出産後の血栓症リスクは少なくとも12週間持続する（Abstract: 216）

出産後12週間は通常よりも血栓症リスクが高い状態が持続する

Blood clot risk remains higher than normal for at least 12 weeks after delivering a baby

女性の血栓症リスクは出産後少なくとも12週間（これまで考えられていたよりも2倍長い）は高い状態が持続するとの大規模スタディの結果が2014年American Stroke Association's International Stroke Conferenceで発表された。研究者らは、2005～2010年にカリフォルニアの病院に出産のために入院した女性1,687,930人のデータを用いて血栓症の確率を算出した。これらの女性のうち1,015人がその後1.5年の間に血栓症を発症した。これらの中には脳卒中、心筋梗塞、肺塞栓症または深部静脈血栓症などを引き起こした血栓症患者が含まれた。血栓症発症のリスクは、血小板や他の血液凝固因子が増加する妊娠中に上昇する。リスクは出産時辺りにピークとなるが、今回その後0～6週間は10.8倍、7～12週間は2.2倍、13～18週後は1.4倍（有意ではない上昇）高い状態が持続することが明らかにされた。19～24週後までに血栓リスクは出産をしなかったのと同等のレベルに戻った。出産後6～12週に妊娠に関連した血栓症を発症するのは10,000人に1人未満である。

Women's risk for thrombosis remains elevated for at least 12 weeks after childbirth — twice as long as previously recognized, according to a large study presented at the American Stroke Association's International Stroke Conference 2014.

The chance of thrombosis rises during pregnancy, when platelets and other blood-clotting factors increase. The risk peaks around the time of delivery, but researchers found that afterwards it remained:

10.8 times higher during weeks 0-6;
2.2 times higher during weeks 7-12; and
1.4 times higher (a non-significant rise) during weeks 13-18.

By weeks 19-24, the chance of a blood clot returned to what it would have been if a woman had not given birth.

Fewer than one in 10,000 women suffer a pregnancy-related blood clot six to 12 weeks after delivery.

"While rare, blood clots are a serious cause of disability and death in pregnant and post-partum women, and many members of our research team have cared for young women with these complications," said Hooman Kamel, M.D., lead researcher and assistant professor in the Department of Neurology and the Brain and Mind Research Institute of Weill Cornell Medical College in New York City.

"If you have recently delivered a baby, seek medical attention if you develop symptoms such as: chest pain or pressure; difficulty breathing; swelling or pain in one leg; sudden severe headache; or sudden loss of speech, vision, balance, or strength on one side of your body."

The researchers calculated the odds using data on 1,687,930 women admitted for labor and delivery at a California hospital in 2005-2010. Of those, 1,015 women had a clot during the following 1.5 years. These included women with clots that caused a stroke, myocardial infarction, pulmonary embolism or deep vein thrombosis.

"Clinicians should consider our results when caring for high-risk postpartum patients, such as those with previous clots, or postpartum patients with symptoms concerning for thrombosis," Kamel said.

Co-authors are: Babak B. Navi, M.D.; Nandita Sriram, B.S.; Dominic A. Hovsepian, B.S.; and Mitchell S.V. Elkind, M.D., M.S.

The National Institute of Neurological Disorders and Stroke funded the study.