Each mother-child pair contributing to the study provides maternal and umbilical cord blood as well as placental tissue and maternal urine. After delivery, the mother fills out an extensive questionnaire regarding in-house environment, education, occupancy, health status, stress, smoking and life-style habits. Three days after delivery, the Neonatal Behavioral Assessment Scale (NBAS) is completed and the neonates blood pressure is recorded.
At age 4
After a prospective follow-up, children aged 4 to 6 years are re-invited to participate.
Blood pressure is measured repeatedly using a fully automated upper-arm blood-pressure monitor with a special sized cuff for children. Information about growth, length, weight and waist circumference is also collected.
Heart rate is monitored during the clinical examination via the small, portable wireless Zephyr Biopatch that is attached to the participant’s chest by two standard ECG-electrodes. Different parameters of heart rate variability (e.g. SDNN) are extracted based on these measurements.
Retinal photography provides a non-invasive, in vivo, method to characterize the human microvasculature since retinal vessels are 60–300 µm in diameter. For each participant, the fundus of both right and left eye is photographed in a darkened room using a Canon 45° 6.3-megapixel digital nonmydriatic camera. Features of the retinal blood vessels, including vessel caliber and tortuosity, are extracted using image analysis software.
Carotid ultrasound allows for a non-invasive assessment of carotid intima-media thickness and arterial stiffness parameters based on automatic boundary detection software (MyLabOne, Esoate Benelux) with a 13 MHz probe.
Cognitive performance of the study participants is assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) Research Suite, investigating measures for (sustained) attention, reaction time, visual memory and executive function.
Bone density is determined in a non-invasive, radiation-free manner based on the quantification of axial ultrasound transmission determined at the lower forearm, using the BeamMed Sunlight MiniOmni.
Buccal cells are collected using SK-2 Isohelix buccal swabs (Cell Projects Ltd, UK). Urine samples are also collected in metal-free containers. If both the participating child and the accompanying adult consent, a blood sample is also collected.
Length and height are measured at the time of the examination and growth data from birth onwards are recorded. The parents fill out an extensive questionnaire, inquiring about life-style habits (including a food frequency questionnaire), health status, stress, and in-house environment such as smoking status of the parents. Furthermore, the child’s behavior is assessed through a Strengths and Difficulties Questionnaire (SDQ), filled out by the mother.