Background
Aspirin is offered to pregnant women to prevent preeclampsia, a severe obstetrical
complication. Large studies of nonpregnant populations have consistently shown that
aspirin prophylaxis increases the risk of hemorrhagic complications. However, there
have not been any population-based studies investigating this in a pregnant population.
Objective
This study aimed to investigate whether aspirin use during pregnancy is associated
with an increased risk of bleeding complications.
Study Design
We performed a register-based cohort study using the Swedish Pregnancy Register wherein
we examined 313,624 women giving birth between January 2013 and July 2017. Logistic
regression was used to assess the risk of antepartum, intrapartum, and postpartum
hemorrhage. A propensity score and inverse probability treatment weighting was used
to generate an odds ratio that corrects for differences in baseline characteristics.
Results
Aspirin use was registered in 4088 (1.3%) women during pregnancy. Compared with women
who did not take aspirin, aspirin use was not associated with bleeding complications
during the antepartum period (adjusted odds ratio, 1.22; 95% confidence interval,
0.97–1.54). However, aspirin users had a higher incidence of intrapartum bleeding
(2.9% aspirin users vs 1.5% nonusers; adjusted odds ratio, 1.63; 95% confidence interval,
1.30–2.05), postpartum hemorrhage (10.2% vs 7.8%; adjusted odds ratio, 1.23; 95% confidence
interval, 1.08–1.39), and postpartum hematoma (0.4% vs 0.1%; adjusted odds ratio,
2.21; 95% confidence interval, 1.13–4.34). The risk of a neonatal intracranial hemorrhage
was also increased (0.07% vs 0.01%; adjusted odds ratio, 9.66; 95% confidence interval,
1.88–49.48). After stratifying by mode of birth, a higher incidence of bleeding among
aspirin users was present for those who had a vaginal birth but not those who had
a cesarean delivery.
Conclusion
Using aspirin during pregnancy is associated with increased postpartum bleeding and
postpartum hematoma. It may also be associated with neonatal intracranial hemorrhage.
When offering aspirin during pregnancy, these risks need to be weighed against the
potential benefits.
Key words
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Article info
Publication history
Published online: July 17, 2020
Accepted:
July 14,
2020
Received in revised form:
June 21,
2020
Received:
February 2,
2020
Footnotes
Drs Hastie and Tong contributed equally to this work and are considered co-first authors.
Drs Hesselman and Bergman contributed equally to this work and are considered co-senior authors.
The authors report no conflict of interest.
This study was approved by the Uppsala Ethics Board on August 15, 2018 (approval number: 2018/287).
The National Health and Medical Research Council of Australia provided salary support to R.H. (#1176922) and S.T. (#1136418). The Center for Clinical Research provided salary support to S.H. (#CKFUU744551) and L.B. (#CKFUU740361).
Cite this article as: Hastie R, Tong S, Wikström AK, et al. Aspirin use during pregnancy and the risk of bleeding complications: a Swedish population-based cohort study. Am J Obstet Gynecol 2021;224:95.e1-12.
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