There may be a ticking time bomb in your veins. It's rare, potentially deadly, hereditary, and worst of all, it's most dangerous to expecting and new mothers. It's called Hereditary Antithrombin (AT) Deficiency. It is among the rarest, most dangerous, and most underdiagnosed of all inherited blood clotting disorders. And it's highly unlikely that your OBGYN will test you for it. The statistics are sobering: patients with Hereditary AT Deficiency have a 20-fold higher risk of blood clots, such as deep vein thrombosis (DVT) or pulmonary embolism (PE). One in three pulmonary embolisms may be fatal. Unfortunately, if you're pregnant, the risk increases even further.In fact, up to 70% of women with Hereditary AT Deficiency who do not receive preventative treatment may experience blood clotting before or after the birth.