Most IVF pregnancies follow the same aspirin guidelines as other high-risk pregnancies: continue low-dose aspirin until delivery or until your provider tells you to stop, typically no earlier than 36 weeks. There is no separate, IVF-specific stopping point. The timing depends on why you were prescribed aspirin in the first place, which can vary quite a bit in fertility treatment.
Why IVF Patients Take Aspirin
Aspirin serves different purposes at different stages of IVF, and the reason you’re on it shapes when you’ll come off it. Some clinics prescribe low-dose aspirin (75 to 100 mg) during ovarian stimulation to improve blood flow to the uterus and ovaries. In that context, aspirin is sometimes stopped as early as the day of the pregnancy test. The American Society for Reproductive Medicine does not strongly endorse this use and considers the evidence weak.
The more common reason to stay on aspirin into pregnancy is preeclampsia prevention. IVF conception itself is considered a moderate risk factor for preeclampsia, and many IVF patients carry additional risk factors like age over 35, a first pregnancy, obesity, or a history of high blood pressure. If your provider has you on aspirin for preeclampsia prevention, the timeline is longer and the guidance is clearer.
What Major Guidelines Recommend
The three most influential sets of guidelines (from ACOG in the U.S., NICE in the U.K., and the Royal College of Obstetricians and Gynaecologists) all agree: low-dose aspirin for preeclampsia prevention should be started between 12 and 16 weeks and continued daily until delivery. ACOG states explicitly that there is no apparent benefit to stopping low-dose aspirin before delivery.
That said, many older study protocols stopped aspirin at 36 weeks, and some providers still follow that convention. This is why you’ll hear conflicting advice. Both approaches, stopping at 36 weeks or continuing until delivery, are considered acceptable. Neither has been shown to cause harm in large studies.
The Case for Stopping at 36 Weeks
Providers who stop aspirin at 36 weeks are typically thinking about bleeding risk around delivery. A large meta-analysis covering nearly 374,000 women found that aspirin use during pregnancy was associated with a 20% relative increase in the odds of postpartum hemorrhage. That sounds significant, but the absolute risk remains low for most women. When only the highest-quality randomized trials were analyzed, the increase dropped to about 12%.
Stopping a few weeks before the due date gives the body time to restore normal platelet function. Aspirin irreversibly affects platelets, but your body makes new ones constantly. Within 7 to 10 days of your last dose, your clotting ability is essentially back to normal.
The Case for Continuing Until Delivery
Preeclampsia can develop late in pregnancy, including in the final weeks. Stopping aspirin at 36 weeks removes protection during a window when preeclampsia still poses a real threat. ACOG’s current position reflects this concern: for women at high risk, the benefit of continued protection outweighs the modest increase in bleeding risk.
One practical concern patients often raise is whether aspirin interferes with an epidural. Stanford Medicine’s anesthesia guidelines clarify that low-dose aspirin does not need to be stopped before neuraxial procedures like an epidural. You can continue your daily 81 mg dose and still safely receive regional anesthesia during labor.
Early Discontinuation in Select Cases
A 2023 randomized trial published in JAMA tested whether aspirin could be stopped even earlier, between 24 and 28 weeks, in women whose blood markers showed a low risk of preterm preeclampsia. The study found that early discontinuation was noninferior to continuing until 36 weeks, meaning outcomes were not worse. This approach relied on a specific blood test (measuring placental proteins) to identify women who could safely stop early.
This is not yet standard practice, and most clinics do not offer this blood test routinely. But it suggests that in the future, aspirin duration may become more personalized rather than one-size-fits-all.
What This Means for Your IVF Pregnancy
If you were prescribed aspirin only during your IVF cycle to support implantation, your clinic may have already told you to stop around the time of your positive pregnancy test or shortly after. If you’re unsure whether that instruction still applies now that you’re further along, it’s worth confirming with your OB, especially if you have risk factors for preeclampsia.
If you’re taking aspirin specifically for preeclampsia prevention, expect to stay on it well into the third trimester. Your provider will decide between a 36-week stop date and continuing through delivery based on your personal risk profile, your blood pressure trends, and whether you have additional complications. There is no universal “right” week to stop. The decision balances two real but manageable risks: late-onset preeclampsia on one side, and a small increase in postpartum bleeding on the other.
Do not stop aspirin on your own without discussing it with your care team. The timing matters, and your provider has context about your specific pregnancy that general guidelines cannot capture.