This study evaluates effect of the Maternal Obesity and/or the By-pass on the Growth and the Nutritional Balance of the Child.The data stemming from mothers presenting obesity or an overweight during their pregnancy and the data stemming from mothers having had a by-pass will be compared with the data stemming from mothers with a normal BMI (Body Mass Index), considered as a reference group. It's the same for the data stemming from newborn children. The newborn children stemming from groups of obese mothers or in overweight will be compared with the data stemming from mothers belonging to the reference group.

The obesity represents a major problem of public health, not only in terms of inferred morbi-mortality but also in terms of economic responsibility. More than 50 % of the women old enough to procreate and 25 % of the women pregnant in Europe are in overweights or obese women. This rate does not stop increasing with prevalence which doubled in 30 years. The overweight or the maternal obesity expose the mother and the child to a greater risk of morbi-mortality. The nutritional stress to which is exposed the foetus during the pregnancy can even have long-term effects with a risk increased by overweight or obesity at the grown-up age, so participating in the cycle of the obesity (" Developmental Origins of Behaviour, Health, and Disease " (DOBHaD) concept).

The morbid obesity (IMC > 40 kg / m2) concern 1 to 3 % of the pregnant women. The gastric bypass surgery is envisaged in case of morbid obesity when the other treatments failed, with better results on the loss of weight and on the comorbidity associated with the obesity, in comparison with not surgical interventions. Near half of the patients who resort to the gastric bypass surgery are women old enough to procreate. Recent studies however moderated the beneficial effects of such an intervention with in particular a greater risk of intra-uterine delay of growth and possible nutritional deficiencies on the descent. The neonatal evaluation was limited to the clinical evaluation, and no biological evaluation of the vitamin and nutritional deficiencies on the growth of the foetus and the placenta was brought reported.

The placenta regulates the contribution in nutriments and oxygen and participle in the foetal homéostasie. The reactive placentary adaptations to an environment of surnutrition or the undernutrition can pull modifications of setting-up, development, functions of the placenta with genic modifications and épigénétiques. All these modifications intervene in a "critical window" in terms of development and participate in the phenomena of foetal programming.

Our working hypothesis is that the nutritional stress in utero associated with the maternal obesity and/or with the by-pass has a medium and long-term short-term, metabolic and neurodevelopmental nutritional impact on the descent.

Inclusion Criteria:

• For "Gastric Bypass Surgery" arm :

  • Pregnant women having undergone a Gastric bypass surgery before the pregnancy.

• For "Reference group" arm :

  • Pregnant women having a body mass index < 25 kg/m2 at the early pregnancy.

• For "Overweight" arm :

  • Pregnant women having a body mass index 25-30 kg/m2 at the early pregnancy.

• For "Obesity " arm :

  • Pregnant women having a body mass index > 30 kg/m2 at the early pregnancy.

Exclusion Criteria:

• For every arms :

  • Underage women
  • Woman with a multiple pregnancy