I would recommend : That you ask your OBGYN, or if you have already established a pediatrician, ask how long should you breastfeed. Most will say you should exclusively breastfeed your newborn until they are at least six months old.
Keep in mind: The longer you breastfeed your baby the more you will be passing on your protective antibodies. Your antibodies will help to protect your baby from infection caused by the flu.
Breastfeeding is just as rewarding to your baby as it is to you. Did you know breastfeeding can decrease the risk to breast and ovarian cancers. Now keep in mind lower risk does not mean no risk.
Happy Baby, Happy Mommy!
For more information you may find this resource useful: www.cdc.gov/breastfeeding