# What determines fetal size?



## Rainbow (Nov 19, 2001)

I'm just curious. Any theories or thoughts on what controls or determines fetal size? My latest was 12 pounds, 8 ounces at birth. My 2nd dd was 11 pounds so I guess I make big babies. Though my first was only 8 lbs 8 ounces.

Then I know others have full term 6 pound babies. I'm just wrapping my mind around it and curious what thoughts others have on what exactly determines the size of the baby.

Thoughts?


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## Pepper (Jan 25, 2004)

I think it's a combination of maternal diet and heredity. Also, on average, boys tend to be a bit larger at birth than girls.


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## Rainbow (Nov 19, 2001)

so, does high protein=large baby? I just naturally crave and desire high protein foods during pg, and feel woozy if I don't get enough... would that explain it in part you think?


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## Artisan (Aug 24, 2002)

I have read that a number of factors contribute. The biggest contribution is uterine conditions. (Smoking, nutrition, etc.) (I have read that high protein diets do lead to bigger babies. Or rather, it allows a baby to reach its full potential.) The other big contributing factor is genetics (particularly of the father).

My mom was very strict about eating 100 grams of protein every day when she was pg with me. I was her first and weighed 9lbs 10oz. With her second baby, she just ate what she felt like and had an 8lb 2oz baby. With her third, new husband (new genes!), she was under a lot of stress, and the baby was 7lbs 14oz.


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## pamamidwife (May 7, 2003)

I think a big piece is genetics.

I had a client who smoked who had a 9 1/2 pound baby.

Another piece is nutrition - but I really wonder how much this contributes. I've seen moms who could barely keep anything down the entire pregnancy have 8 pound babies.

I think there's still so much we don't know.


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## Storm Bride (Mar 2, 2005)

I've eaten very well with both my babies (and the one I'm building right now). But, to be honest, I was much more rigid about nutrition with my son. He was 7lb., 12oz. Aside from being a little more casual with my eatings habits, I behaved the same way when I was pregnant with my daughter. She was 10lb., 2oz.

As my children had different fathers, I'm inclined to think that genetics are the biggest factor. My ex was a 7lb., 10oz. baby, and my husband was 9lb., 13oz. (his brothers were all over 9lb., as well). If this baby ends up being 7lb. or something, then I guess I was wrong. :LOL


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## Greaseball (Feb 1, 2002)

With #1, I ate mostly sugar and processed crap, and not very much food at all. I gained 17 lbs, baby was 7/8.

With #2, I ate a high-protein diet; I mostly adhered to the Brewer diet with a bunch of extra desserts thrown in for good measure. I was eating about 85 grams of protein a day, sometimes over 100, and gained 50 lbs. Baby was only 8/9.

So it looks like it was totally random...


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## USAmma (Nov 29, 2001)

I too think it's genetic, or maybe it's that the body knows just how big a baby to grow (barring GD and other medical issues).

My mom had all 8 pounders, except my brother who was special needs. My dh's mom h ad 6 pounders. Dh and I had 7-4 (full term) and 6-13 (2 weeks early) babies.

I ate a lot of protein, esp with Abi's pregnancy because I'm veg and I wanted to be sure I was getting enough. I gained 65 with Abi, 45 with Nitara (was on terbulatine which probably burned a lot of calories). So obviously I was getting enough to eat!! Nitara's placenta was on the small side but healthy. Just like she was.


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## Debstmomy (Jun 1, 2004)

Ok then I have another question, if I can add to this thread???

Some babies born at 6 lbs & others at 9lbs or more are all considered normal. What do those moms measure? Are the 6 lbs Moms measuring 40 cm, along with the bigger babies???

I had 8+ lb babies & have always measured right on.

Just curious.


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## Rainbow (Nov 19, 2001)

Quote:


Originally Posted by *Debstmomy*
Ok then I have another question, if I can add to this thread???

Some babies born at 6 lbs & others at 9lbs or more are all considered normal. What do those moms measure? Are the 6 lbs Moms measuring 40 cm, along with the bigger babies???

I had 8+ lb babies & have always measured right on.

Just curious.

I measured far past my "week" with my 2nd who was 11 pounds. I think at her birth I was measuring 46 cm. With my 3rd I measured 36 cm at 41 weeks (when she was born) and she weighed 12 pounds 8 ounces. Isn't that strange? I was convinced I was having a smaller baby. My 2nd didn't engage until labor though and my 3rd was enaged for along time before labor. I geuss that played into my measuring more than anything. Neither pregnancy did the midwife think I was having a large baby- both though 8-9 lbs :LOL

So, as far as genetics... DH was 9 lbs and I was 10lbs... so it makes sense that plays a big part. DH is 6'4 now, so he isn't a little guy. I'm 5'3 though.

It is just so interesting to me... the whys and hows of different sized full term babies.


