Dernière mise à jour : 30 mai 2020
While pregnancy is not the time to lose weight, women should not use their expanding bellies as a reason to eat more than is necessary. The amount of food a woman needs during pregnancy depends on a number of things including her body mass index, or BMI, before pregnancy, the rate at which she gains weight, age and appetite. All pregnant women should eat a variety of nutrient-rich foods each day. It may also be necessary to take a vitamin and mineral supplement if recommended by a physician.
Many women start off pregnancy with an overweight or obese BMI and many gain more weight than is healthy during their pregnancy. Research shows the risk of problems during pregnancy and delivery is lowest when weight gain is kept within a healthy range. Obesity during pregnancy is risky for both mother and child, with some risks including gestational diabetes, gestational hypertension (high blood pressure), Cesarean delivery, birth defects and even fetal death. If a women is obese during pregnancy, it also raises the chance her child will be obese later in life.
In UK, more pregnant woman than ever are overweight or obese.
Weight Gain Guidelines
The latest weight gain guidelines by the Institute of Medicine are based on a women's BMI before pregnancy. The amount of weight gained depends on which category the pre-pregnancy BMI lands in:
IMC = Weight (in kg) / (Height in m x Height in m)
Underweight: BMI below 18.5
Normal weight: 18.5 to 24.9
Overweight: 25.0 to 29.9
Obese: 30.0 and above
The weight ranges below are for a full-term pregnancy:
Underweight: 28 to 40 pounds (12,7 to 18,1kg)
Normal: 25 to 35 pounds (11,3 to 15,9kg)
Overweight: 15 to 25 pounds (6,8 to 11,3kg)
Obese: 11 to 20 pounds (5 to 9kg)
For twins, the recommendations naturally go up:
Normal: 37 to 54 pounds (16,7 to 24kg)
Overweight: 31 to 50 pounds (14 to 22,6kg)
Obese: 25 to 42 pounds (11,3 to 19kg)
There are no set guidelines for underweight BMI weight gain with twins.
Risks to you of being overweight in pregnancy
Being overweight increases the risk of complications for pregnant women and their babies. The higher a woman's BMI, the higher the risks. The increasing risks are in relation to:
miscarriage – the overall risk of miscarriage under 12 weeks is one in five (20%); if you have a BMI over 30, the risk is one in four (25%)
gestational diabetes – if your BMI is 30 or above, you are three times more likely to develop gestational diabetes than women whose BMI is below 30
high blood pressure and pre-eclampsia – if you have a BMI of 35 or above at the beginning of your pregnancy, your risk of pre-eclampsia is twice that of women who have a BMI under 25
blood clots – all pregnant women have a higher risk of blood clots compared to women who are not pregnant, and if your BMI is 30 or more the risk is additionally increased
the baby's shoulder becoming "stuck" during labour (sometimes called shoulder dystocia)
post-partum haemorrhage (heavier bleeding than normal after the birth)
having a baby weighing more than 4kg (8lb 14oz) – the overall risk of this for women with a BMI between 20 and 30 is 7 in 100 (7%); if your BMI is over 30, your risk is doubled to 14 in 100 (14%)
You are also more likely to need an instrumental (ventouse or forceps) delivery, and an emergency caesarean section.
Risks to the baby if you're overweight in pregnancy
Problems for your baby can include being born early (before 37 weeks), and an increased risk of stillbirth (from an overall risk of 1 in 200 in the UK to 1 in 100 if you have a BMI of 30 or more).
There is also a higher risk of foetal abnormality, such as neural tube defects like spina bifida. Overall, around 1 in 1,000 babies are born with neural tube defects in the UK. If your BMI is over 40, the risk is three times the risk of a woman with a BMI below 30.
These problems can also happen to any pregnant woman, whether she is overweight or not.
Bear in mind that although these risks are increased if your BMI is 30 or over, most women who are overweight will have a healthy baby.
In general, pregnant women need between 2,200 calories and 2,900 calories a day. A gradual increase in calories as the baby grows is the best bet. Here is an overview of how calorie needs change during each trimester:
The first trimester does not require any extra calories.
During the second trimester, an additional 340 calories a day are recommended.
For the third trimester, the recommendation is 450 calories more a day than when not pregnant.
Additional calories should come from nutrient-dense foods including lean protein, whole grains, dairy, vegetables and fruit. Avoid unneeded extra calories by cutting down on foods high in fat and added sugars such as regular soda, sweets and fried foods.
Top Tips for Eating Right During Pregnancy
The 40 (or so) weeks of pregnancy are a magical time. Keeping a healthy lifestyle throughout pregnancy, as well as before and after, is key for both baby and mother. Important steps to a healthy pregnancy include eating a balanced diet; gaining the right amount of weight; enjoying regular physical activity; taking a vitamin and mineral supplement if recommended by a physician; and avoiding alcohol, tobacco and other harmful substances.
Foods Fit for Mom and Baby
Moms-to-be need a variety of foods from all the MyPlate food groups. A balanced diet with a variety of foods can provide healthy women with enough nutrients for pregnancy. Safe food practices are important, too, since pregnant women are at higher risk of food poisoning.
Pregnant women need a balanced diet including:
Whole grains: Breads, cereals, pastas and brown rice.
Fruits: All types of fruits, fresh, frozen or canned without added sugars.
Vegetables: Eat a variety of colorful vegetables, fresh, frozen or canned with no added salt. Raw sprouts should be avoided.
Lean protein: Choose lean protein from meat, poultry, fish, eggs, beans and peas, peanut butter, soy products and nuts. Pregnant women should avoid eating tilefish, shark, swordfish and king mackerel, and limit white (albacore) tuna to 6 ounces per week. Deli, luncheon meats and hot dogs should be reheated if consumed.
Low-fat or fat-free dairy: This includes milk, cheese and yogurt. Unpasteurized milk and some soft cheeses that are made from unpasteurized milk also should be avoided.
Healthful fats: From foods such as avocados, nuts and seeds as well as vegetable oils including canola and olive oil.
Avoid extra calories from added sugars and solid fats, which can lead to unhealthy weight gain. Cut down on foods such as regular soda, sweets and fried snacks.
Physical activity can help manage weight gain. The activity guidelines for pregnant women are 30 minutes of moderate exercise on most, if not all, days of the week. Make sure to talk with a doctor before starting or continuing any exercise routine while pregnant.
For a Personalized Healthy eating plan and a regular check up, consult a Nutritionist or Dietician.
From Amandine - Nutritionist in London (South Kensington, Clapham South & work place visit)
For more info: firstname.lastname@example.org
Source: The Royal College of Obs and Gyn & The British Medical Journal