Study results

Food supplement use during pregnancy differs from recommendations

A diet with variety will meet most additional nutritional needs during pregnancy. Some food supplements, such as vitamin D and folic acid supplements, are recommended in most countries to be used during pregnancy to secure sufficient nutrient intake. However, excessive use of food supplements at higher than recommended doses might also, in some cases, have adverse effects on the health of both the mother and the foetus.

A questionnaire survey conducted in international collaboration between the four countries of Finland, Italy, the United Kingdom (UK), and Poland assessed food supplement use among pregnant women, women’s attitudes towards food supplements, and their understanding of food supplement needs and possible health impacts during pregnancy. The data were collected using an online questionnaire. (Koivuniemi et al. 2022a)

Majority of the women who participated in the study used food supplements, and the number of simultaneously used products varied between one and nine. Particularly in Finland, it was common to use more than one product concurrently – as many as a fifth of the supplement-users used more than three products at the same time. The use of food supplements was most common in Finland and least common in Italy. A prenatal multivitamin product was the most used supplement type. First-time mothers and non-smokers used food supplements more likely than women who had given birth before and women who had smoked frequently before the pregnancy.

In Finland, UK, and Poland, the recommended vitamin D supplement was used by most of the supplement users, but e.g. in Finland, only about a half of the vitamin D supplement users used it at the recommended doses and a third of them exceeded the recommended dose. Folic acid supplement, which is recommended to be used during pregnancy, was also used by almost all the women who used food supplements. In Finland, only about a half of the folic acid supplement users used it at the recommended doses during pregnancy, and a third of them exceeded the recommended intake.

Exceeding the recommended food supplement intake was relatively common: in Finland, a third of the pregnant women exceeded the recommended intake of at least one food supplement. Moreover, the daily safe upper intake limit was exceeded in one or more nutrients by a fifth of the food supplement users. In particular, magnesium supplements were used at doses that exceeded the daily safe upper intake in all of the countries.

Vast majority of the participants of the study answered that they knew which food supplements and what doses of supplements they need to consume during pregnancy. Nonetheless, three quarters of the participants thought that multivitamin supplements are generally recommended during pregnancy, although it is not recommended. Majority of the participants knew that folic acid is recommended during pregnancy. Further, slightly over half of the participants in Finland, Poland, and the United Kingdom were aware that vitamin D supplementation is recommended during pregnancy in their home country, whereas in Italy, a third of them mistakenly thought that vitamin D supplement is recommended to be used during pregnancy in Italy.

Although most of the pregnant women in all countries believed that they were aware of the food supplement recommendations, in practice, the recommendations were not always adhered to. In terms of nutrients that are recommended to be used as supplement, the intake was mostly sufficient, but even excessive for a significant proportion of the women. The results show the importance of discussing food supplement use in antenatal care so that the excessive use of food supplements can be addressed when needed. The results also enable enhancement of dietary counselling so that it supports food supplement use that is in accordance to that recommended during pregnancy.