For the first six months, if your baby drinks mother milk only and you don't have your period, then the possibility of being pregnant is still low. But doctors will still advise you to take actions to avoid pregnancy. When your baby starts eating solid food and your period is back, then the possibility of getting pregant is quite high. For some moms who don't have their period back even after feeding their babies for 18 months, if they want to get preganat again, they may need to reduce their milk supply. Hope this information helps.