What is the effect of Acetylsalicylic acid (Aspirin) on conception?

From the Guidelines

Aspirin is not recommended for routine use when trying to conceive, as it may interfere with implantation and cause side effects, and its benefits on conception are not established. When considering the use of Acetylsalicylic acid (Aspirin) in the context of conception, it's essential to weigh the potential benefits against the risks. The provided evidence primarily focuses on the use of low-dose aspirin for the prevention of preeclampsia in pregnant women, rather than its effects on conception itself 1. Key points to consider include:

• The USPSTF found that low-dose aspirin reduces the risk of preeclampsia by 24%, preterm birth by 14%, and intrauterine growth restriction (IUGR) by 20% in clinical trials 1.
• However, this evidence does not directly address the effect of aspirin on conception.
• Aspirin can affect blood clotting, which may interfere with implantation in some cases.
• Potential side effects of aspirin include stomach irritation and bleeding. Given the lack of direct evidence on the impact of aspirin on conception and the potential for adverse effects, the safest approach is to avoid aspirin unless specifically prescribed by a healthcare provider for a medical condition. For individuals trying to conceive, focusing on proven fertility-enhancing strategies such as tracking ovulation, maintaining a healthy weight, avoiding smoking and excessive alcohol, and seeking timely fertility evaluation if needed is recommended. Always consult with a healthcare provider before taking any medication, including over-the-counter drugs like aspirin, when trying to conceive or during pregnancy.

From the FDA Drug Label

If pregnant or breast-feeding ask a health professional before use. it is especially important to use aspirin during the last 3 months of pregnancy unless definitely directed to do so by a doctor because it my cause problems in the unborn child or complications during delivery. The FDA drug label does not answer the question.

From the Research

Effect of Acetylsalicylic Acid (Aspirin) on Conception

• The use of aspirin in pregnancy has been studied for its potential to improve reproductive outcomes, particularly in women with antiphospholipid antibodies and a history of recurrent loss 2.
• Aspirin has both positive and negative effects on reproduction, as it can interfere with implantation but also support the maintenance of pregnancy 2.
• Low-dose aspirin has been shown to have a positive effect on reproductive outcomes, particularly when used in combination with heparin 3.

Aspirin and Pregnancy Outcomes

• The use of aspirin alone has been shown to have a limited effect on live birth rates compared to placebo, with a risk ratio of 0.94 (95% CI 0.71 to 1.25) 3.
• However, the combination of heparin and aspirin has been shown to increase live birth rates, with a risk ratio of 1.27 (95% CI 1.09 to 1.49) 3.
• Aspirin use has also been associated with a reduced risk of pregnancy loss, with a risk ratio of 0.48 (95% CI 0.32 to 0.71) 3.

Risks Associated with Aspirin Use in Pregnancy

• Aspirin use has been associated with an increased risk of bleeding in both the mother and the fetus 2, 4.
• Fetal intracranial hemorrhage has been reported in cases where the mother took low-dose aspirin during pregnancy 4.
• Placental abruption and antepartum hemorrhage have also been reported as potential risks associated with aspirin use in pregnancy 5.

Optimal Dosing and Timing of Aspirin Use

• The optimal dose and timing of aspirin use in pregnancy are still being studied, but recent evidence suggests that doses greater than 81mg may be associated with a higher reduction in preterm preeclampsia 6.
• Initiating aspirin treatment prior to 16 weeks of gestation may also be beneficial in reducing the risk of preeclampsia and other adverse perinatal outcomes 5, 6.