Tri-previfem -- which is the generic form of Ortho Tri-Cyclen -- is an oral contraceptive which contains progestin and estrogen. Like most oral contraceptives, it can cause various side effects, the most common being weight gain.
Most oral contraceptives, including tri-previfem, slightly increase the production of testosterone -- the male sex hormone -- in a woman’s body. Elevated testosterone levels cause more muscle mass to develop and the extra muscle results in weight gain.
The estrogen and progestin in tri-previfem can cause fluid retention. Retaining more fluid will create the feeling of bloat and weight gain.
The hormones contained in tri-previfem and other birth control pills can cause some women to experience an increase in appetite. Accordingly, the size and frequency of meals may increase, leading to weight gain.