Weight gain in pregnancy: what's normal and when?

So, how much weight should you put on?

Let's face it. Being pregnant makes you hungry (well, after you've got over the feeling-sick bit). And, though most of us know full well that the idea of "eating for two" is a an old wives' tale, studies¹ show that 20% to 40% of pregnant women in the US and Europe are gaining more weight than is recommended.

There are no formal UK-specific health guidelines on weight gain in pregnancy. For most mums-to-be, with a healthy pre-pregnancy weight, doctors recommended gaining between 1 stone 11lbs to 2 stone 7lbs (25-35lb or 11-16kg) over the full 9 months.

In reality this means, “gaining one to five pounds in the first trimester and about one pound per week (or every 9 days) for the rest of your pregnancy for the optimal growth of your baby”, explains senior nutritionist Saidee Bailey, director of Perfect Start Pregnancy.

But according to British Journal of Midwifery’s Midwife of the Year 2014 Jacqui Tomkins, it’s crucial to remember that everyone is different. “It is a mistake to try to determine very concretely how much you should be putting on, as there can be a number of compounding factors,” explains Jacqui, who works at the London Birth Practice,

Emily N, who's a member of our MadeForMums community told us "I have put on 3 stone at 35 weeks, and it's ALL on the bump. I've still got my wee skinny legs and tiny boobs (so disappointing - no boob growth for me) and my face is not the way it goes when I've actually put weight on normally, if you get me. My baby is on the 95th centile at growth scans, so not small. I think the proportion of your body ie where the fat grows must be a very very individual thing."

Sophie J, another member of our community said "I am 11 weeks pregnant and seem to be gaining weight already. I know I will put on weight of course but I'm sure it shouldn't be this early on. I have always struggled with coming to terms with putting weight on as when I was younger I was really big and over the last 3/4 years I have fluttered from a size 6-10 and currently a size 8."

MFM community member Phoebe M, told us "I have put on about a stone so far - I'm 33+2. I was under 8 stone and my BMI was 17 before I was pregnant so needed to put on more but haven't. If you are eating normally and baby is growing well then I think that is fine."

How to calculate your recommended weight gain

Pregnancy weight gain recommendations vary depending on whether you’re underweight or overweight to begin with. The best way to work this out is by calculating your Body Mass Index (BMI). As a rule of thumb the heavier you were before you got pregnant, the less weight you should put on during your next nine months.

To do to this calculation divide your pre-pregnancy weight (in kilograms) by your height squared (in metres).

Then look at our pregnancy weight-gain chart, below, and see what's the recommended weight gain for you:

• BMI below 18.5 (underweight) – aim to put on 28-40lb (12-18kg)
• BMI 18.5-24.9 (normal) – aim to put on 25-35lb (11-16kg)
• BMI 25-29.9 (overweight) – aim to put on 15-25lb (7-11kg)
• BMI above 30 (obese) – aim to put on 11-20lb (5-9kg)
  

How fast should I put it on?

You're looking for gradual weight gain rather than pigging out and piling on the pounds. If you're already overweight you may need to be even more careful. A recent study of 44,000 US women, published in Obstetrics & Gynecology, found that women who were overweight or obese before pregnancy were 2 to 3 times more likely to gain more weight than recommended, compared with those of normal weight.

Here’s a guide:

• First trimester - most women don't need to gain much weight, which is good news if you're struggling with morning sickness. A few pounds, or less than 2kg, is fine in the first few months.
• Second trimester - gain three to four pounds (about 1.4 to 1.8kg) a month. Try adding more zinc – from foods like lamb, turkey, chickpeas, spinach and brazil nuts – notes Saidee. "Zinc is required for rapid cell growth and is really important in your second trimester as your baby starts to really grow,” she explains.
• Third trimester - gain three to four pounds (about 1.4 to 1.8kg) a month. Building up vitamin K stores – which help blood to clot – with foods such as banana, potato skins, Brussels sprouts, prunes and cabbage, is important this trimester, adds Saidee.

What if I’m having twins?

The typical weight gain for mums-to-be of twins is around 50% more than in a single pregnancy.

General guidelines for twin pregnancy weight gain are:

• Normal weight (BMI 18.5 to 24.9) – aim to put on 37 to 54lbs (17-25 kg)
• Overweight (BMI 25 to 29.9) – aim to gain 31 to 50lbs (14 to 23 kg)
• Obese (BMI 30 or more) – aim to put on 25 to 42lbs (11 to 19 kg)

Being pregnant with twins puts extra demands on your body, so paying attention to your diet will have lasting health benefits for you and your twins. It's one of the most important steps you can take to give your twins a good start.

Experts say you’ll need 50%-100% more of the essential nutrients too, such as folic acid, vitamin B12, iron and calcium, with twins. While the best way to get these is through food, nutritionists and some midwives recommend a daily pre-natal vitamin and mineral supplement.

Should I be eating for two?

