If you've recently had a baby and are breast-feeding, you're probably aware that your periods stop during this time. The clinical term for this absence of periods is amenorrhea. If you're not menstruating, you're most likely not ovulating, and if you're not ovulating, you can't become pregnant. You don't have a period while you're breast-feeding because you have increased levels of the hormone prolactin, which suppresses the hormones that trigger ovulation. You shouldn't assume that just because you're breast-feeding you're not fertile. Your first period after birth will generally be preceded by ovulation 14 days earlier. That means you can become pregnant before your first period. If you want to become pregnant while your experiencing amenorrhea due to breast-feeding, there are some methods you can try. You'll have to reduce the amount of prolactin in your body. This might mean altering exclusive on-demand feedings. You'll also need to monitor your basal temperature as well as cervical fluid and position.