First trimester · Days 0–7

Week 1 of dog pregnancy: fertilization and first cell divisions

Eggs are fertilized in the oviducts and the embryos begin to divide. Nothing is visible and she acts normally.

Updated October 2026 · Information only, not veterinary advice

What you may notice

Keep her on her usual adult food and routine. Do not add supplements, and ask your vet before any vaccine, flea treatment or dewormer.

Keep her usual adult food and portions. Do not add supplements.

No visit needed yet. If you are planning ahead, book the day-25 to day-30 ultrasound now.

Questions

Can you tell a dog is pregnant in week 1?

No. There are no reliable signs this early, and a scan cannot detect pregnancy yet. The earliest confirmation is an ultrasound at about day 25 to 30.

Is normal exercise safe in week 1?

Yes. Regular walks and play are fine. Avoid anything unusually strenuous or risky.

Keep reading

Enter a date and see her current day, week and what to expect now.

Day-by-day dates for vet visits, X-ray, setup and temperature checks.

What happens, what to feed and when to see the vet, weeks 1 to 9.