my daughter is having a baby she is 17 weeks pregnant she is 25 years old and had a blood test of spina bifida and downs syndrome, the downs came back positive. She has just come from the hospital where she has had an ultrasound done. the baby head was moving up and down the tech said that the skin looked thick when babys head was back but then ok when normal position. Does this sound like a downs baby and, if the baby is very active in the womb does this mean the baby is not downs. Thank you