Data obtained by the researchers
Anthropometric data include body height, weight and fat percentage. The body length is measured at the first measuring moment, using a microtoise to the nearest 0.5 cm. The body weight is measured at each clinical measuring moment to the nearest 0.1 kg with indoor clothing but without shoes, using the local calibrated balance. The pre-operative weight in non-pregnant subjects, together with the subjects’ length, is used to calculate the pre-operative BMI (kg/m2). Pregnant subjects were asked for their pre-pregnancy weight (self-administered) to calculate the pre-pregnancy BMI (kg/m2). The total gestational weight gain is defined as the weight at time of birth minus the pre-pregnancy weight. The body fat percentage is only measured in non-pregnant subjects, using the local Bio-Electrical Impedance Analysis (BIA).
The medical history of the participant is questioned at baseline (T0), together with the type, date and location of bariatric surgery. The medical history relates to the subject’s previous medical conditions and diseases. The specific type of procedure is questioned (LAGB, SG, RYGB and BPD/DS) in order to distinguish between the restrictive, purely malabsorptive or combined types of procedures. The date of the surgery is used to calculate the interval period between surgery and conception.
Follow-up by a dietitian, possible complications, co-morbidities and the use of medication or nutritional supplements are monitored at each pre- and postoperative and pre- and postnatal follow-up consultation.
The
nutritional status of each participant is assessed by biochemical parameters in venous blood (Table
3). This screening includes assessments which are covered by the National Institute for Sickness and Disability Insurance (NISDI) as well as specific additional assessments not being covered by the NISDI but covered by study budget. The assessments covered by the NISDI are clinically relevant in the context of an optimal follow-up of the subject after bariatric surgery or during pregnancy. The additional assessments are not included in the standard care, but are considered being relevant as study parameter. The serum blood samples should optimally be collected in a fasting condition. The obesity clinics are responsible for the pre- and postoperative assessments, the obstetric units for the preconception, pre- and postnatal assessments. The nutritional status of the newborn is determined by biochemical parameters in venous cord blood, collected at the delivery wards. These serum markers are analyzed in the local hospitals, all equipped with certified laboratories with validated ring tests.
Table 3
Nutritional assessment
Obesity clinic | *haematology (haemoglobin, haematocrit and red blood cell count: mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration) *coagulation (prothrombin time, activated partial thromboplastin time) *total protein, albumin *vitamin B-12, folate serum *25-hydroxy vitamin D *iron, transferrin, tranferrin saturation, ferritin *calcium, zinc *glucose metabolism (glucose) | *folate red blood cells *vitamin A, E, B-1, magnesium |
Obstetrics and gynaecology | *haematology (haemoglobin, haematocrit and red blood cell count: mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration) *coagulation (prothrombin time, activated partial thromboplastin time) *total protein, albumin *vitamin B-12, folate serum and red blood cells *iron, transferrin, tranferrin saturation, ferritin *calcium, zinc, magnesium *glucose metabolism (glucose) | *coagulation factors, vitamin K1 *vitamin A, vitamin E, vitamin B-1 *25-hydroxy vitamin D |
Veneus cord blood | | *haematology (haemoglobin, haematocrit and red blood cell count: mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration) *coagulation (prothrombin time, activated partial thromboplastin time, vitamin K1) *vitamin B-12 and folate serum and red blood cells *vitamin A and 25-hydroxy vitamin D |
The assessment of the
fasting glucose level at the beginning and 24 weeks of pregnancy is also included for the pregnant subjects as an alternative for the oral glucose tolerance test (OGTT), which is the standard diagnostic test for GDM [
34]. It is well known that a glucose overload in patients with a malabsorptive or mixed procedure surges insulin secretion, probably causing reactive hypoglycemia [
22]. The use of an OGTT can therefore be contra-indicated for the diagnosis of GDM in subjects with a history of bariatric surgery. Subjects who report to be sensitive for severe dumping symptoms are screened for GDM by a first and second trimester assessment of the fasting glucose level. When the fasting glucose levels appear to be indicative for a disturbed glucose metabolism, glucose home monitoring will be initiated around 24–28 weeks of gestation. This includes fasting and two hours postprandial glucose monitoring for seven days using a glucose monitoring kit.
