Apparently the tannins in the teas block absorption of some nutrients including folic acid.
This is a short term effect, so would only block the absorption of the folic acid in the food that was eaten at the same time the tea was drunk. A single cup of green tea that is drunk in between meals should not cause any significant problems, especially if the prenatal vitamin is taken at a different time of the day. At 16 weeks, it is possible to have the quad or triple screen done or just the AFP level depending upon your lab and medical provider. These tests can determine whether your baby is at high risk for a neural tube defect (spina bifida). You will probably also have an ultrasound done soon and that can definitively rule out spina bifida if the baby is in proper position at the time of the scan. Unless you have a strong family history of spina bifida, you shouldn't be overly concerned. Also, the neural tube forms within the first 28 days of the pregnancy, so there would be no reason to stop drinking the tea at this point. Just don't take your vitamin with it!
i didnt know that it blocked folic acid.. i have a folic acid deficiancy and i am suposed to take 1 miligram of folic acid a day plus baby asprin..
i was told that drinking any tea while pregnant is very bad.. i was told that it works as an uterus stimulate thus it stimulates your uterus..
i know nothing about spinal bifida.. i would try asking your obgyn and thn i would get a 2nd opinion as well