Diet in pregnancy

Illustration photoThe Norwegian Mother and Child Cohort Study (MoBa) can give us information about the importance of diet in pregnancy. Is health authority advice on diet and supplements being followed? Do we need to give health information in other formats? In week 22 of pregnancy, women gave detailed information about their diet. Here we will describe what we have learnt from MoBa about diet in pregnancy.

Folic acid protects against spina bifida so supplements are recommended for women planning to conceive and in the first three months of pregnancy. It is too late to start when pregnancy is confirmed because the crucial period is between four to eight weeks after conception. Of the MoBa participants, only one in three pregnant women took folic acid supplements during the first three months of pregnancy and only one in ten began as early as recommended.

Six out of ten mothers in MoBa took cod liver oil or other fish oils, yet the average intake of vitamin D, iron and iodine was lower than recommended.

Can diet reduce the risk of pre-eclampsia?

Five per cent of first-time mothers develop pre-eclampsia in pregnancy. We already know that maternal obesity and diabetes increases the risk but we know little about the role of diet. For first-time mothers in MoBa there was a 26 per cent lower risk for pre-eclampsia with a high vitamin D intake. The vitamin D content in the normal diet did not vary between mothers with and without the condition; the difference came from vitamin D supplement use. Pregnant women with a high intake of vegetables, fruit and vegetable oils had a 28 per cent lower risk of pre-eclampsia than those who ate a lot of processed meats, sugary drinks and snacks. With daily or weekly intake of probiotic milk products (Biola and Cultura), pre-eclampsia occurred less often, especially the more severe form. In summary, we can therefore say that vitamin D, vegetables, fruits, vegetable oils and probiotic milk products protect against pre-eclampsia among MoBa participants.

Does diet affect birth weight?

In Norway, malnutrition in pregnancy with adverse consequences for the child is not a big problem, but other dietary factors may also play a role in foetal growth. Previously, researchers had found that low birth weight occurred more frequently when the mother did not take folic acid supplements. This is largely disproved by MoBa; the average birth weight was not lower in pregnant women who did not take folic acid and had lower concentrations in the blood compared with others. However, mothers in MoBa with a high seafood intake, especially lean fish, seem to bear larger children than others.

What about premature birth? Mothers who gave birth at term had a higher intake of probiotic milk products than those born spontaneously before 37 weeks. Those who ate fish at least twice a week had a lower risk of giving birth prematurely. However, there was no difference in preterm birth in pregnant women with a so-called Mediterranean diet in relation to other diets.

Where and how?

Can we trust our memory about what we ate in the last few weeks? Initially, this was a key issue, and the questionnaire had to be validated. One of the strengths of MoBa is that we can measure a number of substances in blood and urine samples, and thus ensure that the dietary form provides precise enough information. Markers were studied in 119 pregnant women who had maintained an accurate dietary log for four days. Most of us ingest iodine through dairy products, and therefore it can be measured in urine as a control of milk and cheese intake. Similarly, intake of fruit, vegetables and fish products are measurable. Even though memory is never completely reliable, the questionnaire is quite accurate and provides useful information about the diet of the participants.

The aim of MoBa is to determine the causes of disease and health. Data from more than 100 000 pregnancies have provided information about various factors that can help us understand why disease occurs early in life. So far, more than 30 articles about diet in MoBa have been published in international journals. Many researchers are working with this information, and the children in the study are now being followed towards adulthood.

MoBa has provided new and exciting discoveries that will have implications for health in future generations. When multiple studies are available and the results are clear, the advice and measures from health authorities can adapt based on new knowledge. MoBa will continue to build a solid knowledge foundation for good health, where a good diet is a key element.