The maternal vitamin D osteoporosis study
hyperparathyroidism, ’, foetal anomalies, Osteoporosis, hypercalciuria, renal stones
HYPERPARATHYROIDISM, METABOLIC BONE DISEASE, OSTEOPOROSIS, EARLY PREGNANCY
The Maternal Vitamin D Osteoporosis Study (MAVIDOS) was a multicentre, double-blind, randomized, placebo-controlled trial of vitamin D supplementation in pregnancy. The primary outcome was neonatal bone mass. A detailed description of the study methodsWomen attending one of three United Kingdom (UK) hospitals [University Hospital Southampton National Health Service (NHS) Foundation Trust, Southampton, UK (latitude 50.9° North); Oxford University Hospitals NHS Foundation Trust, Oxford, UK (latitude 51.8° North); Sheffield Hospitals NHS Trust (University of Sheffield), Sheffield, UK (latitude 53.4° North)] for early pregnancy ultrasound screening (11–14 weeks’ gestation) between 6 October 2008 and 11 February 2014 were invited to participate in the study. Gestational age was determined using the date of last menstrual period (LMP) and with first trimester foetal ultrasonographic crown-rump length measurement used if >7 days’ discrepancy between LMP and scan dates, uncertain LMP date, irregular cycles or hormonal contraception-use within last 3 months. Inclusion criteria were age over 18 years, singleton pregnancy and gestational age ˂17 weeks based on LMP and ultrasound measurements. Women with known metabolic bone disease, renal stones, hyperparathyroidism or hypercalciuria, those taking medication known to interfere with foetal growth, foetal anomalies on ultrasonography and women already using >400 IU/day vitamin D supplementation were excluded. A screening blood sample was obtained and analysed on the local NHS platform [all three laboratories (Southampton, Oxford and Sheffield) participate in the Vitamin D External Quality Assessment Scheme (DEQAS) vitamin D quality assurance system (