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Premature infants have increased blood clot risk through young adulthood

According to a large new study, infants born prematurely have an increased risk of venous thromboembolism through young adulthood
According to a large new study, infants born prematurely have an increased risk of venous thromboembolism through young adulthood
Robin Wulffson, MD

Venous thromboembolism is defined as a formation of a blood clot in a vein. A common location for the blood clot is the calf. These clots can break loose and travel to the lungs (pulmonary embolus); this can result in death. According to a large new study, infants born prematurely have an increased risk of venous thromboembolism through young adulthood. The study was published online on July 28 in the journal Pediatrics by researcher at Stanford University School of Medicine (Stanford California) and Lund University (Malmö, Sweden).

The study authors note that preterm birth has been associated with increased risk of venous thromboembolism in infancy; however, the longer-term risk is unknown. Therefore, they conducted a study to assess this association from birth through young adulthood.

The study group comprised 3,571,574 individuals who were live-born in Sweden from 1973 through 2008; this group included 206,844 born preterm (gestational age less than 37 weeks), and followed up through 2010 (ages 0–38 years). The main outcome measurement was a venous thromboembolism.

The investigators found that 7,519 (0.2%) of the study group were diagnosed with a venous thromboembolism during 70.8 million person-years of follow-up. Low gestational age at birth was associated with a venous thromboembolism in infancy (ages less than 1 year; 47.16-fold increased risk for 22 to 27 weeks, 5.54-fold increased risk for 28 to 33 weeks, 3.54-fold increased risk for 34 to 36 weeks, 1.00 for 37 to 41 weeks (reference)). For early childhood (ages 1–5 years) and young adulthood (ages 18–38 years, the risk was 2.76-fols for 22 to 27 weeks, 1.53-fold for 28 to 33 weeks, 1.24-fold for 34 to 36 weeks, and 1.00 for 37 to 41 weeks (reference), but not in late childhood (ages 6–12 years). Very preterm (less than 34 weeks) but not late preterm birth (34–36 weeks) was also associated with venous thromboembolism VTE in adolescence (ages 13–17 years). After further adjustment for comorbidities (other health problems), these associations were reduced; however, they remained significantly elevated.

The authors concluded that low gestational age at birth was associated with increased risk of a venous thromboembolism in infancy, early childhood, and young adulthood.

Deep vein thrombosis occurs without symptoms about 50% of the time. When symptoms do occur, they may include:

  • Swelling in the leg
  • Red, discolored, or white skin
  • Rapid heartbeat (tachycardia)
  • Slight fever
  • Warm skin
  • More visible surface veins
  • Dull ache, tightness, tenderness or pain in the leg (these symptoms may only occur while walking or standing)

The symptoms of deep vein thrombosis may resemble other medical conditions or problems. Always consult a physician for a diagnosis. The goal of treatment is to prevent the clot from growing, to ensure that it doesn't break off and travel through the veins to the lungs, and to help reduce the possibility of another blood clot forming. Treatment may include:

Medications. Various types of medications may be used in the treatment of DVT. Although anticoagulants (blood thinners) do not destroy the clots, they may keep the clot from growing and other clots from forming. Oral blood thinners (i.e., warfarin (Coumadin) or Xarelto) may be taken orally or a heparin injection may be given either intravenously or under the skin (subcutaneously). Treatment with blood thinners may last 6 months or more. If a blood clot develops after surgery, treatment may be shorter. If there have been previous clots or treatment for another illness is underway, the treatment may last as long as risk factors are present.