Coagulation Disorders

Like autoimmune disorders, the role of coagulation disorders (blood clotting) in fertility is pretty controversial in our field. Basically, if you’re prone to blood clots, clotting can occur between your uterus and placenta. That can disrupt the egg’s implantation, possibly causing an early miscarriage. Fertility treatments can also increase your chances of blood clotting, which can be dangerous to you and your baby.

How it’s tested

You know how many women take birth control pills for various reasons, like birth control, facial acne or menstrual pain? Unfortunately, birth control pills can cause a blood clot in small minority of these women. It seems to be related to how the pill alters your natural estrogen levels.

The same can happen during pregnancy, when your estrogen levels are fluctuating a lot: a small but real minority of women will develop blood clots either during or immediately after delivery. These clots often appear as a “deep veined thrombosis”, sometimes with symptoms like calf pain and swelling as the clot grows. The clot can break off and get stuck in the lungs, making it hard to breathe. That’s called a “pulmonary embolism”.

It’s also possible for these blood-clot-prone pregnant women to have subtle clotting between their uterus and placenta, well before clots develop in the legs. This can disrupt the egg’s implantation, possibly causing an early miscarriage.

In other words, blood clot disorders are a serious concern. And what worries us is that a lot of fertility treatments will mess with your estrogen levels, just like the birth control pill or being pregnant do. The last thing we want is for your fertility treatment or pregnancy to trigger a blood clot!

For doctors, the tricky part is figuring out which women are more likely to get these blood clots, and which test (there’s a lot of them!) is most appropriate for which woman.

There are many blood-clotting tests, all intended for pretty specific cases. So we strongly suggest you talk with your doctor and make a decision together on which screening tests are right for you.

How it’s treated

If your doctor suspects you might have a blood-clotting disorder (maybe because of your personal or family history, or your test results) he or she will likely recommend treatment.

In the past, women took about 81mg of aspirin everyday to reduce their chances of blood clotting – even if they had no reason to believe they had a clotting disorder. But that’s no longer recommended, because many studies have documented that it’s ineffective.

So if a true blood-clotting disorder is discovered, we usually recommend “low-molecular-weight heparins” like Lovenox and Fragmin. These are taken at low, preventative doses. They can help minimize the risk of blood clotting, and possibly even boost your chances of a successful egg implantation.

However, we’re still pretty cautious with those medications. There could be side effects, so we don’t recommend taking them unless there is a clear suggestion to do so from your clinical team.


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