Study population and sample recruitment
Eligible patients will be enrolled during the ultrasound scan of the first trimester combined screening test for aneuploidies (11-13+6 weeks), according to the following inclusion criteria: singleton viable pregnancy undergoing prenatal screening, gestational age between 11 and 13+6 weeks of pregnancy, further confirmed by a crown-rump length (CRL) measurement of 45-84 mm, and signed written informed consent. Language barrier, any known maternal disease or required chronic therapy, oocyte donation pregnancy, as well as fetal congenital anomalies and aneuploidies confirmed at birth, represent the exclusion criteria.
Figure 1 summarizes the study step points with maternal, fetal and neonatal data collection.
At enrollment, all women will fill a general questionnaire covering details on age, pregestational body mass index (BMI), ethnicity, mode of conception, lifestyle habits, family and personal history. A modified version of the nutritional checklist developed by the International Federation of Gynecology and Obstetrics (FIGO) in 2015 will be used to provide a 0 to 10 nutritional score measuring the adherence to a healthy diet and lifestyle, as presented in Figure 2. Additional adaptations of the checklist are based on the Italian guidelines on maternal nutrition during pregnancy, including one additional question on the consumption of iodized salt and the modified recommended intake of fruit and vegetables to five portions per day. In detail, the FIGO Nutrition Checklist consists of four sections covering 1. specific dietary requirements (e.g. diet or allergy), 2. BMI calculation, 3. diet quality, and 4. specific micronutrients deficiency queries (e.g. folic acid), thus giving the healthcare providers the possibility to collect baseline information on maternal nutritional status and to promote conversations about nutrition during pregnancy. A one-point score is calculated in case of affirmative answer for: consumption of meat 2–3 times per week, fruit and vegetables at least 5 times per day, fish 1–2 times per week, dairy products daily, whole cereals at least once per day, sweet and snacks less than 5 times per weeks, first trimester hemoglobin concentrations higher than 11 g/L, folic acid supplementation, use of iodized salt, and sun exposure at least 10–15 min per day. The questionnaire provides a final calculation of a 0 to 10 score, as the sum of single question scores.
As required by the first trimester combined screening test, biochemical parameters and fetal ultrasound parameters will be collected. Biochemical parameters, including serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (free β-HCG), will be obtained from one venous blood sample collected at 10 weeks of gestation, by using a solid-phase two-site sequential chemiluminescent immunometric assay (BRAHMS Kryptor, Hennigsdorf, Germany). All ultrasound measurements will be performed by a Fetal Medicine Foundation certified sonographer according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guidelines. In addition to parameters required for the combined screening test and including crown-rump length (CRL), nuchal translucency (NT), and biparietal diameter (BPD), transabdominal measurements of Doppler velocimetry of uterine arteries (UA) and two-dimensional placental volume will be performed. Transabdominal UA Doppler velocimetry is achieved identifying the artery along the uterine body from a midsagittal section and moving laterally to the paracervical vascular plexus (12). The two-dimensional estimated placental volume (EPV) measurement will be performed according to the formula proposed by Sonek J. et al, by acquiring assessment of placental width (measuring the distance among placental edges, perpendicular to surface of placenta), height (as distance from uteroplacental interface to line used to measure width) and thickness (as distance from uteroplacental interface to fetal surface of placenta) (13).
As required by national guidelines of low risk pregnancy care, second (20-22 weeks) and third (30-32 weeks) trimester ultrasound data of fetal biometry (BPD, HC, AC, FL) and Doppler velocimetry (uterine arteries doppler, fetal umbilical artery Doppler, fetal middle cerebral artery Doppler) will be obtained from medical records. Data on delivery outcomes, including gestational age, delivery mode, blood loss, neonatal data and placental weight will be recorded from medical registry or phone interview.
The recruitment process and follow up will last 30 months.