Though your female hamster will gain weight once she is pregnant, weight gain alone does not indicate pregnancy. Other indications of pregnancy include nest-building, possible hoarding of food, and signs of aggression as her gestation period progresses. Hamsters reach sexual maturity quickly in life, with some hamsters capable of breeding as early as four weeks old. However, it is generally recommended that breeders refrain from pairing hamsters for mating until five to six months of age.  The gestation period for hamsters varies widely by breed. Syrian hamsters typically gestate for 16 days, while many dwarf breeds gestate for 18-21 days. Roborovski hamsters may gestate for up to 30 days.  Females capable of reproduction will want to mate every four days.  A couple days before your hamster is going to give birth, her stomach will swell to a very large size. However, this may also be an indication of a more serious condition. Swollen abdomens may indicate the presence of a tumor, impending heart failure, liver cysts, or in rare cases Cushing's Disease. If your hamster's belly is swollen, it's best to have her examined by a veterinarian to determine whether it's pregnancy weight or something more serious. It's important that your hamster delivers her babies into a clean environment. In order to ensure that this happens, clean your hamster cage two weeks after your hamster gets pregnant (or when you determine that your hamster is pregnant), and add additional fresh bedding.  Know that, since the mother hamster will not like being disturbed as it gets closer to her delivery date, you may not be able to clean the cage later in her gestation period. Cleaning the cage within 2 - 3 days of her "due date" can unsettle a female hamster sufficiently that she rejects the babies when they are born. Cleaning the cage as soon as possible after determining that she is pregnant may be your best option. After cleaning the cage during the gestation period, do not clean the cage again until 14 days after the birth. Pregnant...

TL;DR in Indonesian:
Ketahuiapakah hamster Anda sedang hamil Pahami daur hidup hamster. Bersihkan kandang hamster Anda Gantilah jenis makanan hamster Anda. Ambil roda hamster dan mainan-mainan lain dari kandang hamster Anda. Pisahkan ayah hamster dari kandangnya jika Anda belum melakukannya. Sediakan bahan pembuat sarang yang halus untuk hamster Anda. Siapkan tempat tinggal untuk bayi-bayi hamster. Ketahuilah perkiraan waktu yang dibutuhkan saat proses melahirkan.