Re: Back to work at 1 month?
Welcome to the forum!
Given that your baby is so ill right now, I can totally understand your worry about bringing her into contact with a bunch of germy little kids, with their snotty noses and grubby hands! However, as the mom of 2 kids I encourage you to do what you had originally planned and simply bring your baby with you.
First of all, she's little enough that you can wear her in a sling all the time, and that will minimize contact with the other kids and their germs.
Second, the immune systems depends on challenges from bacteria and viruses in order to develop normally. Exposing baby to the normal dirt and germs of the kids you nanny for will actually be good for her immune development. Remember, most of what your LO will come in contact with is going to be relatively harmless. I know it must be hard to believe that given that she's sick in the hospital right now! But the average cold or tummy bug is really nothing to worry about, even in a young baby. My second kid got a lot more illnesses than my first, because big sister was always dragging something home from preschool. But almost everything my second born got from my first born was no big deal, even at the earliest ages.
Third, it's easy to care for a nursing baby and older kids. You nurse the baby (hopefully in a sling) and use your free hand to help the other kids. It's very difficult to pump and care for older kids- there are going to be times when you will need to choose between maintaining your pumping schedule and doing the many, many things which older kids need. What are you going to do when you need 20 minutes to pump, but the 1 year old is monkeying with your pump tubes and the 3 year old is sitting on the potty, crying to be wiped, and the 7 year-old just got home from school and is hungry? This is how pumping moms end up stretching out the time between pump sessions, which can quickly lead to reduced supply. Supply = demand, and when a mom is not nursing directly she MUST pump in order to maintain supply, and she MUST keep to a rigorous schedule with her pumping. And as the caregiver for small children, you know how poorly schedules and children mix!
Fourth, while your sister's offer is amazingly generous, I am not sure how workable it's going to be. She has a supply that matches the needs of one 9 month old baby. 2 days a week she would need to match the needs of 2 babies. It's usually hard for a mom to develop a supply which is so robust and flexible that she can essentially nurse twins part-time. She would probably need to pump even during those days when you're not at work, in order to make sure she had enough milk for the days when she'd be caring for both kids. (Again, it's that supply = demand thing.)
Fifth, unless your sister lives in a bubble, her house and her baby aren't going to be germ-free. I know you probably feel more comfortable with her germs than with those of non-relatives, but I think your baby is likely to be exposed to plenty of germs even in your sister's care. You'd be giving up a lot for what is, IMHO, a very minimal gain.
ETA: If you do choose to pump, you will want to pump for 15-20 minutes every 2-3 hours during the time you are separated from your baby. You will want to use a high-quality pump with correctly sized shields. Since you'll be working just 2 days a week, an intermediate pump like an Ameda Purely Yours might be adequate for your needs. Pumped milk should be placed in the refrigerator during the workday, and then taken home and either stored in the freezer or used in a bottle ASAP. Pumped milk is good in the fridge for around a week, in an upright freezer for no more than 6 months, and in a deep freeze for as long as 12 months. Bags of stored milk should occasionally be thawed and taste/smell-tested for quality issues; some moms produce excess lipase which can impact the shelf-life of stored milk. Moms with lipase issues may need to scald their milk (an additional use of time you probably don't have!).
Re: Back to work at 1 month?
I would keep my baby with me, if I were you. No question. Mommal has a lot of good points. And my second kid gets a lot more sick than my first - even considering that my first has been at an in-home daycare with other kids since she was 4 months old. My second one had bronchiolitis at 8 weeks :( thanks to my first one sucking on the baby's fingers when she was sick. Every illness one of them gets - the other one gets. But it's ok - they are supposed to be building up their immune systems.
I'm sorry your baby is so sick, mama. That has to be so so scary to have such a little baby in the hospital. :hug
ETA: Could your sister watch those other three kids for the next month or so until you are ready to take them on again?