Relationship between vitamin D status in the first trimester of pregnancy and gestational diabetes mellitus - A nested case-control study.

BACKGROUND & AIMS: Gestational diabetes mellitus (GDM) is one of the most frequent medical complications during pregnancy. It has been associated with many adverse pregnancy, fetal and neonatal outcomes, as well as with an increased risk for mothers and children in the long term. There is a growing interest in vitamin D and its potential role in the development of metabolic disorders. However, the medical literature is not consensual. The aim of this study was to assess the risk of GDM according to vitamin D status during the first trimester. METHODS: This study is a nested case-control study performed from a multicenter prospective observational cohort of pregnant women assessed for 25-hydroxyvitamin D levels (25OHD). Three hundred ninety-three patients were included in the initial cohort. After applying exclusion criteria, a total of 1191 pregnant women were included. Two hundred fifty women with GDM (cases) were matched to 941 women without GDM (controls) for parity, age, body mass index before pregnancy, the season of conception, and phototype. This study was funded by a grant from the "Programme Hospitalier de Recherche Publique 2010". RESULTS: The GDM risk was significantly greater for patients with 25OHD levels <20 ng/mL (OR = 1∙42, 95% CI 1∙06-1∙91; p = 0∙021). However, there was no significant relationship with other thresholds. The study of 25OHD levels with the more precise cutting of 5 units intervals showed a variable relationship with GDM risk, as the risk was low for very low 25OHD levels, increased for moderated levels, decreased for normal levels, and finally increased for higher levels. CONCLUSION: According to our study, there seems to be no linear relationship between GDM and 25OHD levels in the first trimester of pregnancy since GDM risk does not continuously decrease as 25OHD concentrations increase. Our results most probably highlight the absence of an association between 25OHD levels and GDM risk.

Relationship between vitamin D status in pregnancy and the risk for preeclampsia: A nested case-control study.

BACKGROUND & AIMS: Vitamin D is thought to be involved in the pathogenesis of preeclampsia. To evaluate the relationship between vitamin D insufficiency in the first trimester of pregnancy and preeclampsia. METHODS: Nested case-control study (FEPED study) in type 3 obstetrical units. Pregnant women from 10 to 15 WA. For each patient with preeclampsia, 4 controls were selected from the cohort and matched by parity, skin color, maternal age, season and BMI. The main outcome measure was serum 25(OH)D status in the first trimester. RESULTS: 83 cases of preeclampsia were matched with 319 controls. Mean 25(OH)D levels in the first trimester were 20.1 ± 9.3 ng/mL in cases and 22.3 ± 11.1 ng/mL in controls (p = 0.09). The risk for preeclampsia with 25(OH)D level ≥30 ng/mL in the first trimester was decreased, but did not achieve statistical significance (OR, 0.57; 95% CI, 0.30-1.01; p = 0.09). High 25(OH)D during the 3rd trimester was associated with a significantly decreased risk of preeclampsia (OR, 0.43; 95%CI, 0.23-0.80; p = 0.008). When women with 25(OH)D levels <30 ng/mL both in the first and 3rd trimesters ("low-low") were taken as references, OR for preeclampsia was 0.59 (95% CI, 0.31-1.14; p = 0.12) for "low-high" or "high-low" women and 0.34 (95% CI, 0.13-0.86; p = 0.02) for "high-high" women. CONCLUSIONS: No significant association between preeclampsia and vitamin D insufficiency in the first trimester was evidenced. However, women with vitamin D sufficiency during the 3rd trimester and both in the first and 3rd trimesters had a significantly lower risk of preeclampsia.

Vitamin D status during pregnancy and in cord blood in a large prospective French cohort.

BACKGROUND & AIMS: Vitamin D status during pregnancy and in newborns has never been studied in France. This study aims at determining the vitamin D status during the first and third trimesters of pregnancy (T1, T3) and in cord blood (CB) in the middle-north of France. METHODS: We conducted a prospective cohort study in five French centers (latitude 47.22 to 48.86°N). Serum 25(OH)-vitamin D (25(OH)D) concentrations were measured using a radioimmunoassay during T1, T3 and in CB. According to the French guidelines, pregnant women received cholecalciferol, 100,000 IU, in the seventh month. RESULTS: Between April 2012 and July 2014, 2832 women were included, of whom 2803 were analyzed (mean ± SD age: 31.5 ± 5.0 years; phototypes 5-6: 21.8%). Three and 88.6% of participants received supplementation during the month before inclusion and in the seventh month, respectively. At T1, T3, and CB, mean 25(OH)D concentrations were 21.9 ± 10.4, 31.8 ± 11.5, and 17.0 ± 7.2 ng/mL, respectively, and 25(OH)D was <20 ng/mL in 46.5%, 14.0%, and 68.5%, respectively. At T1, body mass index ≥25 kg/m2, dark phototypes, sampling outside summer, and no supplementation before inclusion were independently associated with vitamin D insufficiency (25(OH)D < 20 ng/mL). Women who received cholecalciferol supplementation in month 7 had higher 25(OH)D at T3 than non-supplemented women (32.5 ± 11.4 versus 25.8 ± 11.4 ng/mL, p = <0.001) and marginally higher 25(OH)D in CB (17.2 ± 7.2 versus 15.5 ± 7.1 ng/mL, p = 0.004). CONCLUSIONS: Despite the recommended supplementation, vitamin D insufficiency is frequent during pregnancy and in newborns in France.