During the famous Dutch famine of 1944–1945, the daily nutritional intake of pregnant women was reduced to only approximately 400–1000 calories, which is well under the 1800-2400 calories recommendation. As a result, infants who were subjected to mid or late gestation calorie restriction were born lighter. Later in adulthood, these children also experienced reduced glucose tolerance. But interestingly, children whose mothers were exposed to the famine during early gestation had a normal weight at birth but higher body mass index in adulthood.
These puzzling results led early researchers to the “foetal origins” hypothesis, which proposes that the in utero environment can set the trajectory for the subsequent development of childhood or adult diseases. For example, a foetus starved in the mother’s womb may be more likely to develop obesity, diabetes and other conditions later in life.
Although the Dutch famine is a rather extreme example of unfavourable in utero environment, it is now well recognised that lifestyle factors such as nutrition are crucial even from the early stage of preconception planning.
With almost an infinite number of food choices nowadays, many people are actually more confused than ever as to what they should eat. The 2013 Australian Dietary Guidelines suggests that healthy women can meet their nutritional requirements by eating a balanced diet, with a focus on whole foods rather than supplements. However, pregnancy increases the daily requirement for some key nutrients to provide for the growing foetus, making it sometimes helpful to use supplements if a woman is at risk of deficiencies.
Folic acid is one of the most well-known pregnancy supplementations for preventing birth defects such as neural tube defects. In fact, folic acid is made mandatory in bread-making wheat flour in 2009, which drastically decreased the occurrence of neural tube defects by 300% each year.
In addition, a large-scale study involving 65,643 pregnancies shows that folic acid supplementation is also beneficial to reduce the risk of miscarriages, which occur in at least 15% pregnancies. The new findings revealed that folic acid supplementation is more beneficial when started well before conception. Women who started supplementing at least 3 months before conception had a 10% lower risk of miscarriage than those who started 1-2 months before conception or after conception.
Therefore, regular folate supplementation (0.5mg daily) is recommended to sexually active women. A tenfold higher dose may be needed for women who have obesity, pre-existing diabetes, a known MTHFR mutation, multiple pregnancy, epilepsy diagnosis, or a history of neural tube defects. Ideally, supplementation should begin 12 weeks before conception to ensure abundant stores.
Thyroid activity increases during pregnancy, accompanied by an increase in the recommended daily intake of iodine (220mcg/day). When iodine intake is inadequate before conception, the foetus may not acquire enough iodine during pregnancy, leading to detrimental effect on its early brain development. This could mean infant death or affected mental capacity later in life.
Similar to folic acid, iodine fortification has also been made mandatory in bread. Iodised salt, eggs, meat, dairy, seafood and kelp are also sources of iodine. Despite that, surveys of pregnant Australian women have found that many still are at risk of iodine deficiency. In such cases, women may need to supplement with 150mcg iodine daily throughout preconception planning and pregnancy.
Iron deficiency is well known to cause anaemia. During pregnancy, iron demands increases, but supplementation is not routinely recommended for healthy women without a history of anaemia.
Red meat, green vegetables and whole grains are good sources of iron. Iron absorption can also be increased by pairing with vitamin C-rich foods such as citrus fruits. In contrast, tannins in tea and some minerals like calcium can reduce the absorption of iron when consumed together.
Although Australia is known for its sunshine, vitamin D deficiency is unfortunately not uncommon. It is estimated that more than 30% of adult Australians have a mild, moderate or even severe deficiency, which leads to bone and joint problems.
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) recommends supplementation with 10mcg (400IU) of vitamin D3 daily as part of a pregnancy multivitamin if the woman is unlikely to achieve the adequate daily intake of 5mcg. For example, women receiving limited sun exposure due to having darker skin, spending daylight hours indoors, or applying heavy sunscreen may benefit from supplementation.
Apart from the aforementioned, there are many other nutrients that are important for pregnancy. However, this does not mean that supplements are always beneficial. In fact, daily vitamin A supplement has been associated with congenital malformations and daily vitamin C associated with preterm birth.
It is always important to aim for adequate nutrition through whole foods first and only turn to supplementation when there is a good reason to do so, as indicated by your healthcare provider.
For more information regarding preconception planning, you can contact Melbourne-based fertility specialist and gynaecologist, Dr Alex Polyakov here.