Weight, nutrition and pregnancy

Weight gain during pregnancy varies from woman to woman.

It seems widely accepted that the baby's birth weight is linked to the usual weight of the mother and her BMI, (body mass index), prior to her pregnancy.

It is therefore important for women wanting to conceive to assess their weight and if necessary address any weight issues before embarking on a pregnancy.

Preconceptual dietry advice can benefit any women thinking of trying for a baby as certain foods should be avoided, caffeine considerably reduced and no alcohol is advised.

Risks for overweight or obese women

During pregnancy, these women may have :
  • A surge of hypertension
  • Gestational diabetes
  • An increased risk of a caesarean section
  • An increased risk of phlebitis (pain and inflammation of a varicose vein).
  • An increased risk of problems requiring the baby to be transferred to an intensive care unit

A woman whose BMI is between 18.5 and 25 in the months before her pregnancy is likely to give birth to a child with a normal weight .
  • For women with a normal body size the average gain during pregnancy is approximately around 12 kg. .
  • The weight gain is 3 to 4 kilos more in women carrying twins.
  • In early pregnancy, 33% of the calories are needed to form the placenta and increase the volume of the breasts and uterus.
  • A balanced diet usually covers the energy needs of a pregnant woman.

The weight gain during pregnancy is gradual

  • It is moderate in the first trimester as the baby grows very little during this period.
  • It increases then from the 4th month: approximately 4 to 5 kilos.
  • Weight gain is more important in late pregnancy as the baby grows further, increasing your weight to aproximately12 kilos at birth.

During pregnancy - if you should gain weight suddenly or start to loose weight then medical advice should be sort.

In the UK doctors and midwives stopped weighing pregnant women as it caused anxiety and was not a accurate way of assessing how well their pregnancies were going.

Monitoring your weight whilst pregnant can be useful if you are over or under weight at the start of your pregnancy. Weight yourself monthly, at the same time, preferably after fasting and on the same scales is most accurate.

If your weight gain is high, you will require advice and support from you GP or health visitor after your pregnancy.

Monitor your diet without depriving yourself and do not eat for two

  • A pregnant woman must not decide to start a diet : all diets are contraindicated during pregnancy, except those prescribed by your doctor, for example, gestational diabetes.
  • Do not miss meals, or restrict your diet, or this could deprive you and your baby of essential nutrients, vitamins and necessary calories.
  • A healthy and balanced diet is recommended.
  • Do not double up on calories
  • Eat a good variety of fresh foods to help increase your intake of certain nutrients essential for growth and development of the fetus.

A woman who is overweight or obese, excessively thin or who has diabetes should see a dietician for advice.

Never start a diet without medical advice.

Indulging and avoid excesses

  • Reduce consumption of tea and coffee .
  • Do not skip meals
  • Have 4 or 5 balanced meals each day: breakfast, snack around 11 am, lunch, tea, and dinner
  • Have a proper breakfast
  • Remember to "eat twice as well, not twice"
  • Eat 5 fruits and vegetables every day
  • Eat fruit in the form of sugar free fruit juices, at breakfast or around 4pm.
  • Do not snack between meals
  • Eat slowly, chewing calmly.
  • Calcium, Iron and Vitamin D can be prescribed in cases of identified food deficiency.

Caution is needed if the previous pregnancy occurred less than 2 years ago, if a strict diet has been followed in the weeks preceding the start of pregnancy, if the mother is overweight or too thin and when she has diabetes...

Food supplements or fortified products for pregnant women

Food supplements including vitamins, minerals or antioxidants, which come in the form of capsules, phials or herbal teas.

Many are not recommended for pregnant women.

Check with your GP first as some food supplements are unnecessary and can sometimes cause risks, for example Vitamin A can cause birth defects.

Folic acid is a supplement that is recommended especially during the first 3 months of pregnancy.

Treatment with folic acid

Folic acid reduces the risk of fetal neurological abnormalities.
In particular, a folic acid deficiency can cause neural tube defects such as spina bifida.

It is recommended to take folic acid before conception, and taken for the first 12 weeks of pregnancy.

For most women a 400mg dose is recommended however, the following women require a higher dose of 5mg;
    • Diabetic
    • taking antiepileptic drugs
    • have sickle cell disease
    • have had a previously affected pregnancy
    • have coeliac disease
    • women having twins
    • and poor nutrition.

Drink enough water

  • Drink plenty, between 1.5 and 2 liters of water per day
  • Absorption of water reduces the risk of urinary tract infections and constipation.
  • After the birth of baby you should continue to drink plenty of water, especially when breastfeeding.
  • Have a glass of milk at night before going to bed

The food you need


  • Calcium is important for healthy bones and the formation of the baby's skeleton.
  • It is provided by milk and dairy products.
  • It is advisable to consume three or four dairy products per day, or about one at every meal, such as milk, cheese, yoghurt, cheese.
  • 1 glass of milk equals 1 yoghurt 125 grams or 20 grams of cheese.

