Where does the "have to" weight gain come from in the last trimester?

[DeChRi]

Just curious.

I know that through the first and second trimester there is a large blood volume increase, etc, etc. In the last trimester, besides the Ice Cream weight we gain, where does the weight come from that is "necessity" weight? I know that baby gains from about 2lb to birth weight (I have close to 9lb babies, so I expect another 7lbs of baby weight gain at least). I am just curious where else the final trimester weight comes from. With my last two I gained about 10lb from 28-26 weeks, then lost about 2-3lbs in the last month. I know it all varies, but what is the technical answer?

[dachshundqueen]

I dunno, but from my experience it's when babe puts on its fat stores. I also put on a whole lot of weight there at the end, but it was admittedly from guzzling coca cola like it was going out of style (my babes are generally soy, gluten, and dairy intolerant - so I knew to get it out of my system).

I had a 36 weeker that was skin and bones, we called her "stick baby". She came home at 5#5oz (was 5#12oz at delivery).

I had a 41+3 (actually 9 months from date of conception by my charting) that was a touch over 8 pounds.

Liz

[MyZymurgy]

I haven't seen this broken down for the third trimester only, but this is a breakdown for the entire pregnancy (assuming a 29 lb weight gain).

Where does it all go?
Approximate breakdown of a weight gain of 29 pounds
Blood 3 pounds
Breasts 2 pounds
Womb 2 pounds
Baby 7.5 pounds
Placenta 1.5 pounds
Amniotic fluid 2 pounds
Fat, protein & other nutrients 7 pounds
Retained water 4 pounds

Source: https://www.marchofdimes.com/pnhec/159_153.asp

I know last time I gained most the weight in the third trimester, but the majority of that was due to swelling and was lost within a week of delivery.

[RedOakMomma]

There is some science behind the water retention, though I can't remember what it is at the moment. I think it was covered in Ina May's Childbirth book, maybe? Wish I could remember. It made a lot of sense, though, and when I read it in my last pregnancy I thought "wow...that makes sense!"

Lot of help I am, huh?

But yeah, you do retain a lot of water and increase your blood volume in the weeks before birth. I believe it's helpful in delivery somehow....

[AmyKT]

Yep. Definitely water retention. I went up and down 5-7 pounds in the last few weeks because of water retention. I have just discovered that red blood cell counts go down in pregnancy because they are spread out due to extra fluid. I'm not sure if that is somehow helpful, though.

[Dee-Groovy]

I read that the baby gains about half a pound a week from 30 weeks until the end. Not sure where I got it or if it's true but it makes sense. That's about 5 pounds, and the baby is about 2.5-3 pounds at 30 weeks so the total would be 7.5-8 pounds.

I have also starting retaining water like crazy in the past week. What is that all about?

[DeChRi]

Thanks for the replies. I'm not sure why it's of interest to me, but I'm science-y like that, lol. I'm the textbook gainer. Start each pregnancy at very healthy weight, gain 30lb, give or take a lb or two, and then it all comes off quickly. I gain the textbook 5lbs in the first tri, then literally almost a lb a week exactly after.

This time I am curious as to where it is going and at what times...what is going on in my body, etc. My actual body fat amount is pretty close to pre-preg within a month or two usually, and I'm not much of a sweller at all. I don't thing I have any swelling that I noticed with my last two.

I've looked at all the weight gain charts and such. But heading into the third tri I find myself wondering, with this home stretch of weight gain, besides the baby, where does it go, and why?

[RedOakMomma]

Wouldn't some of it just go onto us as fat stores? I know our bodies naturally build up a fat reserve for nursing and extra energy demands of a new baby. I'm no expert, but it makes sense that in the weeks following the birth of a baby, when foraging and resource-gathering would be difficult, that our bodies would store up some extra oomph (that's my scientific word for it ) in order to get the baby through the early stages.

[Hannah32]

Well I'm not quite to the third yet, but am beyond my six month mark (24 1/2 weeks). I'm definitely noticing a decrease in appetite. Don't get me wrong, I eat, but I don't have the same ferocity that I had earlier. I don't know if I just overindulged and have gotten fatigued of some of my bad habits, or if I'm subconsciously worried about weight gain, so I'm trying to taper it.

[Dmitrizmom]

increase fluid retention is protective against hypovolemic shock should there be hemorrhage at time of delivery.

[gcgirl]

Originally Posted by RedOakMomma

There is some science behind the water retention, though I can't remember what it is at the moment. I think it was covered in Ina May's Childbirth book, maybe? Wish I could remember. It made a lot of sense, though, and when I read it in my last pregnancy I thought "wow...that makes sense!"

I start retaining water in the 3rd tri. My feet don't swell or anything until then, even this time around when I've gained only a net of 3 pounds since week 28. Contrast that to last time, when I gained about 15 pounds at the end! Huh.

[MaerynPearl]

Originally Posted by RedOakMomma

Wouldn't some of it just go onto us as fat stores?

According to myzymurgy thats about 7 pounds worth! which I suppose would be enough to get us through a while.

[AmyKT]

Originally Posted by RedOakMomma

Wouldn't some of it just go onto us as fat stores?

Originally Posted by MaerynPearl

According to myzymurgy thats about 7 pounds worth! which I suppose would be enough to get us through a while.

The thing is, I'm pretty sure I have already put on my fat stores, and I'm not even halfway through yet.

[BetsyS]

In my previous 2 pregnancies, I've had the smallest appetite in the 3rd trimester (biggest in 2nd), and yet, I've gained the most weight in the 3rd trimester. Odd.

I know that my babies put on a lot of weight in the 3rd trimester.

#1 measured exactly average at 24 weeks (ultrasound), By 41 weeks, he weighed 11 lb, 14 oz. Not so average.

#2 measured average at 8 and 20 weeks. By 38 weeks, he was measuring just a touch ahead. He weighed 9 lb, 7 oz at 42 weeks (and even calculating it out, he gained more than 1/2 pound a week between 38 and 42 weeks).

#3 has measured a week ahead at 12 and 23 weeks. I'll be curious to see how big he/she is!!

[RedOakMomma]

Originally Posted by Dmitrizmom

increase fluid retention is protective against hypovolemic shock should there be hemorrhage at time of delivery.

Bingo! That was it. Thank you, Dmitrizmom!

[Dmitrizmom]

Originally Posted by RedOakMomma

Bingo! That was it. Thank you, Dmitrizmom!

you are welcome.

I had direct experience with this when dd2 was born... I lost somewhere between 4 and 6 cups of blood, and will be eternally grateful to my midwife for her knowledge and to my body for having sufficient fluid to prevent me from going into shock and requiring transfer.

[DeChRi]

Thanks for all of the info!