9 Week Old Not Staying Asleep

Her naps during the day will continue to get shorter in length, but remain frequent (every 1.5-2 hours). Also, you may notice that your daughter will wake more frequently for a while and then vacillate back to sleeping through the night - especially during growth spurts.

My two words of advice are distraction and co-sleeping. Distraction (lights, sound, movement) will help calm your baby. While swaddled - you can walk around with her, turn on music or turn on a video - distracting them from fussing is what will enable them to fall asleep. Co-sleeping allows you to respond to their needs quicker, such as hunger, losing a pacifier, needing to be rocked, before they wake themselves up or jarring them awake by placing them in a crib. Plus, you can help cuddle them back to sleep - can't do that when they are in a crib.

J.,
I would first rule out colic/gas(is she burping after each feeding?) or is see satisfied after nursing? She may be hungry still or have a gas bubble. I nursed both my boys and they both had colic symptoms around 3 months old. I used to do infant massage for them as well. I found a video on it that walks you through all the different areas and how to massage them. Good Luck!!

My instinct is to say to let her sleep where she will. My in-laws had to keep their son in his car seat for several weeks because that was the only place he would stay asleep. Another friend's kid couldn't do the crib - he hated the smell of it and had reflux that required being in the car seat as well.

I'm guessing at 9 weeks, there's probably a pseudo-growth spurt which may be changing her sleep/feeding needs, or she may be more aware of not being held.

Most people will criticize me, but our daughter slept next to me in bed for the first year (initially because she was a poor sleeper, and then when going through chemo, it was easier on me when she needed to be fed).

We learned the hard way that not all kids are good sleepers. Our son, at 3.5, is in bed with me EVERY night.

I had the same exact routine with my first as your doing with your daughter now for bedtime...and he used to pull the same stunt as your daughter. *waking up as soon as put down...or if sound asleep, as soon as he realized he wasnt on mom/dad anymore. its very strenuous to get out of this habit. luckily, she is still pretty young. here's what i suggest: put her down right before she is asleep. where her eyes are closed but she's not snoring. Than, put her down, and of course she'll fuss, but leave her in there for 2 minutes crying. It seems like forever, but she needs to get worn out anyways, so just look at it like your helping her get to sleeep faster. (i know, its hard). than pick her up, burp her cause she prolly swallowed air from hyperventalating., than put her down again ALMOST asleep, repeat. eventually she will go to sleep. the next night, do the same thing, but a little longer crying. now, the point is not to torture yourself adn your child, its this: she needs to develop the concept of going to sleep on her own. thats why you put her down when she is almost asleep, so she is already aware that she is alone. but, not making her feel abandoned. picking her up again reminds her she's loved and not abandoned. i promise it works. this also develops into a healthy habit later of just being able to put her directly into her bed when its an approximate time (say 9:30), instead of waiting till SHE is ready to go to sleep. It worked for me on both of my children. My oldest, is now 2, and he had the same thing going on as your daughter..after i did this for maybe a couple weeks, he would just sigh when i'd put him down and then stay asleep. ironically, eventually he would arch his back letting me know he wanted to be put down and he was ready for sleep. Now he plays, reads books, etc. adn then goes to sleep on his own. my now 12 week old actually insists at around 9:30 (our scheduled bed time) to go into his bed before he'll even take his bottle for bed. crazy to me, since my first had the same issues as yours. it is hard to listen to your baby cry, but your doing her a favor by teaching her its okay to sleep by herself. a couple weeks of stress for the family is well worth the years to come of easy bedtime routines. :) good luck in whatever way you choose!
in response to sleeping in your bed/carseat. this will NOT help your child learn how to put herself to sleep. this is creating ANOTHER issue you'll have to deal with. Once your daughter is allowed to sleep with you, she'll always know its an option and you're opening a whole new can of worms. 2nd-my 12 week old has terrible reflux. falling asleep in the car seat isnt the answer here. i do agree with her on the note to always go with your instincts. no matter what anyone puts on here, including myself, you'll manage and figure it out. a mom knows her child better than anyone, and every baby is different. :) your story just sounded so familiar to me, that i wanted to tell you ALL about what i did. (i wrote a novel, sorry).

I haven't read Healthy Sleep, but I have read On Becoming Babywise and highly recommend it. Had my kids sleeping through the night by 7-9 weeks.

My guess would be that she's getting too long of a nap in the afternoon. The book recommends a 3 hour cycle during the day of feeding, awake time and nap. If she's getting 4 hours in the afternoon, she may be confusing day and night.

Good luck!