Is it possible to regain your green card if you lose it for being out of the country?

A green card holder who remains outside the U.S. for a continuous 365 day period loses his/her status as a matter of law. It it is unavoidable and you lose your status, your husband can re-file another petition for you to get a new green card.

If your green card will get revoked for abandonment of U.S. residency, you could receive a new one by going through the entire process (immigrant petition, interview, etc.) once again. You might be able to convince USCIS not to revoke your green card by showing that you always intended to return to your U.S. residence at some future date. Maintaining accounts in U.S. banks and with retailers, keeping memberships and subscriptions, having a place to live available (if not, keeping furniture and household items in storage), maintaining a current driver's license, etc. - all of it usually helps. Make sure to preserve a letter of your doctor stating that you should not travel now, and have it with you (with a certified translation if it is in any language other than English) when you travel to the U.S. Under the circumstances, I would say the chances are fairly good that you will be let into the country without too much ado. However, there are no guarantees. You might also apply for an advance parole. Use Form I-131 (the form, instructions, and the link for on-line filing are at uscis.gov/forms). If approved, this document would give you up to 2 years outside of the U.S. without the risk of losing your green card.

Yes. If you lose your permanent residency status due to abandonment, you can regain it by starting the I-130 petition process again. However, you should explain to the CBP officer at the port of entry that you were absent from the US for an extended time because your doctor advised you not to travel until your medical condition improved.

Have you applied for a travel document? If not, you should. It is valid for two years and it allows you to preserve your permanent resident status without actually coming to the U.S. for this two-year period. Of course, the difficulty is that you have to be fingerprinted for this permit, but it could be possible in the nearest US embassy or consulate. Other than that, preserve your documents of your pregnancy and your doctors written advice not to travel. I also assume that you have connections with the US - a home or some other ties, so that it does not look like you are using your green card as a travel visa to come and visit the US? If you do not actually live in the US or if you do not have any plans to return, you may ultimately lose your green card. If that happens, your husband will have to start the whole filing process all over again. There is no reason why you would be denied a green card a second time, but the point is that it is another filing process, more fees, etc. - just like it was when you first filed (but maybe even more expensive now).