Cathrine Ebbing

Fetal cardiac output, distribution to the placenta and impact of placental compromise.

Intrauterine growth restriction is a common clinical problem, but the underlying hemodynamic changes are not well known. Our aim was to determine the normal distribution of fetal cardiac output to the placenta during the second half of pregnancy, and to assess the changes imposed by growth restriction with various degrees of placental compromise.

Middle cerebral artery blood flow velocities and pulsatility index and the cerebroplacental pulsatility ratio: longitudinal reference ranges and terms for serial measurements

To establish reference ranges suitable for serial assessments of the fetal middle cerebral (MCA) and umbilical (UA) artery blood flow velocities, pulsatility index (PI) and cerebroplacental pulsatility ratio and to provide terms for calculating conditional reference intervals suitable for individual serial measurements.

Ductus venosus shunting in growth-restricted fetuses and the effect of umbilical circulatory compromise

To determine the degree of ductus venosus (DV) shunting in fetuses with intrauterine growth restriction (IUGR) and the effect of various degrees of umbilical circulatory compromise.

Prevalence, Risk Factors and Outcomes of Velamentous and Marginal Cord Insertions: A Population-Based Study of 634,741 Pregnancies

Objectives To determine the prevalence of, and risk factors for anomalous insertions of the umbilical cord, and the risk for adverse outcomes of these pregnancies. Design Population-based registry study. Setting Medical Birth Registry of Norway 1999–2009. Population All births (gestational age >16 weeks to <45 weeks) in Norway (623,478 singletons and 11,263 pairs of twins). Methods Descriptive statistics and odds ratios (ORs) for risk factors and adverse outcomes based on logistic regressions adjusted for confounders. Main outcome measures Velamentous or marginal cord insertion. Abruption of the placenta, placenta praevia, pre-eclampsia, preterm birth, operative delivery, low Apgar score, transferral to neonatal intensive care unit (NICU), malformations, birthweight, and perinatal death. Results The prevalence of abnormal cord insertion was 7.8% (1.5% velamentous, 6.3% marginal) in singleton pregnancies and 16.9% (6% velamentous, 10.9% marginal) in twins. The two conditions shared risk factors; twin gestation and pregnancies conceived with the aid of assisted reproductive technology were the most important, while bleeding in pregnancy, advanced maternal age, maternal chronic disease, female foetus and previous pregnancy with anomalous cord insertion were other risk factors. Velamentous and marginal insertion was associated with an increased risk of adverse outcomes such as placenta praevia (OR = 3.7, (95% CI = 3.1–4.6)), and placental abruption (OR = 2.6, (95% CI = 2.1–3.2)). The risk of pre-eclampsia, preterm birth and delivery by acute caesarean was doubled, as was the risk of low Apgar score, transferral to NICU, low birthweight and malformations. For velamentous insertion the risk of perinatal death at term was tripled, OR = 3.3 (95% CI = 2.5–4.3). Conclusion The prevalence of velamentous and marginal insertions of the umbilical cord was 7.8% in singletons and 16.9% in twin gestations, with marginal insertion being more common than velamentous. The conditions were associated with common risk factors and an increased risk of adverse perinatal outcomes; these risks were greater for velamentous than for marginal insertion.

Hepatic Artery Hemodynamics Suggest Operation of a Buffer Response in the Human Fetus

After birth, the hepatic artery buffer response helps to maintain liver perfusion. Here, the authors establish a Doppler technique to measure fetal hepatic artery flow velocity and test the hypothesis that the buffer response also operates prenatally. Women with low-risk pregnancies were recruited to a longitudinal study (N = 161). Measurement techniques and reference ranges for hepatic artery velocities and pulsatility index (PI) were established. Ductus venosus peak velocity (VDVps) represented the portocaval pressure gradient, and umbilical venous flow (QUV) represented portal flow. Reference ranges were established for the more accessible left hepatic artery branch. Hepatic artery PI was lower in fetuses with VDVps <10th centile (P < .05) and in those with QUV <10th centile ( P < .0001). Conversely, hepatic artery PI was higher in those with QUV >90th centile (P < .0001). The authors establish a method for measuring fetal hepatic arterial blood velocity, provide reference ranges, and show that the hepatic artery buffer response operates prenatally.

Redistribution pattern of fetal liver circulation in intrauterine growth restriction

Objective. Fetal liver blood supply is an important determinant of fetal growth and adaptation. Most fetal liver blood supply is from the umbilical vein, but the portal vein contributes 14–20% and studies of low‐risk pregnancies suggest the splanchnic arteries are also involved in the homeostasis of fetal liver perfusion. Here we determine the circulatory pattern of the fetal liver in intrauterine growth restriction (IUGR). Design. Cross‐sectional study. Population. Thirty‐one IUGR fetuses (estimated fetal weight <5th centile). Methods. Pulsatility index (PI) measurements of the umbilical, middle cerebral, splenic, hepatic, and superior mesenteric arteries were compared with a reference population and related to umbilical venous flow, umbilico‐caval pressure gradient (assessed by ductus venosus peak velocity) and venous distribution within the liver (assessed by flow velocity in the left portal vein). Results. Thirteen of 31 IUGR fetuses had umbilical artery PI > 97.5 centile and 13 showed a middle cerebral artery brain‐sparing pattern (PI Z‐score < − 2). In IUGR, umbilical venous flow was lower and less umbilical blood was distributed to the right liver lobe, while the umbilico‐caval pressure gradient was kept normal. The hepatic and splenic arteries, but not the superior mesenteric artery, had low PI compared with the reference population. Conclusions. IUGR fetuses with increased or normal umbilical artery PI maintained venous perfusion pressure to the liver while distributing less umbilical blood to the right liver lobe. They showed regional splanchnic arterial redistribution with low splenic and hepatic artery PI, implying increased portal venous flow and direct arterial contribution to hepatic perfusion, respectively.

Fetal hemodynamic development in macrosomic growth

To determine the venous and arterial hemodynamics underlying macrosomic fetal growth.

Fetal celiac and splenic artery flow velocity and pulsatility index: longitudinal reference ranges and evidence for vasodilation at a low portocaval pressure gradient

To establish longitudinal reference ranges for the fetal celiac and splenic arteries flow velocity and pulsatility index (PI), and to determine their hemodynamic relationship to venous liver perfusion and distribution and to other essential arteries.

Risk factors for recurrence of hypertensive disorders of pregnancy, a population based cohort study.

Hypertensive disorders of pregnancy (HDP) tend to recur from one pregnancy to the next. The aims of the study were to assess the recurrence risk according to type of HDP defined by gestational age at birth and to examine whether recurrence is associated with the following additional risk factors for HDP: maternal age, smoking, inter‐delivery interval, diabetes, body mass index, and fetal growth restriction, and to assess temporal trends in these associations.

Velamentous or marginal cord insertion and the risk of spontaneous preterm birth, prelabor rupture of the membranes, and anomalous cord length, a population based study

Anomalous cord insertion is associated with increased risk of adverse maternal and perinatal outcome. Our aim was to study whether anomalous cord insertion is associated with prelabor rupture of membranes (PROM), preterm PROM (pPROM), long or short umbilical cord, and time trend of spontaneous preterm birth (SPTB) and anomalous cord insertion.