Finding out you're pregnant can be a huge relief for once, your expanding waistline is cause for celebration, not dejection. Another chocolate biscuit? Oh, go on, then

But piling on the pounds when you're expecting is not recommended. The more weight you gain now, the harder it'll be to shed it later, so before you indulge your latest craving, read on.

Not worth the weight

Of course, getting back into your pre-pregnancy clothes more quickly is only one reason not to go overboard excessive weight gain is linked with various pregnancy complications such as high blood pressure and gestational diabetes. In extreme cases, these conditions could put your unborn baby's life at risk. You're also more likely to experience backache, varicose veins or pelvic problems. And women who gain too much weight are 75 percent more likely to have difficulty breastfeeding.

But pregnancy is no time to diet, either, as it can reduce birth weight, which could put your baby into the special care unit. University research suggests that babies of mums-to-be who were underweight or ate a poor diet are more likely to develop heart disease and diabetes. Dieting could also leave you short of key nutrients, leading to complications like anaemia, which can make you weak, dizzy and fatigued.

Slow and steady

So how much weight should you gain during pregnancy and how quickly? 'There's a basic 1-2-3 rule, which is associated with the best outcome for mum and baby,' says Fiona. 'If you were overweight pre-pregnancy, your optimum weight gain is 6kg. If you were a normal weight, you should gain about 12kg, and if you were underweight, about 18kg.'

Don't be surprised, though, if your health care provider doesn't keep tabs on your weight as they now use other technology such as ultrasounds and blood pressure checks. To avoid health problems (and stretchmarks!), you should gain slowly and steadily about 1-1.5kg in the first trimester, and around half a kilogram per week after that.

How to eat for two

Unfortunately, eating for two doesn't involve family packs of doughnuts. Pregnant women only need an extra 840 kilojoules a day and only in the third trimester (after 27 weeks' gestation).

It is important to eat a balanced diet, with a variety of foods so you don't miss out on key nutrients. Base your meals around low-GI carbohydrates, such as brown rice and whole wheat pasta, topped up with fruit and vegetables, protein, dairy products and small amounts of good fats.'

So, put simply, a good pregnancy diet is a balanced diet that will keep both you and your baby healthy.