Folate and vitamin B12 deficiencies detected in pregnant women in the Camp de Tarragona area

Research by the Pere Virgili Health Research Institute (IISPV) and the Rovira i Virgili University (URV) has studied the supplementation patterns and levels of these vitamins in pregnant women, the lack of which is a risk factor for the health of mothers and children

The Preventive Medicine and Biostatistics Unit of the IISPV and the URV has carried out a study to determine the supplementation patterns of pregnant women in Camp de Tarragona and their folate and vitamin B12 levels. After studying 831 pregnancies, they determined that only 36% of women follow the recommendations for folic acid supplementation and detected low levels of folate and vitamin B12 in almost half of them at some stage of their pregnancy. Deficiencies in these vitamins, essential for foetal development, can lead to miscarriage, malformations and other health problems in mothers and children.

Folic acid and vitamin B12 are essential nutrients for a successful pregnancy and optimal maternal and infant health. Folic acid is a man-made supplement containing folates, i.e. vitamin B9. Folates are found in green leafy vegetables, legumes, nuts and some meats and are crucial for the proper functioning of the nervous system, cardiovascular system and cell division processes, which are critical during pregnancy. Vitamin B12, or cobalamin, also plays a key role in the functioning of the nervous system and in DNA synthesis, among others. Both are vital for the entire foetal development process, from conception to birth. A deficiency of either of these vitamins is considered a risk factor for maternal and infant health, which can cause miscarriage, severe foetal malformations, deficiency and anaemias in late pregnancy and adverse infant health.

‘Although pregnant women are advised to take folic acid supplements, they often do not receive this advice until their first prenatal check-up,’ says Michelle Murphy, a researcher in the URV’s Department of Basic Medical Sciences and co-author of this research. Prenatal care guidelines include the recommendation to take 400µg daily from one month before conception until the end of the first trimester of pregnancy. However, the first medical visit of pregnancy may in some cases take place weeks or even months after conception. ‘We assume that this factor prevents many women from being aware of the importance of these supplements before they become pregnant,’ says Murphy.

The Reus-Tarragona Birth Cohort (RTBC) study is the largest investigation of folate and B12 levels in pregnant women carried out in a high-income country. The research team monitored the levels of these vitamins in 831 women, who followed their pregnancies at the Hospital Sant Joan de Reus and the Hospital Joan XXIII de Tarragona, from the early stages of pregnancy until birth. The research therefore collected data on the women’s supplementation patterns and measured levels of B12 and folic acid at five points during pregnancy.

There are two ways to determine a person’s folate levels: by measuring plasma folates, i.e. the level of B9 in the blood; or by measuring erythrocyte folates, which indicate the amount of this vitamin that has reached the red blood cells. In the first case, the plasma folate level is susceptible to fluctuation, due to dietary changes, within hours. In the second case, erythrocyte folate levels give a better idea of the long-term presence of B9 in the body. The study revealed that 47% of the pregnant women in the sample had erythrocyte folate levels below the threshold recommended by the WHO to prevent abnormalities in foetal development. By measuring plasma folate, the research team identified very low levels of this vitamin in 5% of the women at the beginning of pregnancy, and in 25% at the end of pregnancy.

In addition, the researchers found that more than 16% of the women in the sample had the variant form of a genetic polymorphism associated with increased folic acid requirements. This genetic peculiarity, common in southern Europe, makes women – and also men – more likely to have low reserves of this vitamin so important for the gestation process. ‘Without alarming anyone, the message is that we cannot take folic acid supplementation lightly,’ says Murphy. At the same time, the results of the study reveal that although 80 per cent of the women in the sample planned pregnancy, only 36 per cent took folic acid supplements before conception.

As for vitamin B12, deficiencies were detected in 7% of pregnant women at the first screening. This proportion increased drastically in subsequent records, reaching 44% of women with low cobalamin levels at the end of pregnancy. ‘Historically, the explanation for low B12 levels in pregnant women has been justified by the high intake of this vitamin in the formation of the placenta and foetus,’ explains Murphy. However, the URV researcher points out that this explanation only reflects 35% of cases with low levels of this vitamin at the end of pregnancy. The researcher warns of the false sense of security that exists in countries that adhere to the Mediterranean diet: ‘We have shown that there are widespread deficiencies in this vitamin’.

Vitamin supplementation in pregnancy is so important to prevent foetal developmental abnormalities that in more than 80 countries around the world, governments are making it mandatory to fortify flour with folic acid to ensure that all women are provided with folic acid. European countries have not implemented this policy, but neither have they stepped up their campaigns to raise awareness among women of childbearing age of the importance of these supplements. Michelle Murphy points out that more research is needed in this area and stresses the importance of communication campaigns to raise awareness of the importance of supplementation in pregnant women: ‘They are not perfect, because they never reach everyone, but they have been shown to work in other parts of the world.

Referencia: Santos-Calderón LA, Caballé-Busquets P, Ramos-Rodríguez C, Grifoll C, Rojas-Gómez A, Ballesteros M, Ueland PM, Murphy MM. Folate and cobalamin status indicators, modulators, interactions and reference ranges from early pregnancy until birth. The Reus-Tarragona Birth Cohort. Am J Clin Nutr 2024; Sep 24: DOI: 10.1016/j.ajcnut.2024.09.015