How Often Are Factor XIII Infusions in Pregnancy?

If you have Factor XIII (FXIII) deficiency, your prophylaxis infusion (preventative treatment) schedule will change significantly if you become pregnant. While you may be accustomed to receiving infusions once a month, during pregnancy, you will likely need infusions every two weeks, or even more frequently, as your pregnancy progresses ^[1][2].

Why Does the Schedule Change?

During pregnancy, your body undergoes major physiological changes, including a significant expansion of your blood volume, particularly in the second and third trimesters ^[1][3]. Because you have more blood circulating in your body, the FXIII factor you infuse is diluted and consumed much faster than when you are not pregnant ^[1][2]. Therefore, more frequent doses—and sometimes higher dosage amounts—are needed to keep your factor levels steady.

Target Trough Levels

To protect both you and your baby, your medical team will monitor your trough levels—the lowest amount of FXIII in your blood just before your next scheduled dose ^[1][4].

Factor XIII is essential not only for normal blood clotting but also for proper placental attachment and for maintaining the pregnancy ^[5][6]. The goal is typically to maintain your trough levels above 30%, though your specific target may evolve depending on your trimester ^[3][5]. Falling below your target threshold increases the risk of serious complications, such as placental abruption (when the placenta separates from the uterus) and miscarriage (early fetal loss) ^[5][7].

Always contact your medical team immediately or go to the emergency room if you experience warning signs such as vaginal bleeding, unusual spotting, or severe abdominal cramping.

Personalized Monitoring

Because every woman’s body processes the infused factor differently, there is no single “one-size-fits-all” schedule ^[2]. Your hematologist and high-risk obstetrician will work together to create a personalized treatment plan ^[3][8]. This will require frequent blood tests to monitor your trough levels and ensure your infusion schedule is keeping up with your body’s increasing demands ^[1][4].

Labor, Delivery, and Postpartum Care

Your personalized plan will not stop at pregnancy. Because labor and delivery present significant bleeding risks, your care team will also establish a highly specific dosing strategy for childbirth and the immediate postpartum period to protect you from postpartum hemorrhage ^[9][10].

While a high-risk pregnancy can feel daunting, with strict adherence to your infusion schedule and close monitoring by your medical team, a successful, healthy pregnancy is very achievable ^[2][7].