Introduction: Increasing evidence indicates that the rate of fetal growth is partly determined already in the first half of pregnancy. A number of authors have reported that if the fetus is smaller than expected at dating, the risk for a small for gestational age fetus increases.
Objectives: To investigate if maternal vascular function in early pregnancy reflects fetal growth in the first trimester.
Methods: Fifty healthy women with singleton viable pregnancies were included in the study that were recorded the ultrasound department of UltraGyn Stockholm, Sweden for ultrasound dating in gestational week 11-14 . Of these, 25 women had their estimated date of delivery postponed ⩾ 7 days at ultrasound dating compared to last menstrual period in gestational week 11-14. As controls 25 women were fetal size were in accordance with the last menstrual period (defined as expected date of delivery moved less than six days) were recruited. The dating examinations were performed by specially trained midwives. To assess gestational age, biparietal diameter was used. Exclusion criteria were the use of oral contraceptives within three months before conception, uncertain date of the last menstrual period, irregular menstrual periods, fetuses that were ⩾ 21 days larger or smaller than expected, and fetal anomalies. Women that smoked were also excluded. Blood pressure was measured in the upper arm in a conventional way. The central blood pressure was calculated with a validated algorithm. Changes in skin microcirculation were measured using laser Doppler fluxmetri (LDF). Both endothelial dependent dilatation using assessment of acetylcholine (Ach) and local warming of skin to 44C for maximum micro vascular hyperaemia (MMH) and non endothelial dilatation using assessment of sodium nitroprusside (SNP) was examined.
Results: Fetuses that were smaller than expected at ultrasound dating compared to last menstrual period at gestational week 11-14, had an increased change in maximum micro vascular hyperaemia (p=0.034). There was no significant correlation between ACh-response (p=0.59) and SNP-response (p=0.23). No differences were seen in blood pressure.
Conclusion: In the first trimester, changes in vascular function might reflect important adaptations that are required to facilitate normal fetal growth. This was highlighted by the findings of a positive correlation between fetal growth at 11-14 weeks gestation and changes in endothelial dependent microcirculation. Vascular function of these women will be followed longitudinally during pregnancy and related to obstetric outcome. If changes in microcirculation in the first trimester correlates to an increased risk for complications such as hypertensive disorders during pregnancy or intrauterine growth restriction this gives new insights into the early phase of these complications.
Copyright © 2012. Published by Elsevier B.V.