The other night I found out my dwarf hamster was pregnant, I didn’t expect it as Pets at Home had?

Separate the male babies after 4 weeks. You should remove male pups after they are weaned (at age four weeks). They are sexually mature at this age, and you want to prevent inbreeding. Dwarf hamsters are more mild than other breeds, so you can leave the female pups in the cage with their mother.

My Hamster Had Babies! What Should I Do?"
Sometimes a hamster will have unknowingly been bred at the pet store or your pair of hamsters were incorrectly sexed and you may be surprised to find a litter of babies in your hamster's cage shortly after bringing them home. The most important piece of advice here is to not disturb the mother hamster. A hamster that has given birth should be disturbed as little as possible or she may become agitated and abandon, neglect, or even eat her babies.

This means other than providing food and water, you should leave your hamsters and their cage alone as much as possible for the first couple of weeks. While it is tempting to look at the babies and make sure everything is okay, it is best to leave the mom alone to do her thing.

Place strips of toilet paper or facial tissue in the cage so the mother hamster can build a soft nest. Ideally, you would do this once you realize your hamster is pregnant (it is usually pretty noticeable a couple of days before birth just by the sheer size of her abdomen).

Don't try to handle the babies at all for at least two weeks.

Once the babies have arrived don't worry about cleaning the cage for a while. Leave it alone for the first 10-14 days. You can spot clean really wet spots if absolutely necessary but avoid disturbing the nest. If you have just noticed your hamster is pregnant, do a thorough cleaning to prepare for the new arrivals.
Make sure to provide plenty of food and fresh water but make feeding and watering as efficient and calm as possible.
While it is okay to have a quick peek in the cage on occasional avoid sitting and watching the mother and her pups for long periods of time.
Keep in mind that the mom will be very protective so she may act more aggressive than usual towards you. This is natural and no cause for concern.
Though interference should be avoided if at all possible if for some rare reason you must move a baby, use a spoon so you do not get your scent on the baby (the mother may eat her young if you get your scent on the babies). It is rarely necessary to move a baby though even if they are out of the nest. The mom will usually retrieve any stray pups and return them to the nest.
Weaning the Baby Hamsters
The hamsters will be ready for weaning at about three weeks of age and it is best to separate the male pups into one group and the females into another. Syrian hamsters can stay in these male and female groups for another two to three weeks but then they must be separated so there is only one per cage (or else this pregnancy cycle will start again).

Separating the Father Hamster
If you ended up with a male and female dwarf hamster by mistake, it is best to remove the male as soon as possible after birth, with as little disturbance to the female as possible. While the male will not harm the babies and may help with rearing them, the female can get pregnant again shortly after giving birth and this can be very hard on her body.

Feeding the Mother Hamster
Make sure you are feeding a high-quality hamster diet with lots of protein.

In addition to a good quality diet, you can offer small amounts of hard-boiled egg, bits of cooked chicken, cheese, and wheatgerm to give the mom a nutritional boost.

Young Mother Hamsters
Unfortunately, if you got a pregnant hamster from the pet store she is probably quite young and may not have the best mothering abilities. She may be more likely to abandon or even cannibalize her babies. If she doesn't care for them and they are less than 10 days of age, it is extremely difficult to save the babies. It is best to make sure you get your hamster from a store that separates males from females at a young age to avoid surprises like this.