One breeding *can* result in pregnancy but not always. So you might not have a pregnant dog. Either way, get your male neutered as soon as possible so you don't have another accidental breeding. She's still in heat after all, so he could breed her again.

In case she is pregnant, write down the date of the breeding so you know when to expect puppies. Seek out the advice of a good vet and read as many resources as you can.

A vet can do a pregnancy test (like for people) but they can be unreliable. You can also do an ultrasound, but that can be expensive. One of the best things to do is to have a vet palpitate (feel for puppies). This is best done 26 - 32 days after the breeding.

Here are some signs to look for to help you determine if she is pregnant:
Week One (Day 1 - 7 from breeding)
+ Possible morning sickness (may stop eating or vomit)
+ Possible personality changes

Week Two (Days 8-14)
+ Possible morning sickness

Week Three (Days 15-21)
+ Possible morning sickness

Week Four (Days 22-28)
+ Possible clear vaginal discharge
+ Mammary development begins (she'll start to get milk)

Week Five (Days 29-35)
+ Swelling becomes noticeable
+ Loss of "tuck-up"
+ Weight will start to increase

Week Six (Days 36-42)
+ Nipples darken and enlarge
+ Abdomen continues to enlarge

Week Seven (Days 43-49)
+ Abdomen hair will start shedding
+ The female will start to look pregnant at this point

Week Eight (Days 50-57)
+ Fetal movement can be detected when female is at rest
+ Puppies can safely be born from now on
+ Milk may be squeezed from nipples
+ The female will be very large.

Week Nine (Days 58-65)
+ Nesting behavior may be seen
+ Female may become distressed (panting, pacing, acting uncomfortable)
+ Temperature should be around 100.2-100.8 degrees Farenheit
+ When temperature drops to around 98-99.4 degrees Farenheit,
puppies should be born within 24 hours
+ Appetite may disappear as whelping approaches