Vitamin D and the risk of dystocia: A case-control study.

Christine Rohr Thomsen,Mohammed Rohi Khalil,Lars Rejnmark,Ioanna Milidou,Niels Uldbjerg,Lone Hvidman,Salvatore Andrea Mastrolia

doi:10.1371/journal.pone.0240406

Christine Rohr Thomsen, Mohammed Rohi Khalil + Show 5 more

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https://doi.org/10.1371/journal.pone.0240406

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Abstract

Dystocia is one of the most common causes of cesarean section in nulliparous women. Studies have described the presence of vitamin D receptors in the myometrium, but it is still unclear whether vitamin D affects the contractility of the smooth muscles. We therefore aimed to determine the association between the vitamin D serum level at labor and the risk of dystocia. We conducted a case-control study between January 2012 and June 2017. Cases were primiparous women, with spontaneous onset of labor, who gave birth by cesarean section due to dystocia. Controls were primiparous women with a spontaneous vaginal delivery. We included 60 women (30 cases and 30 controls) in the analysis. The differences between cases and controls were assessed using chi-squared test for categorical variables and two-sample t-test or unequal t-test for continuous variables, as appropriate, after evaluation of whether they followed the normal distributions. The mean serum 25-hydroxyvitamin D concentrations were 53.1nmol/l (95%CI; 45.2 to 60.9) among cases and 69.9nmol/l (95%CI; 57.5 to 82.4) among controls (P = 0.02). The mean plasma parathyroid hormone levels were 2.25 pmol/l and 2.38, respectively (P = 0.57). Even though 78% of all women reported taking a minimum of 10μg/day of vitamin D throughout pregnancy, 43% had vitamin D insufficiency, defined as serum 25-hydroxyvitamin D levels below 50nmol/l. In a Danish group of women having a cesarean section due to dystocia, we found decreased vitamin D levels.

Highlights

Vitamin D insufficiency during pregnancy is a worldwide public health problem [1, 2]
Data Availability Statement: The data underlying the results presented in the study are submitted to the The Danish National Archive, where it will be available upon request
In a Danish group of women having a cesarean section due to dystocia, we found decreased vitamin D levels

Summary

Introduction

Vitamin D insufficiency during pregnancy is a worldwide public health problem [1, 2]. In a Danish study, one third of all pregnant women had a serum 25-hydroxyvitamin D (S-25OHD) below 50nmol/ l [3], which is the cut-off level for insufficiency according to the Danish National Board of Health [4]. This insufficiency is presumably due to the lack of dermal vitamin D production from October to April, resulting from the insignificant UVB radiation in the sunlight during this period. Maternal vitamin D insufficiency may be associated with several adverse pregnancy complications, including preeclampsia [5,6,7] and gestational diabetes mellitus (GDM) [8] It is still unknown whether vitamin D affects the contractility of the myometrium. The concentration of calcium, largely determined by the level of vitamin D, is of importance for labor contractions [9, 13]

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