Generally, yes.

If you have a normal, low-risk pregnancy, commercial flights do not pose considerable risks, unless you're a flight attendant and has to fly really frequently, in which case you'd be exposing yourself to an unusually high level of cosmic radiation. For the regular holiday traveler, however, the exposure is not that high to be worried about. Generally, the second trimester is the safest time to travel by air. Unlike the first trimester, there is less risks of spontaneous abortion, and unlike the last trimester, there is less chances of premature labor.

Here are some tips from the MayoClinic for pregnant women who plan to fly:

• Ask for an aisle seat or a seat at the bulkhead - which offers the most space and comfort - or over the wings - which offers the smoothest ride.
• Fasten the safety belt under your abdomen across the tops of your thighs.
• Get up and walk every half-hour or, if the seat belt sign is on, flex and extend your ankles vigorously and frequently to prevent blood clots.
• Drink plenty of fluids. Low humidity in the cabin has a dehydrating effect.

Also, check your airline's policies regarding pregnant women. Some require a medical report from your doc, stating that you are fit to fly. Some of them might even refuse to take you in, particularly if you're on the latter stages of pregnancy, for fear that you'll deliver while on air.