Hypothesis : Vitamin D serum concentration is decreased in the first trimester in pregnant women who will develop preeclampsia in the second or third trimester compare to a control group Primary purpose : To determine the vitamin D status in the first trimester in a large population of french pregnant women in order to evaluate the importance of the vitamin D deficiency in France and correlate this deficiency with preeclampsia

Primary purpose : To compare the vitamin D (25OHD) status, in the first trimester, in a group of patients with preeclampsia and a group of pregnant women without preeclampsia.

Secondary purpose : (i)To compare the vitamin D status in the third trimester in a group of patients with preeclampsia and a group of pregnant women without preeclampsia. (ii) To evaluate the deficit un vitamin D in a population of pregnant women in the parisian area. (iii) To evaluate the calcemia of the newborns after maternal systematic oral intake of vitamin D 100000U at 28 weeks Methodology : Multicenter (6 centers), Cohort, Nested case-control study Protocol : 4500 patients will be recruited. A blood sample will be performed : in the first trimester (11-14 weeks), in the third trimester (28-40 weeks), and cord blood. For each patient with preeclampsia, 4 controls will be taken from the cohort and matched by parity, race/ethnicity, maternal age, season, BMI. The serum concentration of 25OHD will be measured in all samples.A dosage of 25OHD will be performed in 1000 women from the initial cohort in order to calculate the prevalence of vitamin D deficiency.

Inclusion Criteria:

• Pregnant woman
• First trimester
• Singleton
• Affiliated to Social security policy
• Woman who gave informed consent

Exclusion Criteria:

• Hypercalcemia (>2.65 mmol/l) or any other phosphocalcic disease
• Hypertension (>140/90) from the first trimester
• Renal insufficiency (creatinine > 120µmol/l)
• Bone disease (osteogenesis imperfecta…)
• Lithium therapy
• Bowel malabsorption
• Kidney stones

Teh vitamin D status will be measured in a large population of french pregnant women (in the first trimester) in order to evaluate the importance of the vitamin D deficency in France and correlate this deficiency with preeclampsia