2.1. Study Design
GDM
GDM
This is a prospective unicentric interventional analysis of the “San Carlos GDM prevention study”. This study began in 2015 and its follow-up is ongoing. The study has been undertaken at the Hospital Clínico San Carlos, providing medical assistance to 463.833 patients in Madrid, Spain. During pregnancy, women are followed up from the 8th to 12th gestational week (GW) when the first ultrasound is performed. Between the 24th and 28th GW, the 75 g oral glucose tolerance test (OGTT) is carried out for detection of GDM. Both the nursing staff and the obstetricians give medical recommendations and nutritional advice to pregnant women from the onset of pregnancy. Since 2012, IADPSG criteria have been applied for the diagnosis of GDM [The first study (Study 1), whose participants have been included in the current one, was a randomized controlled trial (RCT), with women allocated before the 12th GW into the control group (CG) and the intervention group (IG). A MedDiet pattern was recommended: women of the IG were urged to increase the consumption of extra virgin olive oil (EVOO) >40 mL/day and to consume a handful of pistachios daily, with both foods provided at no cost. Conversely, CG women were encouraged to consume less than 40 mL/day of EVOO and to not eat nuts more than three times a week. The second study (Study 2) consisted in evaluating the effects of the MedDiet implemented early in pregnancy on a single group based on routine clinical practice (real world). Women from Study 2 were encouraged to follow the same nutritional indications as the IG from the RCT of Study 1 but were not provided EVOO and pistachios at no cost and were free to choose the nuts they preferred. The third study (Study 3) was an RCT in which women with a body mass index (BMI) ≥ 25 kg/mAfter randomization of participants at the 8th–10th GW, three visits during gestation were undertaken. The first visit was made between the 12th and 14th GW, the second between the 20th and 24th, and the third between the 36th and 38th GW. After delivery, a 3-month visit was made, in which a 60 min motivational interview was carried out to encourage the subjects to continue with the nutritional and lifestyle habits acquired during pregnancy. Detailed information on each visit during and after childbirth is displayed in All women belonging to previous studies were invited to attend a follow-up visit 3 years postpartum. Participants made an appointment by phone as well as by email/letter. They were informed of the timing of the follow-up as well as the volunteer character of the analysis. Participants who could not attend were invited to complete questionnaires via email or telephone. However, within this 3-year time period, several women were unable to participate in the monitoring for different reasons (such as having a new gestation during the follow-up, or any health condition or treatment that could result in modifications of analytic values and/or in body composition).