Fascinating thread.
I have spina bifida occulta (benign spina bifida). There is nothing to see on my back but I had continence problems, and endless urinary tract infections, as a child and had an operation, when I was five, to lengthen my Achilles tendons as I was unable to put my feet flat on the floor.
I took my folic acid religiously when ttc DS1 so you can imagine my horror when he started walking and seemed unable to put his feet flat on the floor. The orthopaedic paediatrician I saw pretty much dismissed me as a neurotic first time Mum. His advice was that "if it bothers you" to put DS1 (@13 months, just walking) in "wellies a size too small" so that he could not walk on tiptoes. Needless to say I didn't follow his advice!
He told me there was no way DS1 had any form of S.B. and that his walking would correct itself. He added that if he was still doing it when he started school the teasing from his peers would stop him then, Nice man. When DS1 was four we moved to a different area and I asked to be referred again, as he was still walking on tiptoes. This time the orthopeadic paed. said that he had "extremely limited" movement in his hamstrings, and ankles - far more restricted than one would expect in a four year old. He said that he was fairly sure that DS1 DID have S.B.O. - but that it was milder than mine. DS1 has been having physiotherapy (and has special insoles to correct the position of his feet) ever since. He is also still in nappies at night, despite being dry in the day since he was 3 (now 6.5)
The really bad part - when the 2nd Orth. Paed. told me that the likelihood was that I had a child with S.B.O...I was 7 weeks pregnant with DS2, and should have been taking a mega-dose of folic acid since pre-conception. I took a higher dose for the next 6 weeks or so..but was really worried. When DS2 was born he had a forked bottom cleft which can be a sign of a spinal defect. The only advice I was given was to "wait and see"..thankfully, his walking is fine (and he can do that crouching down on the floor with his feet flat and his knees bent which DS1 could never do!)
I have since done a lot of reading on the web about spina bifida - and the advice I have read is that, even if you have only a mild form of the condition, you should take the highest dose of folic acid if you are TTC (boyandgirl, don't know if you are planning any more but I would take the higher dose if there's a next time). Personally, I would apply this to Mums who have had a child with a sacral dimple/forked bum - as far as I know there is no danger to mother/unborn child from taking a high dose of folic acid. Something you might want to consider too, zippy539, if you're planning another one. I have just found doctors to be lamentably uninformed about spina bifida/spina bifida occulta..for example, no-one I have asked has been able to tell me if my children are at increased risk of passing S.B.O. onto their children.
I wish I had been more assertive when I was first concerned about DS1 - luckily DS2 seems fine but I had months of worrying which I could have done without.