I BF (80%) and FF (20%) my 1st child up to 6 months before I gradually stop BF her.

She is now 22mths old. Though she looks strong, her immunity system seems quite low as she get sick every month and now has a cough with phelgm for nearly 2 month and on off running nose.

Now I just delivered my 2nd kid and start BF again. My current supply is more than my baby's demand.

Would giving my 1st kid some breast milk now still helps in building up in her immunity system? Or shall I just store up for my 2nd kid?

Hope someone can on this enquiry.

Many thanks.