Screening for pregnancy complications at 11-13 weeks’ gestation

Syngelaki, Argyro (2015) Screening for pregnancy complications at 11-13 weeks’ gestation. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Background: The current approach to prenatal care, which was established more than 80 years ago, is characterised by a high concentration of visits in the third-trimester of pregnancy which implies that firstly, most complications occur at this late stage of pregnancy and secondly, most adverse outcomes are unpredictable during the first or even the second trimester. Objectives: The objective of this thesis is to provide evidence that most pregnancy complications are predictable as early as 12 weeks’ gestation. The pregnancy complications examined include fetal aneuploidies, fetal structural defects, preeclampsia, preterm birth, gestational diabetes mellitus and fetal macrosomia. Methods: I have critically examined fourteen articles reporting on screening for pregnancy complications at 11-13 weeks’ gestation, where more than 90,000 singleton pregnancies were prospectively assessed at 11-13 weeks’ gestation as part of a routine prenatal visit for screening for trisomy 21. We recorded a series of maternal characteristics and history, measured maternal weight and height, performed a detailed ultrasound examination of the fetus, measured maternal uterine artery Doppler pulsatility index and maternal mean arterial pressure and collected blood for analysis of biomarkers for prospective or retrospective analysis. All data were prospectively entered into our data base as well as the pregnancy outcomes as soon as they became available. Ethical approval was obtained for these studies. Multivariate regression analysis was used to define the contribution of each maternal characteristic and history in predicting each adverse outcome and those with a significant contribution formed an algorithm to estimate the background risk (a priori risk) for each one of these complications. The potential value of biophysical and biochemical markers in improving the performance of the a priori risk in predicting adverse pregnancy outcomes, was evaluated. Results: First trimester effective screening for adverse pregnancy outcomes was provided by a combination of maternal factors and biophysical or biochemical markers. The developed predictive models could correctly identify the vast majority of aneuploidies, early preeclampsia and more than half of the cases of spontaneous preterm birth and gestational diabetes. First trimester prediction of fetal macrosomia was less effective compared with other complications. First trimester examination of fetal anatomy was feasible resulting in a high detection of fetal non-chromosomal defects, including more than half of fetal cardiac defects. Conclusions: Assessment of the mother and fetus at 11-13 weeks’ gestation can provide effective early identification of the high risk group of pregnancies with fetal and maternal adverse outcomes.