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Objectives:The study aims to investigate: 1) whether first trimester head volume can be measured reliably as an early predictor for fetal head growth using a virtual reality technique; 2) the influence of maternal peri-conception characteristics on head growth trajectories. Methods: In the Rotterdam peri-conception cohort healthy singleton pregnancies were enrolled and weekly 3D ultrasound (3DUS) examinations between 6 +0 and 12 +6 weeks gestational age (GA) were performed. Using a virtual reality system crown-rump length (CRL), embryonic volume (EV), head volume, biparietal diameter (BPD) and occipitofrontal diameter (OFD) were measured longitudinally and head circumference (HC) was calculated from BPD and OFD. Reference-curves and regression lines were created investigating associations between HV and HV/EV and GA, CRL and EV. Z-scores were calculated to correlate embryonic HV and HC with fetal HC obtained from second trimester anomaly scans. Linear mixed models were estimated to model associations between maternal characteristics and embryonic HV. Results: 303 (73%) 3DUS images of 149 pregnancies were eligible for embryonic head measurements (ICC intra-/interobserver >0.99). Moderate correlation was assessed between embryonic HC and fetal HC (ρ = 0.617, p < 0.01) and also embryonic HV with fetal HC (ρ = 0.660, p < 0.01). Linear mixed models demonstrated a significant negative association between maternal peri-conceptional smoking and HV (β = −0.0276 mm 3 95%CI = −0.0066;-0.2373 p < 0.05) and significant positive associations between maternal age (β = 0.0043 mm 3 95%CI = 0.0008;0.0399 p = 0.01), peri-conceptional maternal use of alcohol (β = 0.0141 mm 3 95%CI = 0.0033;0.0261 p < 0.01) and HV. Conclusions: Reference curves of embryonic HV growth can be created reliably using a virtual reality technique, which also enable the establishment of small deviations in embryonic HV growth trajectories by peri-conceptional exposures. The implications of these findings need further investigation. OP20.03Correlation of ultrasonographic and pathophysiologic measurements of umbilical and placental vessels in normal and growth restricted fetuses Objectives: The exact development of intrauterine growth restriction (IUGR) is not yet fully understood. Placental insufficiency, reduced delivery of oxygen/nutrients to the fetus can result altered fetoplacental circulation. We compared the ultrasonographic measurements of placental and umbilical cord vessels to their reactivity to vasoactive agents. Methods: Cases with IUGR due to placental malfunction were selected for case group and compared to healthy AGA controls. Placental 3D power Doppler vascularisation index (VI), flow index (FI) and vascularisation flow index (VFI) was measured by VOCAL technique. We performed tissue bath experiment on these vessels. Results: The VI mean was 3.23 (p = 0.04) in IUGR and 6.20 in controls, the FI mean was 33.62 and 34.40 and the VFI mean was 1.34 and 2.15 respectively. In isolated tissue bath experiment, vasopressine did not alter the spontan...

AimTo investigate whether ATP-sensitive potassium (KATP) channels modulate the tocolytic effect of β2-AR agonists (ritodrine and salmeterol) in early-pregnant (day 6) and late-pregnant (day 22) rat uterus in vitro, in order to examine the relation between the KATP channel sulphonylurea-binding regulatory subunit (SUR) expression and pharmacological reactivity of β2-AR agonists.MethodsThe tocolytic effects of ritodrine and salmeterol (10-10-10-5 M) on spontaneous rhythmic contractions were investigated cumulatively, alone, or in the presence of the KATP channel blocker glibenclamide (10-6 M) and the KATP channel opener pinacidil (10-9-10-7 M) after 5-min preincubation.Resultsβ2-AR agonist induced myometrial relaxation was inhibited by glibenclamide and enhanced by pinacidil on day 6, when SUR1 expression levels were high. Neither glibenclamide nor pinacidil mediated tocolytic effect was measured on day 22.ConclusionLow expression of the KATP channels at the end of gestation may facilitate enhanced excitability and contractility in the rat myometrium. The combination of a betamimetic and a KATP channel opener will therefore not be of therapeutic relevance in the treatment of preterm delivery.

The results indicate that umbilical vessels might not have oxytocin or vasopressin receptors. The pathomorphologic and flowmetric differences could be the causes of small birth weight.

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