No, despite the best intentions of your mother in law or elderly neighbour telling you otherwise, eating for two is definitely an old wives’ tale.

Amazingly though, the myth continues, and has even appeared in a top 20 list of the most believed old wives’ tales.

But, don’t be fooled into doubling portions, as “being pregnant is not an excuse to eat for two by any stretch of the imagination,” warns Saidee.

But surely I need to eat more – I’m growing a baby!

No. Sadly, that's not the case.

"You should eat the same amount as a non-pregnant woman (about 2000 calories) for the first 6 months," says nutritionist Anne Sidnell. "And then in the last 3 months of your pregnancy, you need just 200 more calories a day, while your baby has their biggest growth spurt and you create nutrient stores for breastfeeding."

Tempted as you may be to binge on buns while you've got an excuse for a big tummy, Anne says it's more important than ever to focus on the quality of your pregnancy diet. After all, you're nourishing a growing baby inside you.

Try to keep your food healthy and varied. This means lots of fruit and vegetables, and starchy foods such as bread, pasta, rice and potatoes, with moderate amounts of meat, fish and dairy.

How many calories should I eat during pregnancy?

Well, it all depends on factors such as your height, Body Mass Index, activity levels and how effectively you burn calories, but experts agree around 2,000 calories a day is about right for most women.

Once pregnant, you may need a few more calories, says Saidee:

First trimester – an extra 100 calories each day. This is equivalent to:

• One Ryvita with 15g reduced fat cheese and a tomato
• 50g smoked salmon
• Pot of low fat yoghurt
• One medium apple and 10 grapes

Second trimester – an extra 150 to 200 calories a day. This is equivalent to:

• One slice of toast with 1/3 can baked beans
• Medium apple with a teaspoon of peanut butter
• One egg omelette with 15g reduced fat cheese and handful of spinach
• Strawberries with tablespoon of crème fraiche and two mini meringue nests

Third trimester – an extra 200 to 350 calories a day. This is equivalent to:

• Small baked potato with 100g tuna mayonnaise
• Pitta bread with ¼ pot houmous
• Grilled skinless chicken breast with tablespoon of stuffing
• Fresh banana milkshake made with 200ml semi-skimmed milk

Why am I putting on pregnancy weight all over, not just on my bump?

That lovely round baby belly often comes with a few extra lumps and bumps on the thighs, bottom and even arms (but sadly, not always in the boob department).

Stored fat can make up 6lb to 8lb of pregnancy weight gain, while increased blood and other fluids account for nearly 10lb.

But while the birth doesn't mean an immediate return to pre-pregnancy outfits, it can be surprising how much weight drops, as MFM community member Jenny S found out. "I gained 3 stone during my pregnancy and everyone told me that I was eating too much and that I was never going to lose the weight. I lost 2.5 stone during the birth! My baby, placenta and water made up the majority of the weight I gained."

How much of this extra weight is my baby and the placenta?

At 40 weeks, your baby and all the important bits that go with your growing baby will account for approximately the following:

• Baby – 6-8lb
• Stored fat and nutrients – 6-8lb
• Increased blood volume – 3-4lb
• Increased fluids – 3lb
• Amniotic fluid - 2lb
• Enlarged uterus – 2lb
• Placenta – 1-2lb
• Bigger breasts – 1-2lb

Total = 24lb to 31lb (1 stone 10lb to 2 stone 3lb)

Will I be weighed during my pregnancy?

In the UK, pregnant women are weighed when they first see a midwife – but guidelines from advisory body the National Institute for Health and Care Excellence (NICE) warn GPs and midwives not to get the scales out routinely after that.

And for some ignorance is bliss.

“I really don’t want to know how much weight I have put on," says mum Elouize from our community, "and I will not be getting on the scales until I join Weight Watchers after I have my baby.”

What are the risks if I put on too much pregnancy weight?

Overweight pregnant women are up to three times more likely to need an emergency Caesarean, according to a report from the NUI Galway Dept of Obstetrics and Gynaecology.

Other risks of being overweight when pregnant include:

• Gestational diabetes
• High blood pressure (which can cause a serious condition called pre-eclampsia)
• Thrombosis
• Increased risk of bleeding after birth

And then, of course, there's the discomfort of hauling round a heavier pregnant body - and the thought of extra weight to lose after the birth.

MFM community member Adele told us "I had a massive growth spurt at 34 weeks and put on over half a stone in a fortnight. In total it must now be 3 and a half stone though most of that in the last month or so to be honest.

"I can feel where it's gone on more than you can see it (if that makes sense) and quite honestly I can't wait to get back to Slimming World as soon as I can! I really am not enjoying my double chin!"

What if I’m overweight already?

