there's a long bridge between the placenta and baby.could climb up that bridge and increase the risk for infections. >> we contacted the american congress of on stay trigses. the group has no stance on the issue. their british counterparts say no research exists and there's no medical evidence that it is of any benefit to the baby. new reasons for excitement tonight at the national zoo, or maybe not. scientists say that the panda hormone levels are rising and that may mean she could be pregnant. pandas have a tendency toward false pregnancies. if she is, she would give birth in 40 to 50 days. >> that would be nice. back in china now. >> yeah. but you know, we have been down this path before. we have to be cautiously optimistic. we get excited and we find out she's not pregnant. >> that's true. maybe something is in the air. >> pollen is in the air. i have an allergy update. with all the cherry blossoms, most of our pollen content, cherry blossoms. >> oh yeah. a lot of people can't go down there. >> april fools, just kidding. >> haha. >>