RESEARCH – February 2017

Serum level of vitamin D in the second pregnancy trimester has an impact on pregnancy outcome and maternal health

Authors: Kristine Roos, Aili Tagoma, Anne Kirss, Raivo Uibo, Kadri Haller-Kikkatalo

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Backround. Vitamin D affects the expression of more than 200 genes and has a major role in several physiological processes. Our body needs vitamin D throughout life, however, it plays an especially crucial role during pregnancy when it affects the health of both the future mother and the newborn. Vitamin D deficiency has become a worldwide problem in recent time.

Purpose. To detect vitamin D values in blood serum in Estonian women during pregnancy, to study the factors influencing vitamin D level and to estimate the effect of low vitamin D level on the health of mother and child.

Methods. The anamnestic and clinical data of 118 healthy pregnant women, recruited from the Women’s Clinic of Tartu University Hospital, were analysed during the second trimester of pregnancy and in the postnatal period. Their serum vitamin D values were determined by the chemoluminescenceimmune method. Linear and logistic regressioon analyses adjusted for confounders were used for statistical analyses.

Results. The mean level of serum vitamiin D was detected at 55.0 ± 22.8 nmol/ l , remaining under the reference value (75 nmol/l) in 79.7 (71.1–86.3)% of the subjects, while 17.8 (11.6–26.1)% of subjects presente with vitamin D deficiency (≤30 nmol/l). The level of serum vitamin D depended on the calendar month and on the woman’s body mass index preceding pregnancy. Low gestational levels of vitamin D were associated with greater weight gain during pregnancy, necessity to intervene with labour, birth of a macrosomal child, lower Apgar grade, deficiency of infant’s postnatal adaption and postpartum difference in blood pressure between the arms of mother (more than 10 mmHg).

Conclusions. Low level of vitamin D is a common problem among Estonian women during pregnancy; being impaired by timing of pregnancy during calendar months with low solaar intensity index and adiposity before pregnancy. Low vitamin D level is hazardous to the course of pregnancy and to the futuure health of mother and child. Since Estonia is located at the latitude of low intensity sunlight, solar exposure during summertime is not sufficient to maintain required vitamiin D level for the rest of the year. Therefore, we encourage general practitioners, but most certainly gynaecologists, to determine serum vitamin D level especially in pregnant women and to supplement vitamin D in case of need. However, the data available today strongly recommends the prophylactic dose of vitamin D supplementation to be 70–80 IU/kg per day.