Aspirin is not known to cause miscarriage. According to Rebecca Smith, a medical editor for The Daily Telegraph, it can actually help prevent some miscarriages and increase a woman's chance to carry the pregnancy to full term. Aspirin is also known to prevent stroke and heart attacks.
According to Smith, some miscarriages occur due to thick blood, and a daily aspirin can help prevent miscarriages in women with this condition. It's recommended that women get tested for it after a first miscarriage because aspirin can prevent any future miscarriages. It's important to remember that sometimes miscarriages happen for unknown reasons, and there isn't always a treatment to prevent them.