According to The Daily Puppy, the gestation period for Labrador Retrievers is 63 days. Canines typically give birth between 58 and 68 days after conception.
During the gestational period, dogs go through both physical and psychological changes. According to the Claws and Paws Veterinary Hospital, dogs start gaining weight around the fifth week of pregnancy. Development of mammary glands can start as early as 35 days but may not be significant until around 45 days. During the last month of pregnancy, female Labradors start preparing for birth and often undergo behavioral changes right before the birth process begins. Many female dogs become restless and irritable right before labor.