A typical cat pregnancy will last 63 to 69 days, depending on the accuracy of the human's calculations of actual impregnation. Before becoming an animal rescue facility, we owned a cattery with registered Siamese varieties. Our queens almost always birthed on the 63rd day. If a pregnant cat goes beyond 65 days - I'd schedule a vet visit. We also made at least three vet visits during the pregnancy to monitor health (of queen and kittens), and to know when delivery would be likely. This is of utmost help.
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A cat is usually more than half-way through the pregnancy before showing signs or symptoms of pregnancy. Depending on the overall body shape and weight of the queen (pregnant female feline), you may not be able to really tell she's pregnant until just a couple weeks before delivery.
An experienced vet can palpate a female around 3 weeks or so along and determine pregnancy, or perform a CT Scan, Ultrasound or even X-ray, depending on circumstances and timing. This is highly recommended in order to best know that it's a healthy pregnancy and that both mother and kittens have the best chance for survival.
Good luck and best wishes
Own Animal Care org.
Animal Rescue&Care Org Owner; Animal Care author; Animal Behavior Consults.;Cert. Avian Specialist;