Weight Gain During Pregnancy

How much weight will I put on during my pregnancy?

It is very normal for almost everyone to put on weight during their pregnancy - not only is your body going through huge changes but you have a baby growing inside you too. Weight gain during pregnancy can cause some women to feel quite worried. Common anxieties that midwives hear are 'am I putting on enough weight? or 'am I putting on too much weight?'

It is perfectly normal for a healthy, average-sized woman to gain between 22 and 26 lb (10 and 12 kg) when pregnant. Remember that you will be gaining the weight of your baby, the placenta and amniotic fluid. These will all disappear when you step on the scales after giving birth. To put it into perspective, your baby will weigh around 7.3lb (3.3kg) if you give birth at 40 weeks. The placenta that is responsible for all of your baby's nourishment, will weigh around 1.8lb (0.8kg) and the amniotic fluid which cushions your baby will weigh around 1.8lb (0.8kg).

There are other changes going on in your body that mean you gain weight during your pregnancy too. Your uterus has a layer of muscle that grows rapidly and ends up weighing an extra 2lb (0.8kg). Your body increases the volume of blood that circulates around it when you are pregnant, this weighs an extra 2.6lb (1.2kg). You also retain a lot more fluid which weighs another 2.6lb (1.2kg).

You may notice that your breasts have got bigger (which you may or may not be happy about!). Due to the hormonal changes in your body they will enlarge by an average of an extra 0.9lb (0.4kg) in weight.

Your body also builds up some stores of fat during your pregnancy. This is to support your baby and afterwards to give you the energy you need to breastfeed. This extra fat will weigh about 8.8lb (4kg).

There will be times in your pregnancy when you will gain more weight. Most of the weight you put on will happen in the forth to seventh month of your pregnancy, but this can vary from woman to woman. Your weight is unlikely to change very much in the first trimester (especially if you are throwing up or feeling nauseous).

What if I gain too little or too much weight?

There are downsides to gaining too little or too much weight during your pregnancy. Women who put on a very low amount of weight are more likely to have a premature or low-birth-weight baby. This is especially the case in women who also smoke, have a poor diet during pregnancy, have taken drugs or have drunk alcohol heavily.

Gaining a large amount of weight during your pregnancy also has its risks. You are more likely to feel breathless, have heartburn, develop varicose veins or haemorrhoids and you may experience some swelling. You will also have a higher risk of developing a complication like high blood pressure, gestational diabetes or pre-eclampsia.

If you are worried about the amount of weight you are gaining, speak to your midwife who will be able to give you some expert advice.

How can I tell if I am a healthy weight?

Every woman is different and has her own body mass index (BMI). You may see the term BMI written in magazines or on the side of cereal packets and you might have discussed your BMI with your doctor or midwife. Your BMI is a way of measuring your weight in relation to how tall you are, and it is an accurate way to tell if you are within a healthy weight range for your height.

Work out your BMI here by using your pre-pregnancy weight.

In the UK there are no official guidelines about how much weight you should gain during your pregnancy; even experts have a tough time trying to agree on it. As a general guide for a one-baby pregnancy:

Pre-pregnancy BMI BMI weight range Total weight you should try to gain during pregnancy Average weight gain per week 2nd and 3rd trimester

If you are less than 20 years of age, you should try to gain the weight at the top end of the range for your BMI (for example if you are in the ideal weight range, you should aim to put on 35 lb or 16 kg) during your pregnancy.

What if I have diabetes?

If you are diabetic you will need to try hard to keep your blood sugar levels as stable as possible during your pregnancy. Your doctor, midwife or diabetic nurse will advise you on the best diet to keep you and your baby fit and healthy. You will be given extra care throughout your pregnancy by doctors and nurses who are specially trained to look after diabetic mums-to-be.

What can I do to control my weight gain during pregnancy?

When you are pregnant it is no time to observe any strict diets, but equally it's not about throwing away the scales and literally eating for two! The best thing you can do is stick to a healthy, well-balanced diet during pregnancy by eating a variety of wholesome foods from the carbohydrate, protein, fruit, vegetables and dairy food groups. This way you will give your baby the healthiest start in life.

There's also nothing wrong with trying to stay fit and healthy during your pregnancy, read here for tips on good ways to exercise during pregnancy.