Women , Contraception , Pregnancy and the risk of Thrombosis !!!!
Venous thromboembolism (VTE) is a term used to describe blood clots that develop in the veins, such as a deep vein thrombosis (DVT) of the deep leg veins, or a blood clot that has traveled to the lungs called a pulmonary embolism (PE). Pregnancy increases the chance of developing VTE by about four- to fivefold
For a woman who has had VTE, a pregnancy is high risk, so family planning is especially important. A woman and her partner should decide whether they want to have children (or want to have any more children), and if so, when.
For women who have had DVT or PE, what are the risks of pregnancy?
Most women who have had DVT or PE can have a healthy pregnancy, but they should be conscious of the risks, should consult knowledgeable physicians, and should plan accordingly. DVT and PE comprise VTE. Women of childbearing age who have had VTE in the past have a 1–2% chance of developing a blood clot each year.
Therefore, most women who have had VTE, even if they are not on anticoagulants prior to pregnancy, will be prescribed anticoagulants during pregnancy and for the 6 weeks after childbirth to reduce the risk of another VTE.
How is VTE treated or prevented during pregnancy?
Heparin and low molecular weight heparin (LMWH) (e.g. enoxaparin/Lovenox®) are the anticoagulants used to treat and prevent VTE during pregnancy. They are considered safe because neither crosses the placenta or enters the circulation of the baby in the uterus. Heparin and LMWH have been used to treat thousands of pregnant women with no increased risk of birth defects or bleeding problems in their babies.
In fact, in women who have antiphospholipid syndrome (an immune disorder that increases the risk of blood clots), heparin has actually been shown to improve the outcome of pregnancy. Women are sometimes concerned about having to give themselves injections into their abdomens while they are pregnant. They need not be concerned – the needle is very short and never goes below the fatty layer of tissue under the skin.
Warfarin and the new oral anticoagulants (NOACs) are not considered safe in pregnancy. Warfarin crosses the placenta and increases the risk of birth defects. Also, up to 30% of women who take warfarin during early pregnancy have a miscarriage, approximately 7% have a baby with a birth defect, and approximately 7% have a stillborn baby.
Although there are some exceptional circumstances in which warfarin may be the preferred anticoagulant during pregnancy, women are generally advised not to take it. The NOACs – dabigatran, rivaroxaban, apixaban, and edoxaban – also cross the placenta. Whether they increase the risk of birth defects is unknown, but they should not be used in pregnancy.
At present, if a woman becomes pregnant while taking warfarin or one of the NOACs, she should switch to LMWH as soon as the pregnancy is confirmed. The dose will be once or twice daily injections of a full or therapeutic dose of LMWH. Because pregnancy causes LMWH to be cleared from the circulation more quickly, many providers prefer to prescribe two injections a day. This dosing is the same treatment that a woman would receive if she developed a new blood clot during pregnancy. Women who had VTE in the past, but were not taking warfarin or a NOAC prior to pregnancy, will likely need to take LMWH during pregnancy, but usually a lower or prophylactic dose. Even if a lower dose is used, the same precautions are required at the time of miscarriage or childbirth to reduce the risk of bleeding.
Do women who are taking anticoagulants need to switch to LMWH while trying to get pregnant?
Women who become pregnant while taking warfarin have a significantly higher rate of miscarriage than women who are not taking warfarin (up to 30% compared to 15%).The rate of miscarriage for women who become pregnant while taking one of the NOACs is unknown. Women who become pregnant while taking LMWH have no increased risk of miscarriage. For this reason, some women, after talking to their providers, decide to switch to LMWH while trying to become pregnant.
For women who are taking anticoagulants, what precautions are taken at the time of miscarriage or childbirth?
Because heparin or LMWH may increase the risk of bleeding complications if it is in the mother’s system at the time of miscarriage or childbirth, precautions are taken to reduce the risk of bleeding. Traditional ‘unfractionated’ heparin, which does not last as long in the circulation, may be substituted for LMWH during the last few weeks of pregnancy and stopped temporarily when labor starts. Alternatively, LMWH may be continued and stopped temporarily in anticipation of childbirth, or surgery for late miscarriage or other termination of pregnancy. Surgery for early miscarriage or other termination of pregnancy carries little bleeding risk and usually does not require discontinuation of anticoagulation. When anticoagulation is stopped temporarily at the time of childbirth, women can wear pneumatic compression devices (inflatable sleeves worn on the legs that inflate and deflate to help improve circulation in the veins) to help prevent VTE.
