Poor nutrition during pregnancy can have long-lasting effects into an infant’s adult life, write Shelley Wilkinson, Susan de Jersey and Jane Karpavicius.
Have you heard the saying: “If there was one time I didn’t need to watch my weight or what I ate it was when I was pregnant.”
This is a common myth and a comment regularly heard by dietitians who care for pregnant women. Nutrition prior to and during pregnancy influences the health of both mother and child throughout the lifecycle.
In addition to overall caloric intake, pre-pregnancy weight and gestational weight gain, the diet quality can influence optimal fetal development and maximise growth, development, and a healthy life.
Diet quality in early pregnancy can influence how a baby's organs develop. Later in pregnancy, diet quality influences baby's growth and brain development. The once popular belief of the “parasitising foetus” (i.e. the baby never missing out and taking everything it needs from mum’s stores) is known to be untrue. Poor nutrition in utero can have long-lasting effects into an infant’s adult life.
What determines diet quality?
While some specific nutrients are important in pregnancy, a balanced diet that meets the Australian Dietary Guidelines and the Australian Guide to Healthy Eating is recommended.
While the recommended numbers of serves from the core food group serves for pregnant women have recently been the focus of a large review process (to be finalised late this year), the message is still the same; most food eaten each day should be from the fruit, vegetables/legumes, and wholegrain breads/grains groups, with moderate amounts of dairy products and meats (or alternatives), and small amounts of healthy fats and oils.
Pregnancy is a time where some nutrient needs increase significantly, with only a small increase in energy needs, rendering the quality of the diet imperative. Despite the “eating for two” myth, there is actually no increase in energy (caloric) needs in the first trimester.
The increase in energy required in the second and third trimester equates to approximately an extra two serves of fruit and a small amount extra of protein (e.g. tin of tuna or an egg). These guidelines meet the needs of most women, but adaptations may be required for some groups, such as vegetarians/vegans, young women, and those from culturally and linguistically diverse backgrounds.
Special nutrients during pregnancy
A woman following a well-balanced, nutrient-dense diet is more likely to meet her increased needs. Four nutrients are of particular importance during pregnancy: folate, iodine, iron, and vitamin D.
Folate (or folic acid) is essential for fetal growth and development. It is particularly important for the prevention of neural tube defects. In addition to a folate-rich diet, it is recommended that women take a 400mcg folate supplement in the month prior to conception and during the first trimester of pregnancy. Women still need to eat foods that contain folate. Rich dietary sources of folate include green vegetables, fruit, and fortified cereals.
A woman’s requirements for iodine increase during pregnancy and when breastfeeding. Iodine is involved in metabolism, growth and brain development. It is recommended all women take a supplement with 150mcg of iodine during pregnancy and breastfeeding in addition to dietary sources. Good dietary sources of iodine are fruit, vegetables, and fish. Iodised salt is obviously a source of iodine, however, increasing salt consumption is not recommended. Women with thyroid conditions should consult their doctor prior to taking this supplement.
A woman’s iron requirement triples during pregnancy. Good dietary sources of iron include red meat, fortified breads and cereals, green leafy vegetables, legumes, and some nuts. Women can help their body absorb more iron from non-meat (non-haem) sources by including Vitamin C rich foods at the same meal (e.g. tomato, capsicum, citrus fruits or kiwifruit). An iron supplement should only be recommended following confirmation of low iron by a blood test. Serum ferritin is the best indicator of a woman’s iron status.
Vitamin D keeps bones and teeth healthy and strong by maintaining blood calcium levels. Whilst vitamin D requirements do not increase during pregnancy, some population groups are at greater risk of having low vitamin D levels. These include women who do not have sufficient sun exposure due to climate/seasons, cultural reasons, or skin pigmentation.
Women at risk of low Vitamin D exposure should get their levels checked early in pregnancy. Supplementation should only occur on confirmation of low levels. There is only a small amount of vitamin D in foods including margarine or milk that has vitamin D added to it, oily fish (e.g. salmon, sardines, tuna, herring, and fish roe) and eggs.
Supplements during pregnancy?
The only routine supplementation required is for folate (400mcg per day one month prior to conception and for the first three months of pregnancy) and iodine (150mcg per day). There is no evidence that a multivitamin supplement is of benefit in a well-nourished woman, but this may be used as a source of folate and iodine.
Between a third and half of all women in Australia commence pregnancy above a healthy weight. A woman’s gestational weight gain goal depends on her pre-pregnancy weight. The Institute of Medicine (IOM) guidelines are based on a systematic review of evidence that evaluated the optimal outcomes for both mother and baby.
Gestational weight gain outside of these recommendations is associated with adverse outcomes during pregnancy, delivery and into the future beyond the immediate post-partum period. Women not advised of gestational weight gain guidelines are more likely to fall outside the recommended weight gain range.
Don’t diet during pregnancy
Restrictive dieting and weight loss are not recommended during pregnancy. A healthy and varied diet that is rich in nutrients will assist with positive pregnancy outcomes, including a healthy weight gain.
Focusing on normalising serve sizes of meals and snacks and minimising higher fat and sugar containing foods while replacing these with more nutrient dense and lower energy options, such as vegetables, salad, and fruit is important to achieving a quality intake. A balanced intake coupled with regular physical activity is important in achieving appropriate weight gain during pregnancy.
Other dietary issues
During pregnancy, hormonal changes weaken the immune system. Being careful with food storage, preparation and cooking is important to protect against infection. Listeria monocytogenes is a bacterium that is destroyed in normal cooking, so freshly-cooked hot food is safe if eaten straight away.
Bacteria grow over time, so women should avoid eating food if it has been more than 24 hours since being prepared, and they should always reheat to steaming hot. Comprehensive lists of “at risk” foods can be found on the Food Standards Australia and New Zealand website, and women should be made aware that even these foods can be eaten safely if heated above 74 degrees Celsius for more than two minutes.
Maternal nutrition has generational health effects; supporting pregnant women to make healthy food choices that contribute to a nutritionally complete diet can assist in achieving positive maternal and fetal outcomes. All women should be made aware of their expected weight gains. This may require the assistance of an accredited practising dietitian (APD) who can provide ongoing support for expert advice to achieve long-lasting change.
Shelley Wilkinson is an advanced APD at Mater Mothers’ Hospital, Brisbane, Susan de Jersey is an APD at the Royal Brisbane and Women’s Hospital and Jane Karpavicius is an APD at the Royal Women’s Hospital, Melbourne. They are all members of the Paediatric and Maternal Health Interest Group of the Dietitians Association of Australia, visit http://www.daa.asn.au
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