Medical professionals, including the American College of Obstetricians and Gynecologists (ACOG), strongly advise avoiding roller coasters during all stages of pregnancy, including the first trimester. While the "bump" isn't visible yet, the risk isn't about physical impact on the stomach—it's about rapid acceleration, deceleration, and jarring G-forces. These forces can cause placental abruption, a condition where the placenta prematurely peels away from the uterine wall, which is a life-threatening emergency for the fetus. A supportive peer "safety first" reminder: even if your friend "rode one and was fine," the risk of "shearing forces" on the delicate internal attachments is too high. Most theme parks, including Disney and Universal, explicitly post "No Pregnancy" warnings on high-intensity rides. In 2026, it's best to stick to the "Gentle" attractions like boat rides or carousels to ensure a healthy pregnancy.