Because bleeding in the epidural space or spinal canal could compress the spinal cord and cause paralysis, anesthesiologists will usually wait to place an epidural or spinal anesthetic until a woman has been off heparin for more than 6 hours, low-dose LMWH for more than 12 hours, or full-dose LMWH for more than 24 hours. If a woman needs pain relief during labor and has heparin or LMWH in her system, she can receive opioid pain relievers (such as fentanyl) instead of an epidural. If a woman requires a cesarean delivery and has heparin or LMWH in her system, she can receive a general anesthetic instead of a spinal anesthetic.
Anticoagulation is usually not restarted until 12–24 hours after childbirth. A woman who only needs anticoagulation for the 6 weeks after childbirth may stay on LMWH for the entire 6 weeks. LMWH is safe during breastfeeding. Women who require long-term anticoagulation and are breastfeeding can be converted to warfarin 1–2 weeks after childbirth, when the risk of major bleeding has subsided and it is safe to take overlapping anticoagulants. Warfarin is safe during breastfeeding as very little warfarin appears in breastmilk and what little does appear has never been shown to affect a baby. The degree to which the NOACs appear in breastmilk is unknown. Women who require long-term anticoagulation and are not breastfeeding can start a NOAC after childbirth. If they are breastfeeding, they can start a NOAC after weaning.
And Now …. What are the options for family planning and contraception for a woman with a history of VTE?
There are multiple options for family planning and contraception depending on whether a woman and her partner want to have children or not. If a woman and her partner never want to have children (or never want to have any more children), sterilization is an option. Female sterilization is achieved by interruption of the fallopian tubes (tubal ligation). Half of the time, this procedure is performed after childbirth – while the abdomen is still open after cesarean delivery or through a small abdominal incision after vaginal delivery. When not performed after childbirth, tubal ligation is usually performed through the abdomen with a laparoscope. Male sterilization, or vasectomy, is performed under local anesthesia; it is safer, more effective, and less expensive than female laparoscopic tubal ligation. If a woman and her partner want to have children, but do not want to have them anytime soon, the woman should choose a long-acting, reversible method of birth control such as an intrauterine device (IUD) or subcutaneous implant. If a woman and her partner want to have children soon, they can choose from a variety of hormonal and non-hormonal methods including birth control pills, natural family planning, spermicides, and barrier methods.
Planning a pregnancy is complicated by the fact that hormonal methods of birth control may increase the risk of VTE. Non-hormonal methods of birth control do not increase the risk of developing a blood clot, but with the exception of the copper IUD, they are not particularly effective. Besides the copper IUD, these methods include natural family planning; spermicides (foam, jelly or suppositories); and the barrier methods – diaphragm, cervical cap, and condoms. Importantly, condoms are the only birth control method that prevents sexually transmitted infections. With the exception of the copper IUD, the failure rate of these methods ranges from 12% to 32%. The IUD (either the copper or the levonorgestrel IUD) has a failure rate of less than 1%. Unfortunately, the copper IUD may increase menstrual blood flow, which could potentially be a problem for women on anticoagulation.
Let us know …What are the risks with hormonal methods of birth control?
Birth control pills are the most popular method of birth control in the United States. They contain the hormone estrogen and/or the hormone progestin (synthetic progesterone). Birth control pills and other hormonal methods of birth control not only prevent pregnancy, but also reduce menstrual blood flow, an advantage for women on anticoagulation. Unfortunately, birth control pills that contain both estrogen and progestin increase the risk of VTE two- to sixfold. Hormone patches and rings, which also contain estrogen and progestin, increase the risk even more. probably because the hormones are absorbed continuously. Estrogen is believed to be the hormone responsible for the increased risk of VTE, but progestins play a role, too. The risk of VTE is markedly reduced by anticoagulation, so, in most cases, women who have had VTE and are taking anticoagulants can safely take birth control pills. Women who have had VTE and are not taking anticoagulants should avoid estrogen-containing contraceptives, but progestin-only methods are available.
Most progestin-only contraceptives do NOT increase the risk of VTE. Injections contain a higher concentration of progestin and increase the risk of VTE two- to fourfold, but progestin-only pills, the levonorgestrel IUD, and the subcutaneous implant do not. Therefore, progestin-only pills, the levonorgestrel IUD, and the subcutaneous implant are generally safe methods of birth control for a woman who has had VTE. Progesterone injections are no longer recommended for a woman who has had VTE and is not on anticoagulation.
And Finally ,, Take our Home Message :
Pregnancy and the use of pregnancy hormones (estrogen and progestin) in hormonal contraceptives increase the risk of developing blood clots. Women with a history of VTE, whether or not they are on anticoagulation, should be aware of these increased risks and, with their partners and their physicians, have a plan in place for pregnancy and contraception.
No change log.