Medical professionals and theme parks in 2026 strongly advise against riding roller coasters at any stage of pregnancy, including at four months. While the fetus is somewhat protected by amniotic fluid, the intense G-forces, rapid acceleration, and sudden jarring movements of a coaster can lead to placental abruption—a serious condition where the placenta separates from the uterine wall, cutting off the baby's oxygen supply. At four months (the second trimester), the uterus has grown out of the protective pelvic cradle, making it more vulnerable to the restrictive lap bars and harnesses designed for non-pregnant bodies. Additionally, the hormonal changes in 2026 pregnancies can increase joint laxity, making the physical strain of high-speed maneuvers more likely to cause maternal injury. It is always safer to stick to gentle, slow-moving attractions like boat rides or carousels that do not feature "expectant mother" warning signs.