How? Is this something your OB/MW has told you or is it something you've deduced based on kicks? If the latter, how?
Because, for the life of me, I can't tell. I feel like I've got Vishnu in there, for all the bizarre places I get poked and prodded.

Re: those who know what position the baby's in...
I wouldn't have known except we had a 3d u/s and they told us she was head down already (also where her stomach and butt were), which my OB confirmed at the next appt.
Even still though, I get lumps in the oddest places and can't fathom what body part she is smushing against my uterus...
I figured it out and then had it confirmed with an a few days later. And since then, I've been able to correlate his movements with what I see on the ultrasounds for future reference.
What gave it away at first for me was the poking sensation I was getting on my bladder/lower uterus area. I knew it had to be a small appendage creating that sensation. The other thing that confirmed it for me was the small, long appendage pushing out where my ribs used to come together. I was associating that with a foot.
I was right on both accounts. He's head down and stretches his arms out sometimes, catching my bladder area with his tiny hands. And he's got tons of leg crammed in my upper ab area with feet that like to stick out when he's trying to get comfortable.
My MW told me she was head down. I had no idea prior to that. LO's back/butt is on the left side of my belly and her feet are to the right. She often kicks her heels out to stretch which is strange.
edit: i can also tell because my belly looks low & the pressure is ridiculous.
I couldn't tell either, but I had a u/s last week and they told me then.
I think the doctor can tell just from examining you, but I haven't been asking at every appointment, so I didn't know until last week.
I have no idea what is poking me or where LO is at all. I often feel hard things that feel like his head all over the place, but at 31 weeks, the dr said it's unlikely he has truly settled in to being head down all the time. So I just go with the idea that he's probably still moving all around! I can't believe that some people know what they're feeling! I'm jealous!
With DD I had no idea she was transverse until I kept "measuring small" and my OB sent me for an u/s around 32 weeks. Then at 35 weeks she was head down. I never knew when she actually turned to head-down, though.
This baby I suspected was transverse because EVERY TIME I lay on my right side, I feel these LITTLE nubbins (so I knew it was fingers or toes), and EVERY time I lay on my left side I feel something round and huge (head or butt). At 32 weeks, though, my OB did an u/s and baby was head-down and "sunny side up." I have no clue what position LO is in now, there is still SO much movement going on! My OB said if there was any concern they could check again by u/s at 36 weeks.
At my anatomy scan he was breech.
Since then, I figured he was head down, but on a diagonal b/c I get bony foot & leg-like protrusions far on my right side. I can trace it with my fingers & certainly looks & feels like a leg. Then when I get lumpy toward the same side, I figure it's his butt. When I get lumpy on the other side, I figure it's his shoulder.I also feel hiccups pretty low.
Last month, I asked the OB if she could tell his position & I described what I was feeling & she confirmed at least that his head is down left where I thought it was.
He's still in the same position as far as I can tell. I do not get kicks high up in my ribs. I do get the suffocating feeling daily though, when something is pressing up on my diaphragm.
I keep telling him to straighten out!
I assumed he was head down because my belly was lopsided and his kicks were always high up on my belly.
My OB confirmed that he's head down and has been for the last several appointments.
I'm having frequent scans, so that helps.
And my MW is telling me now, palpating (?) at my appointments.
After my one scan told me she was head down and feet to where I'd been feeling the most kicks, now I know when I have that sensation again, she's head down. Likewise, I can tell if she's breech (rare) because I feel like lots of little steps on my lady bits.
The hospital did a quick ultrasound over the weekend and told me LO is head down, but otherwise I wouldn't have known that for sure. About a month ago LO was kicking me in the crotch something awful, but the kicking has since become regular on the left side, so s/he is apparently better-positioned now.
There is a very hard lump at the top of my uterus. Also when I went to my doctors appointment last week I had an internal exam and she could feel Gabrielle's bum through my pelvic floor.
at my last ob appt she felt around my stomach and said babys head is down and i know this from 20 yrs experience. lol so...im not sure how correct she is but ill take her word for it.
eta: also, all the hiccups i feel have been lower down between my pubic bone and belly button.