Having posts birth deaths in my colony

Hi guys, I am having repeated Dam fatalities this winter in my colony. My girls are looking healthy and going full term with their pregnancies but sort after birth they are falling ill and dying. W are finding the dead Moms surrounded by babies. Any insight?

What are you feeding? What is the temperature? How well do you know this line of rats, do they have a history of birthing problems?

There's not enough info here to make a guess at what the problem could be.

This is the same line of rats that I have been breeding for 3 years every 8 months I will pick up a male to add different genes. The room temp is 70 gets a bit cooler in the winter sometimes if the outside temp dips to -10 or more. There have been no major changes to my setup except for the adding of additional racks. The rats are on Purinas Rat Chow, with some Puppy Chow and a seed mix occasionally. They are on gravity fed watering sytem.

I would start adding fruit and veggies into their diets. The pregnancy might be taking too much out of mama. After I know intercourse has occurred I start feeding the future mama cooked eggs, tuna, bigger nuts ( think Christmas nuts ), cooked pasta, and fruits/veggies. I don't do it everyday, but at least 3 days a week. Keep feeding them what you feed them now as well ( 1 bowl extras, 1 bowl regular food ). It's easy to do if you make yourself some food, make her some food too. Because of this I have exceptionally healthy rats. Beautiful coats, bright eyes, BIG litters, and I have not lost 1 baby or mama.

As for temp, I keep it at 74. Comfortable for both mom and babies!