Enough calories for two
The total energy cost
of pregnancy is estimated to be around 76,000 kcal (calories). This is
for a healthy woman gaining an average amount of weight. It sounds like
a lot, but don’t reach for the chocolate biscuits just yet. Changes to
your metabolism, and a reduction in exercise and general activity, mean
you don’t actually need to consume many more calories during pregnancy
than you usually do. In fact, for the first six months, women of a
healthy pre-pregnancy weight don’t need any extra calories at all.
Then, during the final three months, they need only an extra 200
calories a day. This is the time when the baby is growing rapidly and
laying down fat in preparation for birth.
Appetites vary
greatly and some women find that they are incredibly hungry at the
beginning of pregnancy, even though their baby is no bigger than a
raisin. This is due to hormonal changes and the adaptations that the
body is already making. Usually this settles down as pregnancy
progresses. Energy requirements also vary from person to person
according to a variety of factors, including weight and level of
physical activity. If you are underweight you may need extra calories
from the beginning. It is important to listen to your body but not to
use pregnancy as an excuse for overeating.
Early learning
What you eat now can
affect your baby for life. In the late 1980s, David Barker and
colleagues explored the idea that the risk of developing certain adult
diseases, including stroke and type 2 diabetes, was associated with
development in the womb. This is sometimes referred to as the ‘Barker
hypothesis’, but many researchers around the world have carried out
similar investigations. There is now a considerable amount of evidence
showing that nutrient intake during pregnancy affects birth weight.
Babies whose birth weight is towards the lower end
of the range have an increased risk of developing certain degenerative
diseases in adult life, including obesity, coronary heart disease,
stroke, type 2 diabetes and cancer.
The exact reason why is
not known, but it is believed that babies are somehow ‘programmed’ in
the womb. If they are undernourished before birth, then their body
adapts, ready for a life of food deprivation. When they are born into
an environment where food is actually abundant, their body can’t cope.
The real problem is the mismatch between the food supply in the womb
and their diet later.
In 2011,
research was published showing that what a woman eats during pregnancy
may affect her baby’s DNA. It was found that eating a low-carbohydrate
diet in early pregnancy could result in epigenetic changes –
alterations in the way specific genes work, while the genetic sequence
remains unaffected. A small adjustment to the baby’s DNA caused by a
low-carbohydrate diet was found to result in babies having more body
fat as children. The researchers were surprised by how significant a
difference early diet could make. The epigenetic changes due to a
low-carbohydrate diet in early pregnancy explained a quarter of the
difference in the fatness of the children six to nine years later.
Allergy-proofing your baby
If you have a family
history of allergies you may have heard that avoiding certain foods
during pregnancy could prevent your baby from developing allergies.
However, a number of studies have been carried out, in which some women
have avoided certain foods and others have consumed them, during
pregnancy. The results of these studies suggest that avoiding foods
such as peanuts, dairy foods, wheat or eggs during pregnancy is not
beneficial. It does not appear to protect a baby from developing
allergies and it can mean that both a mother and her baby miss out on
essential nutrients. However, there is some evidence
that you may be able to reduce your baby’s risk of developing allergies
by adjusting your diet in other ways during pregnancy.
A study of more than
2,000 pre-school children in the Bristol area looked at the incidence
of wheezing and eczema in relation to mineral levels at birth. It was
found that these problems were less common among children who had been
born with higher levels of iron and selenium.
This was found by analysing blood samples from the umbilical cords,
which primarily reflects the mothers’ dietary intake. So, ensuring a
good intake of iron and selenium could be valuable tools for allergy
protection .
Fish oils
have also been shown to help in preventing allergic conditions.
Australian researchers found that when pregnant women took fish oil
supplements, their babies were three times less likely to show signs of
egg allergy at one year of age. The researchers had hoped that the
supplements might also reduce the incidence of eczema, but this wasn’t
the case. However, although there were similar numbers of babies with
eczema in the fish oil group as in the placebo group, those with
mothers who had taken fish oil had significantly milder symptoms.
As well as getting plenty of iron, selenium and fish oils, some probiotics and prebiotics may also help when it comes to allergy-proofing. In one study, exposure
to probiotics before and after birth was found to be protective against
eczema. The trial involved Lactobacillus GG, which was given to women
with a family history of atopy (allergic conditions) from 36 weeks of
pregnancy until delivery. The women’s babies then received the
probiotic for six months either directly in formula, or via breast milk
when the mothers had it. At the ages of 2 and 4 years, children exposed
to the probiotic were much less likely to have eczema than those
receiving a placebo in the trial. Other studies have found that a
combination of several probiotics along with a prebiotic offers similar
protection. Some studies have not found a positive effect on immunity
from probiotics, and it may be that different
strains have different effects, and that dose and timing of exposure
are important. Although the interest in probiotics is still relatively
new, overall they appear to have positive effects for people with
allergies in the family.
Don’t let allergy warnings alarm you
There is no
need to avoid foods just because they are labelled with ‘Allergy
information’ or ‘Allergy advice’. This simply highlights ingredients,
such as milk and peanuts, that most commonly cause allergic reactions.
This is so that people with allergies to these specific foods don’t
miss them in a long list of other ingredients.
