Research
Basic science: Obstetrics
Incidence and risk patterns of venous thromboembolism in pregnancy and puerperium—a register-based case-control study

https://doi.org/10.1016/j.ajog.2007.08.041Get rights and content

Objective

This study was undertaken to estimate the incidence of venous thromboembolism in pregnancy and puerperium and to identify risk factors for pregnancy-related venous thromboembolism.

Study Design

A register-based case-control study with 613,232 pregnancies from 1990-2003 in 11 Norwegian counties. Medical records for eligible cases were revisited and relevant medical data were transferred to a specific case-report form. The diagnosis of venous thromboembolism was based on strict criteria. Data were analyzed by χ2 test and forward stepwise logistic regression.

Results

In total, 615 cases were detected. The incidence of venous thromboembolism was 1 per 1000 pregnancies. The ante- and postnatal incidences were quite similar. Antenatal risk factors were assisted reproduction, gestational diabetes, age older than 35 years, multiple pregnancies, and primi-parity. Postnatal risk factors were cesarean section, preeclampsia, assisted reproduction, abruptio placenta, and placenta previa.

Conclusion

We found different ante- and postnatal risk patterns. Assisted reproduction and gestational diabetes were significant antenatal risk factors; whereas cesarean section and preeclampsia were strong postnatal risk factors.

Section snippets

Materials and Methods

From Jan. 1, 1990-Dec. 31, 2003, women with a diagnosis of VTE in pregnancy or postpartum in 18 hospitals in 11 of 19 Norwegian counties were identified through selected ICD-9 and -10 code search in the Norwegian Patient Register (Table 1 and Figure 1). In addition, ascertainment of case identification in the Norwegian Patient Register was validated for the entire study period by data on VTE in pregnancy at 3 major Norwegian hospitals (Ullevål University Hospital, Haukeland University Hospital,

Results

We identified 615 cases with objectively confirmed VTE. Five hundred and ninety-five cases were identified in the Norwegian Patient Register, and another 20 patients were only identified in the Medical Birth Registry of Norway. The incidence of pregnancy-related VTE was 1.0 per 1000 pregnancies with no difference in antenatal and postnatal incidences (Table 2). DVT was more common antenatally than postnatally (0.43 vs 0.30 per 1000 deliveries, respectively), whereas PE displayed higher

Comment

The crude incidence rate of VTE associated with pregnancy was 1.0 per 1000 deliveries. The incidences of ante- and postnatal VTE were similar, but the risk pattern differed. Antenatal risk factors seemed to be related to the woman’s constitutional conditions such as age, parity, numbers of fetuses, and way of conception, whereas postnatal risk factors seemed to be correlated to maternal morbidity and complications during and after delivery. The postnatal risk factors such as preeclampsia,

Cited by (0)

This study was supported by grants from the Norwegian Research Council (Grant 160805-V50, fellowship to A.F.J.) and the Eastern Norway Regional Health Authority Trust, Hamar, Norway.

Cite this article as: Jacobsen AF, Skjeldestad FE, Sandset PM. Incidence and risk patterns of venous thromboembolism in pregnancy and puerperium—a register-based case-control study. Am J Obstet Gynecol 2008;198:233.e1-233.e7.

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