Pregnant women should take special precautions when flying, according to the Bonn-based National Association for Health Information and Consumer Protection (BGV).
As there is a heightened risk of thrombosis during pregnancy, it said, expectant mothers require sufficient legroom and should wear compression stockings to prevent blood clots from forming in their legs.
The BGV also advises them to stand up repeatedly, walk around the aircraft, and do leg exercises if possible.
Women in the first trimester should avoid long flights because cosmic radiation could damage the brain of the fetus during that stage of development, the BVG said.
Airlines generally refuse to transport expectant mothers from the 35th week of pregnancy on. Beginning with the 28th week, airlines sometimes require a certificate stating that childbirth is not imminent.