From an obstetric point of view, it is not advisable to aim for a twin pregnancy if you are trying to conceive naturally as twins are considered high-risk pregnancies and can potentially be associated with complications for both the mother and fetuses.
Women with infertility issues who seek fertility treatments are at a higher risk of twin pregnancies should the treatments be successful though. These treatments include taking oral ovulation medication, superovulation intrauterine insemination (SOIUI), and in-vitro fertilization (IVF) because these fertility drugs usually result in the production of more than one egg.