A recent study conducted by the Child Psychiatry Research Center at the University of Turku has unveiled concerning findings about the vitamin D levels of pregnant immigrant women in Finland. Unlike previous assumptions, early pregnancy vitamin D levels in mothers with immigrant backgrounds, whose children have been diagnosed with disorders in learning, language, or motor skills, do not differ significantly from those of Finnish mothers.

However, the study highlighted a stark contrast in the average vitamin D levels between immigrant mothers and their Finnish counterparts, with immigrant women showing alarmingly low levels.

The research aimed to explore the connection between low vitamin D levels during pregnancy among immigrants and the development of neurodevelopmental disorders in children. This inquiry stemmed from observations that children from immigrant families tend to exhibit a higher prevalence of neurodevelopmental disorders compared to children from the Finnish majority population, the reasons for which remain unclear.

"We know from previous research that the vitamin D levels among immigrants are lower than those of the Finnish population. We wanted to investigate if low vitamin D levels during pregnancy could partly explain the higher incidence of diagnoses in learning, language, and motor skills within this group," explained Dr. Bianca Arrhenius, the lead author of the study.

Contrary to expectations, the study found no direct link between low vitamin D levels and developmental disorders. Vitamin D levels were uniformly low among immigrant mothers, regardless of whether their children had been diagnosed with the aforementioned developmental issues or not.

"Nevertheless, the average vitamin D levels among immigrant mothers were alarmingly low compared to the Finnish majority population. The average levels among immigrant mothers were around 25 nmol/liter, whereas levels considered sufficient are generally over 50 nmol/liter," Arrhenius noted.

The study also revealed that following a change in vitamin D supplementation recommendations in 2003 and the fortification of certain foods with vitamin D, the levels among the Finnish population have slightly increased, whereas the levels among immigrants remained low.

"This finding underscores the importance of preventive services, such as maternity clinics, in informing expectant mothers, especially those from immigrant backgrounds, about the significance of taking vitamin D supplements," said Professor André Sourander, director of the Child Psychiatry Research Center.

Although the study did not establish a connection between low prenatal vitamin D levels and developmental disorders in children, vitamin D plays crucial roles in the development of the fetus's skeleton and brain.

The study utilized data from the Finnish Maternity Cohort (FMC) national maternity clinic serum collection, linking it with other registries. It included 542 children of immigrant mothers diagnosed with developmental disorders in learning, language, or motor skills, comparing their mothers' prenatal vitamin D levels with those of 542 Finnish counterparts and 443 immigrant mothers whose children did not have these diagnoses. The children studied were all born in Finland between 1996 and 2006.

The findings were published in the PLOS ONE journal on February 29, 2024, under the title "Vitamin D levels of pregnant immigrant women and developmental disorders of language, learning and coordination in offspring."