Don't feel "terrible" at all! Not only have you been with this company for 12 years, your family life is more important than any company. I accepted a new job knowing I was pregnant (miscarried that one, sadly) then ended up taking a 12 week maternity leave right after 12 months with them.
Do not let misplaced "company loyalty" affect you and your husband's personal decision. I now work in the Outplacement business (counseling people who have been laid-off by companies). Companies don't hesitate to let people go as soon as their financials don't look as good as they want them to. It doesn't matter how long a person's been there, how hard they have worked, how old they are, or if they are pregnant, blind, or disabled - they show up in my office for help finding a new job.
Also, I had my daughter, my first and only, when I was 41. She is perfect, and it is a perfect time of life to be a parent!