We explain how to gain the right amount of weight and still stay happy and healthy, with advice on pregnancy nutrition from Dr Yehudi Gordon – the man who helps a number of celebs to shift the baby bulges.

How much weight should I gain?
The amount of weight a woman gains during pregnancy depends on her Body Mass Index (BMI). If you don't know your BMI, calculate it by dividing your weight in kilograms, by the square of your height, measured in metres.

So if you weigh 60kg, and are 1,65m tall, the calculation would be as follows: BMI = 60 divided by (1,65 x 1,65) = 60 divided by 2,7225 = 22

If your BMI is less than 20 you would be considered underweight and your recommended pregnancy weight gain would be 12,5 to 18kg; with a BMI between 20 and 26 (normal weight) the recommended gain is 11,5 to 16kg and with a BMI of 27 to 29 (overweight) the recommended gain is 7 to 11,5kg.

Is there a pattern to the weight gain?
During the first trimester most women gain little, if any weight. By 20 weeks the average woman has put on a quarter of her total weight gain, gaining a further quarter by 30 weeks and the remainder during the last 10 weeks.

However, some women put on weight in spurts, so it’s important to look at overall weight gain and consult your midwife or your GP if you are concerned.

Where does the extra weight go?
With average pregnancy weight gain (13,6kg) the distribution would be approximately: baby – 3,5kg, amniotic fluid – 900g, placenta – 700g, womb – 900g, retained water – 1,8kg, breasts – 900g, fat – 3,2kg, blood – 1,4kg.

According to Doris Campbell, spokesperson for the Royal College of Gynaecologists and Obstetricians, "The weight that goes on around the middle, on the buttocks and upper thighs is the body's way of storing energy for foetal growth in late pregnancy, for the rigours of labour and for lactation.

"The fat is deposited for important physiological reasons and these same reasons should ensure it will be used up."

What if I’m putting on too much or too little weight?
"Pregnancy is not the time to restrict your dietary intake," Campbell goes on to say. "Even women who are overweight should expect to gain – you can’t feed a baby with body fat.

"Women are not weighed at regular ante-natal check-ups as much as they were in the past and this is partly to stop them worrying about weight. You should pay more attention to how well you’re eating rather than how much you gain.

"However, if you are concerned, speak to the health professionals monitoring your pregnancy."

Should I really be eating for two?
Contrary to the popular belief, most pregnant women do not need to double their food intake.

According to the British Nutrition Foundation, "It is only during the latter part of pregnancy that extra energy is needed: an increase of approximately 200 calories per baby per day in the last three months of pregnancy is recommended, although the needs of individual women will vary, depending on how active they are.”

Campbell adds: "It is very difficult for women to gauge their calorie intake so it's best to keep to the right foods and eat according to your appetite."

Which food groups should make up the extra calories?
Almost all pregnant women need to increase their intake of protein, certain vitamins and minerals such as folic acid and iron, and calories(for energy).

Eating several different- coloured fruit and vegetables each day will help you get the variety of nutrients you need.

Choose foods as close to their natural state as possible to maximise your chances of eating well: pick whole-grain bread or brown rice over refined white bread or white rice, and fresh fruit and veg over canned or processed.

How much weight do you lose during the birth?
The average woman loses 5,5 to 6,5kg during birth, leaving 5,5 to 9,5kg to shift in the following weeks and months.

How long will it take to shift the rest of the weight?
This varies greatly, however, according to the Institute of Medicine, evidence suggests that a year after giving birth, on average, women are still 1kg above their pre-pregnancy weight.

The important thing is to be realistic. It takes nine months for the body to prepare itself to give birth, so it's ludicrous that we expect women's bodies to spring back into shape immediately afterwards.

So why do all the celebrities I see in magazines seem to lose the weight so easily?
Dr Yehudi Gordon, an obstetrician who has cared for pregnant celebrities such as Jerry Hall and Elle MacPherson says, "Celeb mums have a vested interest in getting back to shape, because their public image is so important.

"But what new mothers must realise is that these celebs take time off every day, actively pursuing the result they want, with the help of a team of experts from nannies, to personal trainers to dieticians, etc." Since most of us aren't so lucky, we shouldn't beat ourselves up if it takes a little longer!