Hamsters are often incorrectly sexed by pet shops or separated by sex too late to avoid pregnancy. Siblings and other relations can and will breed together. Hamsters do not always show signs of pregnancy until the very last few days of their gestation. It is vital to separate out the male if you have an unexpected litter, as otherwise they can mate within hours of giving birth.
Do ask for help from an ethical rescue or breeder, as they can support you.
Hamster mums are high-risk for cannibalising their litters, so it is vital to leave the pups and mum alone. Do not clean out the cage for the first 14 days, you can carefully spot-clean wet areas if they are a risk but do not touch the nest. Make sure that mum has clean bedding material available for her nest and is kept undisturbed.
Your hamster will need extra protein whilst she is feeding, small amounts of hard-boiled egg, bits of cooked chicken and cheese can be good additions.
Remove any items from the cage that could be dangerous for a wandering pup or mum, such as moving a water bowl to a platform where mum can access it but pups cannot fall in. It is a good idea to remove the wheel during pregnancy and litter-raising.
If you must move a pup due to it being at risk, then do so using a spoon to avoid getting your scent on the baby. You can warm this up in a towel before doing so to avoid chill. Most hamster mums will gather up any pups that have strayed from the nest, so you shouldn't need to intervene in this case. Sadly, if a pup has been moved out the nest by mum - this is often a sign that she knows something is wrong and this one will not survive. Many litters have a noticably smaller pup, known as the 'runt'. Runts can survive and live full lives, but they are higher risk than the others.
Keep food and water changes calm and quiet to avoid stressing out mum. Do not handle or disturb mum during this time, even a calm and friendly pet will be protective of her young and she may charge towards your hand or be aggressive towards you.
Make sure you have checked the litter maturity rates of your species of hamster and separate them at the right age to prevent breeding.