Research shows that pregnancy after obesity surgery has benefits, but also potential drawbacks. The main benefits are a reduced risk of gestational diabetes, high birth weight or high blood pressure during pregnancy. On the other hand, there is an increased risk of low birth weight and premature birth.

After obesity surgery, there is an increased risk of marked fluctuations in sugar levels and a more frequent occurrence of low sugars (hypoglycemia). There is increasing evidence that these abnormalities also occur during pregnancy after obesity surgery. We hypothesize that these specific abnormalities contribute to the increased risk of low birth weight.

During the GLORIA study, sugar levels will be measured at different times during pregnancy. These measurements will be made via a glucose sensor that continuously measures the sugar levels under the skin. Blood samples will also be taken from the mother and via the umbilical cord at delivery to detect possible abnormalities in the metabolism. The growth and body composition of the babies will be closely monitored by ultrasound, during routine obstetrics consultations.

In this study, half of all participants will have undergone a gastric bypass or sleeve gastrectomy, the other half will never have had obesity surgery, but will have a similar weight at the start of the study (control group). The number of estimated participants in the study is 95 in each group. In order to be able to evaluate the sugar values in a standardized way, both groups will use a blind glucose sensor at 4 times during pregnancy for 10 days each. A glucose sensor continuously measures the sugar levels subcutaneously. A blind glucose sensor means that the measured sugar values cannot be seen by the study participant. Normal pregnancy monitoring continues while using the blind sensor.

Who can participate in the GLORIA study?

Participants:

• are between 18-45 years
• are pregnant with a singleton pregnancy with a gestational age of up to 11 weeks and 6 days.
• speak Dutch, French or English and have access to e-mail
• have
  • undergone a sleeve gastrectomy or gastric bypass procedure
  • or participate in the control group provided they have never had obesity surgery before

Who cannot participate in the GLORIA study?

One cannot participate if:

• there is pre-existing diabetes mellitus, or if one is taking medication that can interfere with glucose metabolism
• there is a multiple pregnancy
• there was alternative obesity surgery : such as gastric band or gastric balloon placement, endoscopic sleeve gastrectomy, mini gastric bypass, Scopinaro procedure, etc.
• there is a physical or psychological illness that prevents the study from being carried out (according to the advice of the treating physician).

The study starts early in pregnancy (one can participate up to 12 weeks of pregnancy) and ends after delivery. At the start of the study, a bioimpedance analysis will be performed. During pregnancy, in line with the normal routine, ultrasounds will be performed and the growth of the baby will be measured precisely.

At 4 times during the pregnancy (before 12 weeks, around 20 weeks, around 26 weeks and around 32 weeks) a blinded glucose sensor will be placed at the upper arm (or abdomen).

Blood samples will be taken at 4 times during pregnancy to detect possible deficiencies in vitamins and minerals (micronutrients) and to check glucose metabolism. These blood draws are also in line with the routine follow-up. These blood samples will be saved for further analysis of the metabolism (metabolomics). Questionnaires will be taken from all participants at these times.

At birth, the skinfold of the baby will be measured and the outcomes of pregnancy and delivery will be registered.