Congrats on the pregnancy, hope things are going smoothyly. I had amnios w.both my pregnancies (I'm T1 for 23yrs, have a 3yr old and 5 month old). For my first (my son) amnio was unplanned, I had what seemed like ruptured membranes (water broke) at 30 wks and at 34 weeks they were trying to decide if they should deliever early or try to keep him in. They said lung maturity had a lot to do w.making that decision. His lungs were surprisingly beyond where they hoped for (very developed) so I was induced (and ultimately had a c-section).
2nd baby (daughter) had a huge growth increase in mid-30s weeks and they wanted to schedule a section around week 38. I was told they would have to do an amnio if we were scheduling a c-section for even 1 day earlier than 38 weeks pregnant, which ended up happening. I was scheduled to have her 37 weeks, 5 days and therefore amnio scheduled for day before scheduled section.
As for the amnio itself, it hurts, but not horribly and not for long. I found the worst part to be how damn scary it was. "Okay, lay perfectly still while we stick this long, long needle into your very pregnant belly and try not to move while it's in there." Scary, but over fast.
NOW- the part you may not want to hear. She was born after the amnio, a day earlier than planned because it broke my water (BUT- I may have again been leaking slightly prior to amnio, I was having contractions for previous 2 weeks). But- that is not unheard of and they were not surprised. Apparently while the risks are much smaller than having an amnio at beginning of pregnancy (ie- not risk of miscarriage) there's a risk of it making you go into labor.
Sorry to not bear only good news- but that's the deal as I know it. Not fun, but I think pretty routine. Probably much better than having a baby with underdeveloped lungs! Take care and good luck, Rachel