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      Weight gain in pregnancy

      A weight off your mind

      Everything you need to know about weight gain in pregnancy

      Weight gain is a normal and natural part of a healthy pregnancy. Learn how much weight you should gain depending on your BMI, how to gain weight safely, and why dieting is not recommended.

      Weight gain: a natural part of pregnancy

      Weight gain in pregnancy is healthy, natural and necessary. Aside from the additional weight of your baby and increased fluids, your body gradually lays down some fat stores1.

      Your calorie requirement during pregnancy only increases in the third trimester, when you need an extra 200 calories per day.

      During your first and second trimesters your energy needs are the same as before pregnancy. Eating for two simply means maintaining a healthy diet: this will provide your baby with all the nutrients they need to grow and develop. After 28 weeks, you should consume around 200 calories more per day2.

      Your pregnancy diet supports you both, but until your third trimester, your recommended calorie intake is the same as for pre-pregnancy.

      How much weight should I gain during pregnancy?

      Weight gain during pregnancy depends on your pre-pregnancy weight, and varies a great deal from mother to mother. Most women gain between 10kg and 12.5kg (22–28lb) while pregnant, some of which is the weight of the growing baby1.

      Putting on too much weight during pregnancy can be unhealthy, but it's important not to diet and instead eat healthily.

      The table below3 gives a general guide to healthy weight gain. To determine your BMI, use an online BMI calculator, or your midwife will be able to work it out for you.

      BMI Approximate weight you should gain during pregnancy
      20 or less Between 12.5 and 18kg (or 28-40lb)
      20-26 Between 11.5 and 16kg (or 25-35lb)
      26-30 Between 7 and 11.5kg (or 15-25lb)
      30+ 7kg (15lbs) or less

      A nutritious diet for healthy weight gain in pregnancy

      Your diet supplies the wide range of nutrients your baby needs for healthy development. A varied, nutritious intake from all the food groups will provide essential vitamins, minerals, fats and protein while helping you stay within the recommended weight gain guidelines for pregnancy.

      If your gestational weight gain is above the recommended levels, your midwife may suggest making some changes so that you gain weight more steadily.

      Choose nutrient-rich foods when it’s time to increase your calorie intake to get the most benefit from your 200 calories.

      When it’s time to increase your calorie intake by 200 per day, be sure to choose foods that are nutritionally rich. Yoghurt, for example, provides bone-building calcium while a jacket potato is a good source of fibre and, as a carbohydrate, delivers a boost of energy.

      Healthy 200-calorie snack ideas:

      • A small pot of low-fat yogurt with seeds and berries
      • A small serving of hummus with raw vegetable sticks
      • A banana and oat smoothie made with 150ml of milk
      • One smoked mackerel fillet, shredded and mixed with natural yogurt, served with two oatcakes4

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      Weight loss during pregnancy

      Being overweight before and during pregnancy can put you at greater risk of developing high blood pressure and gestational diabetes. It can also increase your likelihood of premature delivery and birth complications, plus breastfeeding problems, such as being unable to initiate or sustain it5.

      However, once you become pregnant it’s not advisable to diet. This is because your developing baby is responsive to nutrient changes during the different stages of their gestational development, which can affect their own ability to utilise nutrients later in life, impacting on obesity in later life6.

      Your developing baby is responsive to nutrient changes during their gestational development, which can affect their own ability to utilise nutrients later in life.

      A small serving of hummus with raw vegetable sticks will count towards your additional 200 calories.

      Instead, focus on eating healthily, with a good balance across the food groups. A large study has shown that adjusting your diet to maintain a healthy bodyweight in pregnancy (rather than to lose weight) and following a normal balanced diet, is safe, effective and has no consequential effects on the baby’s birth weight7. Learn how to strike the ideal nutritional balance in our diet and development articles.

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      Being underweight in pregnancy

      If you’re underweight, your midwife will be able to advise you on the healthiest ways to gain the additional weight you need. You may need to be monitored closely to check that your baby is growing well. A healthy weight during pregnancy can reduce the risks of preterm birth or a low birth weight baby8.

      Provide the constant nourishment your baby needs by eating small meals and healthy snacks throughout the day.

      Foods containing healthy fats are an excellent source of calories and nutrients. Avocados, nuts and seeds are ideal. Wholegrain varieties of bread and pasta deliver slow-release energy and a healthy serving of fibre9.

      Eat little and often throughout the day for a sustained supply of nutrients to your baby.

      1. NHS choices. How much weight will I put on during my pregnancy? [Online] 2015. Available at:[Accessed October 2017]

      2. NICE. Weight management before during and after pregnancy [Online] 2010. Available at: [Accessed October 2017]

      3. Deans A. Your New Pregnancy Bible, The experts’ guide to pregnancy and early parenthood. 4th ed. London: Carroll & Brown Publishers Limited, 2013.

      4. Tommy’s. 200 calorie pregnancy snacks [Online]. 2014. Available at: [Accessed June 2014]

      5. Hilson JA et al. Excessive weight gain during pregnancy is associated with earlier termination of breast-feeding among white women. J Nutr 2006;136(1):140-146.

      6. Armitage JA et al. Experimental models of developmental programming: consequences of exposure to an energy rich diet during development. J Physiol 2005;565(1):3-8.

      7. Thangaratinam S et al. Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence. Obstetrical & Gynecological Survey 2012;67(10):603-604.

      8. Han Z et al. Maternal underweight and the risk of preterm birth and low birth weight: a systematic review and meta-analyses. Int J Epidemiol 2011;40(1):65- 101.

      9. British Nutrition Foundation. Dietary Fibre [Online]. 2012. Available at:[Accessed July 2014]

      Last reviewed: 29th July 2014

      Your baby's future health begins here

      Your baby's future health begins here

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