With the incidence of twin pregnancies on the rise due to increased use of assisted reproduction technologies and older maternal age, diet during a twin pregnancy is a very important topic. Women carrying two growing babies must consume a highly nutritious diet, as well as be aware of the additional requirements from a typical singleton pregnancy diet.
Twin pregnancies are called a ‘high risk pregnancy’ because your body is required to feed and sustain the growth of two babies within your uterus. Twin pregnancies are known to have lower birth weight babies, are usually premature or delivered early for their dates, and are more likely to suffer from growth problems such as intrauterine growth restriction that can complicate your pregnancy. You are also more susceptible to developing hyperemesis and gestational diabetes, as well as more likely be nutrient deficient and gain inadequate weight. It is therefore especially important that you eat well during your pregnancy.
What changes occur in my body that will affect my diet?
- Increase in blood volume – The amount of blood in your body increases further by as much as 50% than a single pregnancy.
- Increase in basal metabolic rate – This refers to the speed of your body’s metabolism, which increases by at least 10% compared to singleton pregnancies. This equates to an additional 40% of your calorie intake if you were carrying only one baby.
- Increased calorie requirements – Carrying two growing fetuses in your body places a significant drain on your energy resources and depletes your stores at a much faster rate. Enough energy is needed to sustain the growth of ‘three’ beings. If diet is inadequate then your body will be put in ‘starvation mode’ and will rely on your muscle stores for energy.
- Higher hormonal changes – Hormones are found in far greater amounts in twin pregnancy, in particular beta-human chorionic gonadotrophin (bHCG). This hormone in particular is linked to causing nausea and vomiting symptoms, and you are more likely to suffer from the condition hyperemesis. See the page Nausea and Vomiting for further details.
How much weight should I gain?
Weight gain in twins is a particularly important topic. The pregnancy length is usually much shorter, hence the growing baby has a shorter period of time to grow and will experience its greatest growth at 31weeks, which is earlier in comparison to normal single pregnancy at 33weeks. This means that mum will experience not only earlier weight gain, but a faster weight gain. The weight gained during mid-pregnancy or around 20-28week mark has shown to have the greatest benefit on your babies’ birth weights and well being.
The following table provides a guide for the overall weight gain during your twin pregnancy:
What should my diet comprise of?
There is no specific diet available for you to follow throughout your twin pregnancy. There are however important changes to your diet, which your doctor should explain. Surveys have shown that 1 in 4 women receive no help with their diet when having twins, and of those that did 1 in 3 received incorrect advice.
Your diet during a twin pregnancy should include:
- An extra 3500 calories per day compared to your non-pregnant diet. This will however depend on your pre-pregnancy weight.
- 3 main meals with 3 small snacks during the day
- Meals should comprise of 40% carbohydrate, 40% fat and 20% protein mix, and be of low glycaemic index
- This will help stabilize blood sugar levels within your body and provide your growing babies with a continual supply of energy.
Nutrient demand will increase in twin pregnancy versus if you were carrying just a single fetus. Often supplements are encouraged as a nutritious diet supplying all this goodness can be difficult to sustain and nutrient deficiencies may develop.
- Multivitamin supplement – This is to ensure that you are receiving all of the desired nutrients. Having twins however doesn’t mean that you just ‘double’ your multivitamin tablets, as too much will provide your body with toxic levels of Vitamin A, which can be harmful to the babies. It is advised that you just take the standard dose – 1 multivitamin tablet per day.
- Iron – This is due to the increased volume of blood in your body and increased demand for red cells to carry oxygen around your body. Iron levels tend to drop naturally in pregnancy, however when expecting twins these will drop even further. It is recommended that you take Iron supplements to avoid an anaemic state, starting off with 1 Iron tablet per day (30mg). This may increase to 2 at some stage depending on your blood results.
- Folic Acid = Folic acid is important to avoid neural tube defects as discussed in the Folic Acid chapter. It is advised that once your doctor has confirmed that you are carrying twins, you should increase your folic acid intake to 1000mcg per day.
- Calcium = Calcium is needed to help build and maintain the strength of your babies’ developing skeletons, as discussed the Calcium chapter. As well as consuming 2-3 serves of calcium- rich dairy foods a day, it is recommended that you take an additional calcium supplement from second trimester onwards.
- Vitamin D = Vitamin D is also an important nutrient in helping strengthen your babies’ bones. The requirements for Vitamin D are the same as a single pregnancy, however you are more likely to be deficient with increased usage of nutrient to sustain three babies. It is recommended that you commence taking supplements of 1 tablet or 1000 units of Vitamin D a day, however this may increase depending on your levels.
What is the Brewer Diet?
A well known diet for women expecting twins or more babies is the “Brewer Twin Pregnancy diet.” This diet has been devised by an American doctor and website address for this can be found on the Links page. No randomized trial has been conducted on this diet however it does follow safe principles, but like any diet should be discussed with your doctor prior to commencing. This diet is based on the following principles:
- Based on providing a steady state of food to the baby, by consuming regular meals and not going for more than 12 hours without good food
- Daily diet structure consists of 3 main meals and 3 small snacks during the morning, afternoon and prior to sleeping snack
- Consists of the Brewer Basic Diet plus an additional 500 calories and 30g of high quality protein per extra baby