Clinical parameters of the pregnant subjects are measured by the researcher in every pregnancy trimester (T6-T8). These parameters include gestational age (based on the crown-rump length assessed by fetal ultrasound), blood pressure and proteinuria (>300 mg/24 h). The diagnosis of pregnancy-induced hypertension is defined according to the guidelines of the International Society for the Study of Hypertension in Pregnancy:
de novo blood pressure ≥ 140/90 mmHg appearing after 20 weeks of gestation. Pre-eclampsia is defined as the presence of pregnancy-induced hypertension or chronic hypertension in combination with proteinuria [
35]. All possible complications during pregnancy, delivery and postpartum period are prospectively recorded in the patient’s study file. Next, outcomes from the fetal ultrasounds are summarized (quality of ultrasound, biparietal diameter, abdominal circumference, femur length, head circumference, frontal occipital diameter, estimated fetal weight, amniotic fluid index, pulsatility index of A. Uterina, Umbilicalis and Cerebri Media). In case of a laparoscopic adjustable gastric band, management of the band (closing – opening) is evaluated. The gestational age in weeks, use of combined spinal epidural anesthesia, fetal position and mode of delivery (vaginal, cesarean section, instrumental delivery) are collected at birth (T9). Characteristics from the newborn, including birth weight and length, Apgar scores, admission to the neonatal intensive care unit and clinical problems are reported (T9). Early postpartum data include information about breastfeeding practices (exclusive breast feeding, artificial feeding, difficulties, duration).
Clinical parameters being reported 6 weeks and 6 months after delivery include body weight, the intake of dietary supplements or medication and any clinical problems or complications occurring.
Self-administered data by the participants
Demographic data are collected at baseline (T0). Date of birth, nationality, ethnicity of the participant and first-line family members, marital status, family situation, educational level and occupational data are questioned.
The obstetric history of the participant is also collected at baseline (T0). This includes the number of previous pregnancies, the need for a fertility treatment, the final outcome of a previous pregnancy (miscarriage, abortion, ectopic pregnancy, born alive) and gestational age and birth weight of the baby.
Participants who are included before or after surgery are asked for their intention of becoming pregnant and the period in which they plan to do this.
A study-specific developed questionnaire is used to evaluate the menstrual cycle, contraceptive use and sexual activity. The length of the menstrual cycle, the cycles per year, pattern and duration of bleedings and the presence of amenorrhea or oligomenorrhea are questioned. The need for a fertility treatment and the method of the treatment is asked. The used contraceptive is also of interest, including the exact type, dose and problems with usage. The frequency of sexual intercourse and any related problems are recorded. These questionnaires are based on the standard clinical assessments at the gynecology clinic of UZ Leuven.
Lifestyle is being investigated using questionnaires about dietary intake, physical activity, alcohol, tobacco use and sleeping habits, all collected via the online system. The
actual diet is examined on three non-consecutive days (including one day of the weekend) by use of a 3-day estimated dietary record, using an online semi-structured diary. Information on the type and amount of foods consumed is collected through an open entry format. Each day of the food record was divided into breakfast, lunch, dinner and morning, afternoon and late-evening snacks. Subjects who donate breast milk samples are additionally asked to complete a Food Frequency Questionnaire (FFQ) in the immediate postpartum (day 3–4) and 6 weeks postpartum. This FFQ is inspired on pre-existing FFQ’s already used in the Belgian population groups (e.g. [
36]) and on the general accepted FFQ development guidelines [
37]. The FFQ allows to monitor trends in nutrient intake and dietary pattern (=
usual intake). The level of
physical activity is measured using a Dutch and French version of the Kaiser Physical Activity Survey (KPAS). This survey measures different domains of physical activity including 1) household and family care, 2) professional activities, 3) daily life activities and 4) sports and exercise. The KPAS is validated for both pregnant and non-pregnant women [
38,
39]. A Dutch and French version of the Alcohol Abuse Disorder Identification Test (AUDIT-C) includes three short questions on
alcohol use and is considered to be a practical and validated screening test to detect alcohol abuse and dependency [
40]. S
moking is questioned, and for smokers the amount of cigarettes or other tobacco products per day is recorded. Finally, sleep duration during the week and week-end is questioned.
The intake of dietary supplements is also questioned via an online questionnaire (brand name, dosage, posology, start and end date).
The
quality of life is determined using the Moorehead-Ardelt Quality of Life Questionnaire II (M-A QoLQII) [
41]. This validated questionnaire is part of the Bariatric Analysis and Reporting Outcome System (BAROS) [
42]. BAROS is a scoring system to evaluate quality of life (M-A QoLQII), weight loss and improvement of co-morbidities. The M-A-QoLQII is translated in Dutch by two experts [
43] and in French by the research team.
Evaluation of
psychosocial health focuses on anxiety and depression. A Dutch validated and a French non-validated version of the American State-Trait Anxiety Inventory evaluates the two concepts of ‘state and trait anxiety’ [
44]. Two separate questionnaires include 20 items or statements on which answers can be given on an intensity (state anxiety) or frequency (trait anxiety) scale. A Dutch and French version of the Edinburgh Depression Scale (EDS), a validated 10-item scale, is used to measure depressive feelings during the pre- and postnatal period [
45‐
47].
Finally, a structured Dutch questionnaire developed by Guelinckx et al. (2011), also translated into French by the researchers, is used six months after birth (T11) to evaluate the intention, initiation and duration of breastfeeding and reasons to quit breastfeeding.