The objective of the study is, if an early oral glucose tolerance test combined with maternal history, condition and multiple biomarker analysis can be used to detect gestational diabetes mellitus in the first trimester (12-14 weeks of gestation).

It is the investigators' aim to prospectively examine an extended form of the current 1st trimester screening test for the detection of foetal aneuploidy, in order to ascertain whether this can also be used for the detection of patients at-risk for gestational diabetes mellitus. For this purpose the investigators will include a combination of new markers in a multiplex bio-array manner in conjunction with an early oral glucose tolerance test. A nested case-control proteomic analysis will be performed in a retrospective manner at the completion of this study in order to develop more specific biomarker panels.

The primary outcome will be development of gestational diabetes mellitus in the second or third trimester.

The secondary endpoints are the delivery outcome, neonatal morbidity, neonatal mortality, maternal morbidity and costs.

Inclusion Criteria:

• Healthy singleton pregnancies
• Women at least 18 years old and not under guardianship

Exclusion Criteria:

• Maternal diseases like hypertension, diabetes mellitus and chronic disease, known infection like hepatitis or human immunodeficiency virus
• Maternal history of hypertensive diseases in previous pregnancy and now under prophylactic acetylsalicylate treatment
• Foetal genetic, chromosomal or intervention-requiring morphologic abnormalities

Pregnant Women