Many women who are overweight will sail through their pregnancies. However, it’s worth knowing that being overweight and having a high BMI (of over 30) could put you and your baby at risk of complications such as:

• Gestational diabetes
• High blood pressure
• Pre-eclampsia
• Early labour

During labour, being overweight might also mean you might have:

• Forceps or a ventouse birth
• A caesarean section
• Heavy bleeding after birth
• A blot clot in your leg (DVT; Deep Vein Thrombosis) or your lung (pulmonary embolism or PE)

But remember, you might not experience any of these complications; it’s just good to know about them.

Can my weight gain be harmful for my baby?

There’s an increasing amount of research that says, ‘yes’.

Gaining an excessive amount of weight during your pregnancy means there’s a chance that your baby will be macrosomic, or Large-for-Gestational Age (LGA). And whilst we all love a big bouncing baby, weighing 4.5kg (8.8lbs) or more at birth can have serious implications for you and your newborn.

Risks of having a Large-for-Gestational baby include:

• Increased chance of having caesarean section
• Trauma to the birth canal
• Shoulder dystocia – during labour your baby’s head is born but their shoulders get stuck
• Brachial Plexus injuries – damage to the collection of nerves around the shoulder during birth
• Facial nerve injuries – damage to the facial nerves during birth
• Birth asphyxia - your baby is starved of oxygen during labour

Some research suggests that women who gain more weight than recommended during pregnancy may be more likely to have an overweight child.

"Gaining too much weight in pregnancy may permanently affect mechanisms that manage energy balance and metabolism in the offspring, such as appetite control and energy expenditure," said study researcher Sneha Sridhar, a public health researcher at Kaiser Permanente division of research in Oakland, California.

"This could potentially have long-term effects on the child's subsequent growth and weight."

What are the risks if I don’t put on enough pregnancy weight?

Surprisingly, gaining too little weight may also lead to your baby becoming obese in later life. The same study found that 19.5 % women who gained less than the recommended weight also had children who were obese or overweight.

But being underweight or under-eating in pregnancy also has other risks including:

• Premature birth
• Having a small, weak baby with ongoing health problems

Should I try to lose weight while pregnant?

Dieting is definitely not recommended during pregnancy, but nutritionist Saidee points out that trying to focus on healthier habits is no bad thing.

“Maternal weight gain and nutrition have a really strong influence over not only maternal health but also the health and later life of the resulting baby,” she says.

Bouncing between trying to keep down anything at all, and cravings for unhealthy meals (burger and chips - we’ve been there), can be a struggle. "Try to stick to a balanced diet rich in fibre, folate, and a good mix of fruit, nuts and seeds, veg and protein,” recommends Saidee.

Some mums-to-be find they lose weight in the early weeks, sometimes caused by sickness, other times it just seems to happen.

“I lost weight each time in the first trimester,” says MFM community member Jules, where by nine weeks, she had lost a stone despite eating “like a horse”.

Importantly, health advisory body NICE warns against “restrictive or crash diets” as these “may increase blood ketone levels and could adversely affect the neuro-cognitive development of the foetus”.

Meanwhile, independent midwife Jacqui Tompkins says the really critical concern for mums-to-be who find they can’t keep food down is not loss of fat, but low fluid levels.

“Dehydration can put your baby and you at risk,” she says. “And that is much worse than losing fat.”

What about exercise?

Something like a simple pregnancy exercise workout can help you maintain a healthy increase in pregnancy weight. Also, having a good level of fitness during pregnancy may help make labour easier: the fitter you are, the better your stamina and your ability to cope with giving birth - at least that's the theory.

Be careful with your choice of exercise, though. Make sure you know which exercise is safe during pregnancy.

"Don’t take up strenuous activity if you’re not used to it," says specialist prenatal personal trainer Vicky Warr. "Choose a low-impact activity that won’t put pressure on your pelvic floor. Swimming and brisk walking are good - but horse-riding and trampolining are not advised.”

What if I’ve still not lost weight from my first pregnancy?

Losing our baby weight is something that many of us struggle with but it really is best to try and get back to your pre-pregnancy weight before you get pregnant again.

That’s because putting on weight between pregnancies has been shown to increase your risk of developing gestational diabetes and high blood pressure during subsequent pregnancies. In one study of 22,000 women in Northern California the women who developed gestational diabetes in their second pregnancy but who hadn’t developed it in their first were those who had had gained the most weight between pregnancies.

And in fact, it’s thought that even a relatively small gain of 1-2 BMI units (kg/m2) between pregnancies may increase the risk of gestational hypertension and gestational diabetes, even in women who are not overweight or obese according to a Swedish study of 151 025 women. It also increases the likelihood of giving birth to a large baby.

References:

^{1. Effects of gestational weight gain and body mass index on obstetric outcome in Sweden. Cedergreen et al. International Journal of Gynaecology and Obstetrics. 2006.Jun; 93(3):269.74. doi: 10.1016/j.ijgo.2006.03.002. Epub 2006 April 12}

Read more:

• What does the size of your bump mean?
• Does your bump size matter?
• Growth scans in pregnancy - crucial info you need to know