Gestation, or the term of a pregnancy in dogs starts from the first time they are bred, or fertilised, and lasts until the puppies are born. This period can vary based on the breed or size of the dog, but usually is about 9 weeks. Unlike humans, female dogs can have menstruation cycles throughout their entire lives, and can have puppies at any age after their first heat.

Puberty begins in a female dog from between 6 to 24 months of age. She mates when she is in heat, or oestrus. There are four stages of the oestrus cycle:

*Proestrus Stage: This is the preheat period, lasting 4 to 9 days.

*Oestrus Stage: This is the stage when the female dog will mate, and lasts 4 to 13 days.

*Diestrus Stage: Lasting 2-3 months, this stage involves the pregnancy, elevated progesterone levels, and swelling of the mammary glands.

*Anestrus Stage: This is the longest lasting stage, about 5 months, when the female dog starts to prepare for the subsequent heat cycle.

It is usually hard to predict if your dog is pregnant or not, even if conception was 5 weeks prior. There is not a standard pregnancy test for a dog's urine or blood that can be done at home. It's generally advised to take your dog to the vet to confirm a pregnancy. A pregnancy is usually detected by X-ray 45 days or so after fertilisation.