Will continuing aspirin (acetylsalicylic acid) 150mg daily until delivery increase the risk of excessive bleeding during a cesarean section at 35 weeks in a morbidly obese patient with a twin pregnancy and selective fetal growth restriction (sFGR)?

Aspirin 150mg Can Be Safely Continued Until Delivery at 35 Weeks for Cesarean Section

Low-dose aspirin at 150mg daily should be continued until delivery at 35 weeks, as this dose does not cause excessive bleeding during cesarean section and provides critical protection against preeclampsia throughout the high-risk period in this morbidly obese patient with twin pregnancy and selective fetal growth restriction. 1, 2

Evidence Supporting Continuation Until Delivery

Safety Profile Through Delivery

• Low-dose aspirin (including doses up to 150mg) does not increase risks of placental abruption, postpartum hemorrhage, or fetal intracranial bleeding when continued until delivery. 1, 3, 4
• Multiple international guidelines from the American College of Obstetricians and Gynecologists, along with guidelines from Canada, Ireland, New Zealand, and the UK, specifically recommend continuing aspirin daily until delivery rather than stopping at a predetermined gestational age. 1, 3, 4
• The rationale is that preeclampsia risk persists throughout pregnancy and into the early postpartum period, with eclamptic seizures potentially developing for the first time after delivery. 1

Specific Dosing for This High-Risk Population

• For morbidly obese patients with twin pregnancy, the recommended dose is 100-150mg daily, as morbid obesity reduces aspirin effectiveness and requires dose adjustment. 2
• Standard 81mg dosing has shown no benefit in high-risk populations including those with chronic hypertension and obesity, with some studies showing no difference in preeclampsia rates (34.3% vs 35.5%, p=0.79). 1
• International guidelines, including those from the European Association for the Study of the Liver, recommend 150mg aspirin for high-risk women. 1
• Twin pregnancies may show nonresponsiveness to lower doses, with 67% of twin pregnancy patients showing lack of response to 80mg aspirin according to platelet function testing. 5

Critical Timing Considerations

Why Stopping Early Is Harmful

• Stopping aspirin at 36 weeks "just to be safe" removes protection during a high-risk period and is not evidence-based. 1
• The American College of Obstetricians and Gynecologists explicitly advises against this practice, as preeclampsia risk continues through delivery. 1
• The FDA warning about aspirin in the third trimester refers to high doses (>100mg for analgesic purposes), not prophylactic low doses of 150mg or less. 1, 6

Optimal Management for Planned Cesarean at 35 Weeks

• Continue aspirin 150mg daily until delivery at 35 weeks without interruption. 1, 2
• The combination of twin pregnancy, selective fetal growth restriction, morbid obesity, and delivery at 35 weeks strongly favors planned cesarean delivery according to ACOG guidelines. 2
• For emergency cesarean section, aspirin continuation poses no additional bleeding risk. 1, 2

Important Caveats for Planned Cesarean with Spinal Anesthesia

If a scheduled cesarean section with spinal anesthesia is planned (rather than emergency), consider discontinuing aspirin 7-10 days before the procedure to allow adequate platelet recovery, and verify platelet count >75 × 10⁹/L immediately before spinal anesthesia. 2

However, this recommendation must be weighed against:

• The ongoing risk of preeclampsia development during those 7-10 days without aspirin protection 1
• The fact that at 35 weeks with sFGR, delivery timing may need to be expedited based on fetal monitoring and Doppler parameters 2
• Most evidence supports continuation until delivery for maternal and fetal benefit 1, 3, 4

Supporting Evidence from Guidelines

American College of Chest Physicians

• Aspirin 50-150mg daily was associated with a 17% decrease in preeclampsia risk, 14% reduction in fetal/neonatal death, and 10% reduction in small-for-gestational-age babies across 59 trials involving 37,560 women. 7

International Society for the Study of Hypertension in Pregnancy

• Recommends 150mg daily started before 16 weeks for women at increased risk, including those with multiple pregnancy and obesity. 7

Evidence-Based FGR Guidelines

• Low-dose aspirin 150mg in the evening demonstrated marked reduction in early-onset preeclampsia and reduction in small-for-gestational-age infants, with aspirin more effective when started at 16 weeks and in doses of 100mg compared to 60mg. 7

Clinical Bottom Line

The 150mg aspirin dose is appropriate for this high-risk patient and should be continued until delivery. The evidence overwhelmingly supports that this dose does not cause excessive bleeding during cesarean section, while stopping it prematurely removes critical protection against life-threatening maternal complications. 1, 2, 3, 4