • The manifestations of APS are variable. Most people will not have more than one of these problems.

  • Recurring miscarriage

  • Preeclampsia

  • Insufficient function of the placenta causing poor growth of the baby and/or inability of the baby to tolerate labor

  • Blood clot in an artery or large vein either during the pregnancy, or up to six weeks after the baby is born

  • Stillbirth

  • A very rare APS condition exists of a severe postpartum illness with fever and heart, lung and kidney failure and multiple blood clots.


Pregnancy Impact on APS

Patients with APS are more prone to blood clots during pregnancy and up to 6 weeks after pregnancy. The blood clots may migrate to the lungs which is a very serious and life threatening event.

Special Prenatal/Birth/Neonatal Considerations
Ideally, one should seek medical advice before becoming pregnant. When you get pregnant it is important to be referred to your Obstetrician as early as possible to decide on the need for treatment with aspirin or heparin.

Once pregnancy is achieved, frequent office visits will be needed to:

  • Screen for preeclampsia,

  • Monitor the fetus with either nonstress test or biophysical profile

  • Ultrasound examinations every 3-4 weeks to check the growth of the baby.

  • For patients on heparin, extra blood tests may be needed to adjust the dose depending on the type of heparin being used, and the past history of the patient.

  • Patients on low molecular weight heparin may not be able to have epidural or spinal anesthesia.


Treatment of APS during pregnancy involves low dose aspirin and/or heparin

  • 1 baby aspirin (80 mg)/day is usually started as soon as pregnancy is diagnosed

  • Heparin injections are usually started at 8 weeks. Not all patients with APS need heparin.

  • Heparin is a blood thinner. It can only be given by injection. The needle is very thin, and is put just under the skin. Most patients can do this by themselves.

The effects of heparin depend on the dose given

  • In “therapeutic doses” the blood does not clot, and women will bruise and bleed easily.

  • In “prophylactic doses”, the blood clots normally and there is just bruising at the site of injection.

  • The dose used depends on the clinical problems from APS.



  • There are 2 types of heparin

    • Low molecular weight heparin

      • Is given once or twice a day.

      • It is almost 10 times as expensive as regular heparin.

      • It lasts longer than regular heparin so epidural anesthesia cannot be used unless 24 hours has elapsed since the last injection.

    • Unfractionated or regular heparin

      • It is given 2 – 3 times a day.

      • It costs much less than low molecular weight heparin.

      • It has a higher chance of causing low platelets as a side effect than does low molecular weight heparin.

      • If only “prophylactic” doses are used, there is no problem with epidural anesthesia.
  • “When Pregnancy Isn’t Perfect: A Layperson’s Guide to Complications in Pregnancy” By Laurie A. Rich.
  • “Pregnancy Bedrest: a Guide for the Pregnant Woman and Her Family”, by Susan H. Johnston, M.S.W. & Deborah A. Kraut, M.I.L.R.
  • Sidelines at 800-876-3151 or http://www.sidelines.org – for full listings of Resources for High-Risk Parents

Written by:
Michele R. Lauria, MD, MS
Division of Maternal-Fetal Medicine
Dartmouth Hitchcock Medicine Center, Lebanon, NH
Copyright © 2005 Dartmouth-Hitchcock Medical Center;
One Medical Center Drive, Lebanon, NH 03756

Copied with permission by Dartmouth-Hitchcock Medical Center & the author.
Please contact them for re-printing permissions on this article.

Our Mission

Founded in 2005, the APS Foundation of America, Inc. is dedicated to fostering and facilitating joint efforts in the areas of education, public awareness, research, and patient services for Antiphospholipid Syndrome (APS) in an effective and ethical manner.


APS Foundation of America, Inc.
P. O. Box 801
LaCrosse, WI 54602-0801

DISCLAIMER: APS Foundation of America, Inc. website is not intended to replace standard doctor-patient visits, physical examination, and medical testing. Information given to members is only an opinion. All information should be confirmed with your personal doctor. Always seek the advice of a trained physician in person before seeking any new treatment regarding your medical diagnosis or condition. Any information received from APS Foundation of America, Inc. website is not intended to diagnose, treat, or cure. This site is for informational purposes only. Please note that we will be listing all donor or purchaser's names on the Donor page of our foundation site. If you do not want your name listed, please contact us to opt out. If you think you may have a medical emergency, call your doctor or 911 immediately.