A standard language variety is a variety that's recognized as more correct* and acceptable than other varieties. Standard varieties have the following prototypical properties, though not all of these properties will be shown by all standard varieties, and non-standard varieties may nevertheless have some of them:
All airlines make up their own rules and regulations regarding pregnant women. Some do not restrict travel at all, no matter what stage of pregnancy a women is in, and others start to restrict at 7 months, although the majority restrict around 36 weeks.
If you are enjoying a healthy pregnancy, plane travel is likely to be safe. The second trimester is probably the best time to fly. You're likely to be over morning sickness. Later, your expanding belly could make airport maneuvers more challenging. Before booking, however, visit your doctor and describe the trip details. If your doctor clears you for flying, take some precautions before and during your flight to stay safe and healthy.