What does the size of your baby bump mean?

Bump size also depends on how many babies you’re having, which way your baby is lying and the amount of amniotic fluid there is in your womb.

Just as with most areas of pregnancy, there are many old wives' tales about bump size. So, we thought we'd let you know if any of them are actually true...

Does a big baby mean a harder birth?

No, it doesn’t. The size of your baby won’t influence the speed of your labour or how painful it is. How hard a birth is has more to do with the position that your baby is in and how relaxed you can stay during labour. Whatever size your baby is, the same advice applies: you need good support, to stay relaxed, and keep upright and mobile for as long as you can once you’re in established labour. And that's whether you’ve got a 5-pounder or an 11-pounder on board!

But aren't smaller babies easier to give birth to?

There’s a common misconception (excuse the pun) that little babies will pop out much more easily but there is nothing to suggest that this is the case. In fact, from my experience as a midwife, small babies can often take longer to make their journey than the bigger ones. I’ve known women who’ve tried to diet during pregnancy, thinking they'll have a smaller baby and so an easier birth – but they've got their information all wrong.

Large babies run in my family, does that mean mine will be large too?

Big babies can run in the family, as can small ones – but this can be as much to do with social factors as genetics. For example, if your parents are overweight, then you’re more likely to be, and therefore more likely to have a bigger baby.

In the same way, if your parents didn’t eat well or smoked, then it does the increase the likelihood of you following suit, which can increase the likelihood of a smaller baby. Diet and lifestyle do play a part in the size of your baby. For example, if you have a family history of diabetes, your midwife will advise a test for this, as this can also be the cause of a large baby.

Will a bigger bump put too much burden on my body?

Most women with a large bump don’t have any more problems than any other mum-to-be. But theoretically, carrying increased weight could cause increased pressure down below resulting in haemorrhoids (piles) or varicose veins of the vulva, which can feel like a real heaviness and discomfort between your legs. However big your bump, if you keep yourself healthy in pregnancy and take regular gentle exercise, there’s no reason why it should put too much strain on your body.

I’m underweight. Does that mean I’ll have a small baby?

At the beginning of pregnancy, your midwife will work out your body mass index (BMI). This is your weight in relation to your height and, ideally, should be somewhere between 19 and 25. If you’re significantly underweight and not eating enough, then, yes, this could result in you having a lower birthweight baby, or increase the likelihood of going into labour prematurely (before 36 weeks). What’s important is that you have a healthy balanced diet, and try not to go too long without eating.

What if I’m pregnant and overweight?

Women with a BMI of over 30 are at increased risk of complications, such as high blood pressure, diabetes and pre- eclampsia. Pregnancy isn’t the time to start a strict diet but, by eating sensibly and reducing your fat and sugar intake, you can help to keep your weight gain within a reasonable limit and reduce the likelihood of short and long-term health problems for your baby.

Whatever you do, don't believe the myth that you need to ‘eat for two’. You really don’t and if you gain a vast amount of weight it can be difficult to shift after the birth. Keep active, don’t deny yourself treats, but do follow a healthy balanced diet to increase the chance of a healthy pregnancy and birth.

Will my height affect my baby’s size?

Years ago, we did think a woman’s height had an impact on her ability to give birth, but this is no longer the case. What we do know is that babies tend to grow to fit. Nature rarely gets it wrong. If you’re 4’ 10” then the chances are that you’re not going to grow a huge baby. Having said that, even if you do, if a baby’s too big to fit through the pelvis then you tend to get signs during labour that things aren’t progressing.

Will a small baby be less healthy?

There’s a difference between a baby that’s small because he hasn’t grown properly in the womb – who may well have health problems – and a baby that’s just small and is the right size for you. Ideally, during pregnancy you’ll have a customised growth chart where your midwife will plot the measurement of your uterus each time she sees you, from around 25 weeks. If your baby’s small but right for you the growth will follow a curve, but if the growth is restricted the line will start to fall and you’ll need to be referred to an obstetrician who’ll monitor your pregnancy closely.

I’ve had really bad morning sickness. Will my baby be small as a result?

Your baby will take the nutrition that he needs from you and it’ll be you who’ll suffer. Hopefully, the nausea will get better at around 12 weeks. Sickness is often worse if you go for a long period of time without eating (which is why it’s commonly worse in the morning). Try to eat little and often, and drink plenty of fluids. When the nausea is really severe, women may have to be admitted to hospital for intravenous fluids to prevent dehydration. But the sickness would have to be really acute throughout
the pregnancy to affect the growth of your baby.

Will a big baby become an overweight child?

Again, this comes down to your baby being the right size for you. If you have a good-sized baby then chances are your body’s done a great job of helping your baby to thrive, and he’ll continue to grow at the right rate for him once he’s born. However, if you have a big baby because you’re very overweight and have eaten a diet that’s high in fat and sugar, then there’s an increased likelihood that your child’s diet will be similarly unhealthy and he may become an overweight child.

If my baby’s small when he’s born, how quickly will he catch up?

This depends on the reason why he’s small. If your baby is small because you are, then there is no catching up to do, he’s just the right size for him. But babies whose growth has been severely restricted while in the womb can take until the age of 3 to catch up with their growth. These babies often come out and feed constantly as though they’re making up for lost time. If your baby is small because he was premature then that’s very different, as when it comes to growth, you need to consider how many weeks old he would’ve been if he’d arrived when he was due.

Are there risks when giving birth to a big baby?

This depends on the reasons for the baby’s size. A big baby is defined by medical professionals as weighing more than 9lb 9oz. A baby of this size can be the result of uncontrolled diabetes, obesity, gaining too much weight during pregnancy, going two weeks over the due date, or could still just be the right size baby for you. There are plenty of women from these groups who go on to have an average size baby.

The vast majority of women expecting a large baby will have a normal vaginal birth and not encounter any problems, though increased risks associated with very large babies include shoulder dystocia (difficulty delivering the baby’s shoulders – usually resolved with a change of position) and increased bleeding after the birth.

Mums’ stories:

“Seth was 12 days late and I went from weighing 108lbs to 148lbs. A lot of people were asking if I was having twins because I was so big. Needless to say, he was too big to come out and they had to do a C-section. The munchkin weighed 8lbs 12oz.” Joy Charde, 34, from New York, mum to Seth, 1 month

“Before my pregnancy I was on the chubby side and it effected my self-esteem. But as my bump grew bigger, I gained confidence. I love the way my body shape is changing and realise that what people think of you shouldn’t really matter.” Mona Jetwa, 24, from Harrow, 32 weeks pregnant

“With Isla I had to go for growth scans because my bump was small. She turned out to be 8lb 11oz, but was head down from 20 weeks and didn’t move from this position. I think bump size is more dependant on the position of the baby.” Laura McCaskie, 26, from Cheltenham, mum to Isla, 15 months, and 30 weeks pregnant

Read more:

• Is this the biggest baby bump EVER?

• When will I start to look pregnant?

• Weight gain in pregnancy