(HealthDay News) – The risk of venous thromboembolism (VTE) among pregnant women is highest if they have had a stillbirth and also increases if they are obese or have conditions such as varicose veins, inflammatory bowel disease, obstetric hemorrhage, preterm delivery, or cesarean section, according to a study published online April 2 in Blood.

Alyshah Abdul Sultan from the University of Nottingham in the United Kingdom, and colleagues examined the risk of antepartum and postpartum VTE using data from 376,154 pregnancies ending in live birth or stillbirth from 1995–2009.

The researchers found that during antepartum, there was a modestly higher risk of VTE associated with varicose veins, inflammatory bowel disease, urinary tract infection and pre-existing diabetes (absolute risks ≥139/100,000 person-year; incidence rate ratios ≥1.8). Postpartum, stillbirth greatly increased the risk of VTE (absolute risk = 2,444/100,000 person-years; incidence rate ratio = 6.2), while medical co-morbidities, body mass index (BMI) ≥30kg/m2, obstetric hemorrhage, preterm delivery, and cesarean section also increased VTE risk (absolute risks ≥637/100,000 person-years; incidence rate ratios ≥1.9).

“Our findings suggest that VTE risk varies modestly by recognized factors during antepartum, however women with stillbirths, preterm births, obstetric haemorrhage, caesarean section delivery, medical co-morbidities or BMI ≥30kg/m2 are at much higher risk of VTE following delivery,” the authors write.

One author reports receiving honoraria from drug companies for lectures and payment for an educational kit about obstetric thromboprophylaxis.

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