Is pregnancy a pre existing condition when enrolling in a group insurance plan?

NO! If you are having any trouble with group insurance and a pregnancy not being covered, contact your insurance commissioner's office IMMEDIATELY! Here's the deal: Under HIPAA (Health Insurance Portability & Accountability Act of 1996) GROUP insurance plans CANNOT by law consider pregnancy pre-existing. For example, if your husband is working at a job for several years, and has never added you to their group insurance plan and then you find out you are pregnant, the plan MUST allow you to be covered during their open enrollment. If they do not, CALL THE INSURANCE COMMISSIONER!

REFERENCE:

"Moreover, under HIPAA, preexisting condition exclusions cannot be applied to pregnancy, regardless of whether the woman had previous health coverage."

from http://www.dol.gov/ebsa/faqs/faq_consumer_hipaa.html

However, if you are on an individual health plan, this is all out the window. Be prepared for the insurance company to fight like mad if you've bought the plan within the last 12 months, they will attempt to get out of covering everything. Don't be afraid to contact your insurance commissioner and file complaints, it will lead to you getting what you deserve via the law, you are protected by it, so take advantage!