How about using birch xylitol as a mouthwash?-I do this but would not
recommend consuming the xylitol.
Use grassfed butter to oil swish for 15 minutes in mouth then spit
out.
If you buy pasteurized butter get kerrygold butter(available in
stores) in addition to the butter oil for activator X.
eat shellfish 2x week at least
If your not in pain I wouldnt recommend filling them, I have a cavity
I wont be filling-tooth material is not replaceable and composite
fillings contain toxins like BPA and formaldehyde.

What kind of sugars do you eat? I've read maple syrup is better and
wont cause cavities due to the minerals. Honey promotes cavities.
Try eating only cooked fruit with fat or cutting out fruit/sugars for
a time.

I also recommend having a dentist check your teeth every few months
to see if they improve or get worse.
You could try applying uncle harrys bee propolis to your decayed
spots.
Eat more cheese
Eat as much nutrient dense foods as you can afford because you need
more than usual during pregnancy to supply fetus

2-4+ cups of raw grassfed milk daily (add 1 ounce of raw cream to
every 6 ounces of milk for regular whole milk, drink at room
temperature if possible).
2 cups daily of bone soup, made from slow cooking the bones & organs
of fish, chicken, beef and so on.
1-4 tablespoons of grassfed bone marrow. Either raw or cooked.
>>From-http://www.curetoothdecay.com/Tooth_Decay/foods_stop_decay.htm