Baby Brezza data and heads' up!

TL;DR check your baby brezza formula concentrations, and make sure they're accurate or you may have sleep and growth issues

I'm gonna try to divide this out, because I'm unfortunately long-winded when I get excited (sorry).

EXECUTIVE SUMMARY:

We got a baby brezza formula pro 2 months ago and have had a great experience with the interface and multi-daily usage, but the machine setting was causing us to underfeed our LO, and seems to have been causing our sleep and growth issues. Pediatrician told us to toss the machine as she's heard this story a few times. YMMV there... But I think people should just check their machines and make sure it's doing what it should be.

THE STORY:

My LO is 9 weeks, and EFF for the past 5 weeks or so, mostly using the baby brezza formula pro. When we bought it, I performed the calibration test with our formula per their instructions on their website, and concluded that our "ideal" setting was between a 4 and a 5, with their website recommending a 4. So 4 it is! (note: in this testing, I was not measuring the water dispensed, as it was landing very close to the lines on our bottles, so I assumed it was accurate enough... This was a mistake).

Our LO slept MAX 4-hour stretches through the first 8 weeks, and plateau'd at that point, consistently waking up with wet diapers and crazy hunger. All in all... pretty normal for a newborn so we just kept at it. Her feeding quantities were really really good, with some bottles cresting 150ml at her 9.5 lb weight (and 8 bottles per day... routinely 27-31 ounces per day). All should have been really great, but her weight gain hasn't been keeping pace. She dropped from the 44th percentile to the 20th percentile between her 1-month and 2-month appointments, and our Pediatrician is pretty concerned because the numbers just don't add up. How is our LO eating so much but not gaining commensurate weight?

Queue an email from babybrezza to change the machine setting from 4 to 5 for enfamil neuropro gentlease (technically this happened 2 days before the 2-month appointment, for those wondering why I was still using it at this point. I had made the change, but didn't realize the growth impact until the appointment).

I changed it at 6AM in the morning, and THAT NIGHT we had our first 7-hour sleep. Followed by 8-hour sleeps every night since over the past week and a half. after months of AT BEST 4-hour sleep stretches, we finally had some progress. She's slightly more stopped up (fewer, fuller diapers), but suddenly far less ravenous, and not cluster feeding. Hopefully her growth rate recovers, although she's a perfectly happy baby and my spouse and I are 25th percentile humans... so I won't worry too much about it as long as she's happy and healthy.

THE DATA:

In the initial calibration run, per the website I only measured the formula powder dispensed, and only at bottle sizes 2 and 3. My conclusion then was that a setting 4 was slightly dilute (about 7% low on powder mass) while a setting 5 was slightly too concentrated (about 5% high). The website recommended setting 4, and I assumed dehydration was a greater concern than a slight calorie deficit, so we went with the manufacturer recommendation.

In the most recent run however, I tested up to size 4 (our typical size made) and I also collected and weighed the water dispensed for each run. I found that a "4 oz" bottle dispensed was actually 116.6g+/-0.5g of water on average, so ~3.2g higher than a perfect 4 ounces. At setting 5, across 3 runs I measured 17.4g average formula powder, which means that a size 4 bottle at setting 5 is still about 3% more diluted than it should be. A setting 4 at bottle size "4 oz" when correcting for water dispensed, is around 15-20% too dilute, and overall has a higher variance between bottles because the powder dispensed varies more at those lower quantities.

Conclusion:

Based upon this, either as a product of manufacturer changes in the formula, or when my spouse and I increased our bottle size as our baby's feedings grew, the Baby Brezza became very inaccurate. Upon fixing it, our LO started sleeping longer stretches, and will (hopefully) have better weight gain.

For those using these machines, I strongly urge parents to check and maintain their machines AT ACCURATE BOTTLE SIZES to make sure they're as accurate as possible.

EDIT:

one point on this: comparing the baby brezza machine to scooping shows that it's far more accurate than scooping out formula, but the issue is variability. If someone is scooping formula, you can expect half of bottles might be 10% too high of concentration due to mounded scoops, and half are 10% low because of voids, but overall on average, you're probably pretty doing pretty well. With a machine calibration, an improper setting means you're inducing a CONSISTENT offset. It's like always feeding your LO 20% low, rather than sometimes feeding them low and somes high.