What determines how heavy your baby is at birth?

[turquoise88]

I mean, aside from babies who are born very early and obviously small(er).

There probably isn't a definitive answer but it got me thinking. The last three women I've known to give birth are all what I would deem to be slim build (size 8/10) and have had big babies (9lb +).

I know some curvier women with higher BMIs and almost all have given birth to babies between 5lb and 7.5lb.

Is it weird to assume there would be a correlation between the weight of a mother and the weight of a baby?

I don't really know what the point of this thread is, other than I'm interested!

My midwife told me that birth weight was a combination of the baby's genetics and placental function - but I'd be interested to hear other views.

I don't know either. I had a 7lb-er and two 10lb-ers

I put on a LOT of weight during my pregnancy and had a 8lb 15oz son. I always just thought that I ate lot so he was a biggie!

I honestly thought it was how much you ate in pregnancy. Mine were all born term but early (37--39weeks) and were 6lb15, 6lb04 and 7lb09. The first 2 I was much healthier, the last one I ate rubbish.

Erm, in my case perhaps too many biscuits!

Larger mums (much larger than average) can have very small babies as space for growth is restricted.

Mine were 9lb and 11lb.

I’m 5’10, size ten and didn’t eat much with either because of awful sickness and heartburn. So who knows?!

Mine was 10lb+
I was tall and slim. I did eat loads though whilst pregnant. Put on 4 stone but still left hospital in my size 8 jeans. I’m convinced it’s the amount I ate. I lived on toast mainly.

I am very overweight (BMI 40) and assumed I’d have a massive baby. He was 6lb 10 oz at a week overdue so quite petite. The midwives told me that they’d have expected me to have delivered a baby of at least 7lb at 40 weeks given my size so I had growth scans in the next pregnancy. He was bigger but still not huge at 7lb 7oz at 39+3

I think its mainly genetics..unless theres medical issues. Gestational diabetes can cause bigger babies, problems with placenta and smoking is known to possibly produce smaller birthweights.
Mine were 7lb, 7lb 7, 7lb and 7lb 3.
Im a small 5ft 3, 8st and their dad was 6ft 2, 13st. All mine were long legged but thin.
I also do think diet might play a part too.

The personalised GROW charts they plot growth on certainly assume that bigger women have bigger babies. I was referred for low growth because even though I wasn't measuring much below average I was 'supposed' to have a bigger baby because I'm 5'10 and my BMI was 26 at booking in. They kept asking me if DH is short (he isn't). So yes, there is supposed to be a correlation between maternal size and baby size, but it isn't exact. DS was born 7lb1 and perfectly healthy - though he did then almost immediately shoot up from 25th to 75th centile and has stayed there so far (he's four months), so maybe he was supposed to be bigger!

Well I'm 5 foot 3 and slim. With my second baby I was throwing up a lot from weeks 10 - 30. I also lost my appetite completely and had to force myself to eat. I worried myself stupid that the baby was suffering because of this and that he would be tiny. I put virtually no weight on. Baby was born a very healthy 9lb. So in my case it wasn't what I ate that caused a bigger baby. God knows what did cause it though as babies in mine and dh's family are generally on the smaller end of the scale.

I'm naturally quite small, put on a lot of weight when pregnant (with my third I put on over 4 stone!) and my babies have weighed:
8lb 5oz
8lb 1oz
9lb 13oz
&
7lb 2oz (she was teeny tiny!)

The first 2 were late, second 2 were early

So absolutely no rhyme or reason in my case
Although the bigger 2 were boys and smaller 2 girls
I was a very big baby myself though at over 9lbs

Has there ever been any studies on this I wonder?

It's genetics provided the pregnancy/Mum is healthy.

My Mum it tiny (4'10) her first baby nearly 9lb.

I am 5' was underweight when I got pregnant my first baby 7lb 6oz.

Subsequent babies I was healthy starting weight and had a6'3 partner - all 10lbers.

I believe I inherited genetically the ability to grow big babies and my partner made them extra long and therefore unusually heavy.

Consultant told me that it was to do with how good the placenta is (but I'm sure it's also down to genetics and diet)

Anyway, what he actually said was that the first placenta is usually OK and then the body gets better at making placentas until roughly the 4th baby and after that they start to diminish again. So if that was true (and I have probably forgotten his exact words) it would account for the increase in birth weight of my three 9lbs4oz, 9lbs13oz and 10lbs 5oz. :-0!

There must be a genetic element, but does it come from baby's dad? Me, DSis and our mum are all similar build. Petite, curvy but not overweight) Mum's 3 kids all 8-9lb. My 2 were 6lb, DSis had a 10lb and a 13lb 

They don't ask about the father for personalised growth charts - but I don't know if that's because they think it's less relevant than the mother or just because it's less practical to obtain (and indeed less certain!)

I only put on 7lbs during my pregnancy, as I'd lost loads of weight in the first 22 weeks as I was throwing up every day (and some nights too....)
My baby weighed 11lbs 5oz when he was born at 38 weeks.
They knew he was going to be big and had tested me (twice) for gestational diabetes, negative both times.
The midwife said I must have had really high quality placenta

I'm 5ft 6 and probably weighed about 14 stone when I had him
(I was 7lbs at birth)

I'm 5'3" and was size 6-8 pre pregnancy.

I lost 5kg in the first 12 weeks of and didn't gain until 28 weeks, I gained about 9 kg again (including the 5 I lost) by term. Delivered at 39+6 and DS was 8lb 11oz. I was 8lb at birth and his dad was 7lb9oz.

I lost weight with each of my pregnancies thanks to HG. I'm 5'3 and would be classed as slim. I also barely looked pregnant even at 40 weeks. My first child weighed 8lb 7oz and the other two were similar weights.

I had a consultant tell me "the best guide to the size of babies you'll have is the size of babies your mother had".

So basically he put it down to genetics. My mum had small babies, my sister and I had average babies. So not sure how good his theory is.

I was told I was having a normal sized baby. This was my third pregnancy and I knew they were wrong  I lost 3.5 stone during the pregnancy because I couldn't eat (there was no room)
Eventually I went into labour and with a lot of effort and stinging delivered an 11lb1 baby naturally with just gas and air. 

I had a consultant tell me "the best guide to the size of babies you'll have is the size of babies your mother had".

I was 3lb born.
My dp was 10 lb.
Ds1 was 8lb 12
Ds2 was 8 lb 10.ds 3 was 9 lb 2
Ds4 was 9 lb 1Da 5 was 8 lb 12.

So i think in this case they took on dps genetics

Ds 4 was 9lb 12

DS2 was 10lbs exactly and the MW high-fived me after having him, saying his placenta was almost as enormous as he was.

I always assumed the placenta dictates most of what a baby gets nutrient wise, so has greatest impact on their size.