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## Mom2baldie (Oct 29, 2002)

*Some babies born at 6 lbs & others at 9lbs or more are all considered normal. What do those moms measure? Are the 6 lbs Moms measuring 40 cm, along with the bigger babies???*

I just wanted to answer Debstmomys question with my experience with my
last baby:

My DD was born at 9 lbs 10 oz and I NEVER measured over 36 weeks pregnant! (She was born at 41 weeks gestation) In fact, the entire pregnancy I always measured AT LEAST 2 weeks behind. My midwife never worried, but I did a little bit so I just ate constantly. Foods very high in protein because I figured that the baby must be really small and I wanted her to grow! I think I was also worried because I was still nursing my 2.5 year old and wondered if maybe that was taking away from the baby...


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## WinterBaby (Oct 24, 2002)

I expect there's probably a genetic component. But that said... anecdotally...

I totally blame the Brewer diet I was keeping for my daughter's slighly above average size


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## USAmma (Nov 29, 2001)

I measured exactly on with Abi (7 pounds 4 oz). Nitara was frank breech for awhile so my measurements were 2 cm behind for most of 3rd trimester, but at the end she flipped and I again measured right on.

My OB said that he looks for consistency with measurements more than the actual numbers, and that being off one way or another could be to baby positioning or the size of the mother (if she's overweight or underweight).


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## Greaseball (Feb 1, 2002)

With #1 (7.5 lbs) I measured right on target. With #2 (just over 8.5 lbs) I measured 3-6 weeks ahead from the start.


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## orangebird (Jun 30, 2002)

I measured right on target with my 8 1/2 pound baby, I was measuring 3-4 cm ahead most of the pregnancy with my 7 1/2 pound baby.


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## applejuice (Oct 8, 2002)

Quote:


Originally Posted by *Rainbow*
Any theories or thoughts on what controls or determines fetal size?

Heredity

Maternal diet

Maternal size...


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## ~*~MamaJava~*~ (Mar 7, 2004)

I always wonder about this too. My mom had all 8lbers, and I'm not a tiny girl (I'm 5'9) so I figured me and my 6'5 DH would produce big babies. But no! His mom only had 6 and 7lbers (all 12 of 'em), and our boys have been smallish. I gained 22lbs with #1 and he was 7lbs3oz, and I gained 30 lbs with #2 and he was only 6lbs 8oz. Neither of them had very much fat on them. My diet was healthy, but not huge.
It's weird to me because a lot of my friends are having high 8's and 9lb babies, and they're a lot smaller than me height-wise. They have been gaining a lot more weight than me, though, but I don't think that always means a bigger babe.


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## wendy1221 (Feb 9, 2004)

I've been wondering this too. I'm short (5'3) and dh is short (5'6) but our ds (my ds2) was 9lbs 4oz at 38 weeks. My first ds's father is 5'10. Ds1 was 8lb 8oz. He was 4 days late according to their edd, but closer to 2 weeks late, IMO. All of my my mom's babies were 6-7.5lbs except for my one broher who was 8lbs6oz. My dad's mother on the other hand had big babies. My dad was her first at 9lbs 4oz. And both of my uncles were over 7lbs despite her being Rh- and having 3 Rh+ boys (she was VERY VERY sick w/ her 2nd and 3rd babies.) If she hadn't had he sickness from the Rh incompatability, the other 2 probably would have been about 10lbs, we figure. She lost weight w/ her 2nd and 3rd prenancies.

My MIL had 7lb babies (4 boys). Her largest was 8lbs.

Now my sister is 3 inches taller than me and her dh is over 6ft tall, an dher 2 boys were 7-12 and 7-14. She follows the Brewer diet like I do.

So who he heck knows?


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## NYCVeg (Jan 31, 2005)

Dh was 6/2 (smallest baby in the regular nursery), I was 6/8, my sister's baby was 6/6. I think we're probably just small baby people (I'm petite and small-boned, as is my mom, so I guess it makes sense). My mom's biggest of 4 was 8 pounds. If my first ends up being a 10-pound baby, though, I'll let you know!


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## KarenEMT (Aug 10, 2002)

Very good question! I was born at 9 lb 7 oz and my DH was only 6 lb 4 oz. Our children were 8 lb 14 oz (37 weeks) and 10 lb 9 oz (41 weeks). In our case, it is my side of the family with larger babies, in fact, my great-grandmother was born in 1899 and weighed 10 lb. Her birth was so traumatic that her mother was never able to get pregnant or birth again. DH's family has had no babies over 7-1/2 lb.


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## mahogny (Oct 16, 2003)

My kids were practically the same weight: DS was 7lb 2oz, and DD was 7lb 5oz. So, just 3 oz different, but then again, DS pooped before he was weighed, so maybe he was 7lb 5 oz at birth like DD was! :LOL

DD was 1.25 inches longer, though.

I ate well during both pregnancies (no junk, no processed stuff, etc) but I know I ate quite a bit more protein with DD. However, as their weight difference was only 3 oz, in my experience, I'm inclined to say that genetics/heredity was the biggest factor in my kids' sizes.


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