Breastfeeding, Expressing and work..

Why can't you express at work? 9 hours will leave you very engorged. If you do it quickly you could be at risk if mastitis and if the days are consecutive it may well affect your supply. Is there no way you can get 20 minutes to express?

Also, does your baby take a bottle now?

There are laws in place to protect breastfeeding for working mums. Your employer is obliged to allow you a break to express and somewhere private to do so.

I know this might seem completely impractical but if you want to maintain your supply for that feed and not risk engorgement, discomfort and mastitis, you are going to need to express!

You risk mastitis if you go 9 hours without expressing. You will likely also affect your supply.
The previous poster is right, your employer has a particular health and safety responsibility to you as a Breastfeeding mother. It's their responsibility to ensure you get time to have sufficient breaks for expressing and rest. If you get mastitis, you'll be off sick, so it's in their interests as well.

This page has a lot of useful information:

https://www.maternityaction.org.uk/advice-2/mums-dads-scenarios/6-breastfeeding-rights/continuing-to-breastfeed-when-you-return-to-work/

How many feeds are you doing across that 8/9 hr period? Personally I'd be replacing them with a bottle(s). You'll either get mastitis or screw up your supply otherwise. On the days you're around you can always still offer a comfort breastfeed on top of that bottle(s).