The most common reasons for deciding to have a Caesarean include the baby's head being too large to pass through your pelvis, the baby being in a breech position or lying across your pelvis; placenta praevia (where the placenta has implanted near or over the cervix); and certain medical conditions such as diabetes or AIDS. It may also be necessary if you have previously had a Caesarean. This was once thought essential, because it was feared that the scar of the previous Caesarean section would open up during labor. But experience has shown that this does not happen with the horizontal ...