Breastfeeding, perimenopause (the time leading up to menopause) and the first few years following menarche (the onset of menstruation during puberty) are considered the most challenging times to practice Fertility Awareness (FA). Fertility Awareness can be used to effectively prevent pregnancy during these transitional times, but the “rules” for preventing pregnancy during these times are somewhat different than the standard rules, and there are additional things to understand, such as how nursing & parenting behaviors can influence how soon fertility returns after birth. When cycles are irregular or absent, whether due to puberty, lactation, or perimenopause, experienced FA instruction can be invaluable.