The combination of breastfeeding hormones and waking up multiple times in a night can cause erratic temperatures and confusing cervical fluid. If you have already had your first period post-partum you should be able to gather enough data to recognize a pattern and anticipate ovulation. If you have not gotten your first period post-partum it may be more difficult to anticipate ovulation. It is suggested to start charting when you see increased signs of ovulation such as watery, stretchy, clear cervical fluid. However, you may see this increase in fertile fluid a few times before you actually ovulate.