Do not consume dietary supplements containing calcium.

Vitamin D

Vitamin D increases the body's capacity to absorb calcium from food.
  • The need for vitamin D is doubled during pregnancy, therefore protecting your baby from deficiency.
  • Vitamin D is mainly synthesised by the body through the action of sunlight on the skin.
  • Vitamin D is found in oily fish, salmon, sardines, eggs and dairy products.

Some doctors will recommend Vitamin D supplements
  • Pregnant women often lack Vitamin D particularly in late pregnancy and winter.

Vitamin D is only prescribed by the doctor and the midwife.


An adequate intake of iron is essential especially late in pregnancy. Iron deficiency causes anaemia which is due to a lack of red blood cells. Such a situation could increase the risk of prematurity and low birth weight babies.
  • Iron rich foods should be eaten regulary, including eggs, fish and meat and vegetables, lentils, beans, chickpeas, oilseeds, spinach ...
  • Vitamin C aids the absorption of Iron, such foods as lemons, oranges, grapefruit and broccoli all contain vitamin C
  • Iron treatment may be prescribed if iron intake is insufficient or if anaemia is detected.

Do not take iron in the form of medicine or fortified foods or supplements. It could be harmful in cases of hypertension, diabetes or if you did not quit smoking.

Folic acid or Vitamin B9:

  • Green vegetables are rich in Folic acid which is involved in fetal development.
  • spinach, watercress, chicory, sweetcorn, cantaloupe melon, chestnuts, walnuts, chickpeas
  • Lettuce, green salad, endives, kale, leeks, artichokes, green beans, peas, radishes, asparagus, beets, zucchini, avocados, lentils, eggs, cheese, carrots, tomatoes, onions, corn, peppers * ... Bananas, kiwis, berries, dates, figs.

A deficiency in folic acid can cause abnormal development of the placenta, growth retardation and fetal neurological abnormalities and an increased risk of prematurity.

Folic acid is recommended before conception and during the first trimester (until the end of the third month of pregnancy).


Iodine is essential for the functioning of the thyroid gland and the proper development of the baby's brain.

Iodine is :
  • In shellfish, saltwater fish
  • Milk and milk products
  • Eggs
  • Iodised salt


  • Carbohydrates are the staple diet of the fetus .
  • Eat carbohydrates such as starchy foods, cereals and bread for example.


Proteins are often found in meat, fish, eggs and dairy products.


Eat as much fruit as you like


The amount of fibre is 2 times higher in wholemeal bread than white bread .
Fibre in your diet is essential to help prevent constipation - a common complaint in pregnancy


Fish is a food rich in many nurtrients
  • It provides good amounts of iodine, selenium, iron, vitamin D, vitamin B12 and especially omega 3, essential for the development of the baby and its brain.
  • Two portions of fish per week is recommended. Oily fish is especially good for you, such as salmon, tuna, sardines, mackerel, herring ...
  • Avoid eating shark, marlin and swordfish and limit the amount of tuna you eat as they contain high levels of mercury that can harm your baby's developing nervous system.
  • Only eat cooked shellfish as raw has the possibility of causing food poisoning.

Foods and Drinks to be avoided

It is recommended to limit and avoid the consumption of certain foods.
  • Limit your tea, coffee and coca-cola intake.
  • Soy products and soy: these products contain plant estrogens that can affect babies. As a precaution it is recommended to limit the consumption of these foods or products.
  • Alcohol and tobacco should be avoided: they increase the risk of prematurity and low birth weight.
  • Avoid Liver or liver products : they contain high concentrations of vitamin A which can harm your baby. Vitamin A and fish liver oil supplements must also be avoided.
  • Decrease consumption of butter, oils ..
  • Avoid dishes which are too spicy, or too fatty.
  • Moderate consumption of sweet foods, biscuits, pastries, sweets, chocolate ...
  • Diet foods are not recommended .
  • The consumption of sweeteners is not recommended.
  • Avoid eating peanuts in families with a history of allergies and or hayfever, eczema and asthma. Peanuts can cause food allergies in the baby.

Situations and people who require nutritional advice during pregnancy

  • A pregnant teenager
  • A woman expecting twins or triplets
  • A woman who has had several pregnancies in quick succession
  • A woman who is vegetarian or vegan (risk of deficiency in vitamin D, vitamin B12, iron, iodine, calcium).

Women pregnant with twins, do not always feed themselves sufficiently.

More Information
Smoking - http://smokefree.nhs.uk/
Alcohol - http://www.nhs.uk/chq/Pages/2270.aspx?CategoryID=54&SubCategoryID=131
Folic Acid - http://www.nhs.uk/Livewell/pregnancy/Pages/Folicacid.aspx
Exercise - http://www.babycentre.co.uk/pregnancy/fitness/exerciseguide/
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