It will not hurt the baby but more of causing aches for you instead when you stay in the same position for too long. Try to take short break in between for some quick stretches. Tonnes of videos on YouTube to follow along for quick stretches.
Check whether your office has tables with adjustable height (something like Omidesk or those from IKEA). Stand-up meetings are in trend too.
My job is quite desk bound too. For me it's lots of pantry/toilet breaks and to include short walks nearby office for 5-10 mins.
Baby will not be harmed. Can try to take little breaks by standing and walking around the office or to the pantry.
Anonymous