Maternal positioning during pregnancy may influence fetal Doppler ultrasound findings, but more studies on this subject are needed, according to a study recently published in Revisto Brasileira de Ginecologia e Obstetricia.
Monitoring fetal health is of critical importance, especially in pregnancies already at risk of complications or diseases like hemolytic disease of the fetus and newborn (HDFN), and this is often accomplished via doppler ultrasounds. They are often used to identify cases of fetal growth restriction and determine if blood flow to the fetus is impeded.
During pregnancy, especially in the later stages (second and third trimesters), the weight of the uterus can press on major blood vessels, especially when a woman lies supine, meaning on her back.
Maternal positioning has been thought to influence blood flow to the fetus. In the supine position, there is a risk that a major vessel, the inferior vena cava, may be compressed. This can adversely affect blood flow to the fetus. It is thus common practice for pregnant women to be gently tilted to the left side to relieve pressure on the inferior vena cava. Due to this, some doctors recommend women avoid sleeping on their backs during the later stages of pregnancy.
Researchers sought to further investigate the role of maternal positioning in influencing fetal outcomes by looking at the findings of existing studies related to this matter. They conducting an online search of relevant papers and identified six studies that explored the relationship between maternal positioning and fetal health.
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The findings of these six papers were mixed. Some indicated that maternal positioning can significantly affect fetal blood flow indices, while others did not. None of the papers provided guidance on the optimal maternal position for ultrasound assessments. There is also a lack of evidence about whether maternal positioning affects Doppler ultrasound findings to the extent that it alters fetal diagnosis.
It is important for doctors to understand how Doppler ultrasound results can be influenced. This allows them to be more proactive in maintaining fetal health during pregnancy by initiating useful interventions as early as possible.
“This review underscores the necessity of conducting additional studies and revising existing guidelines on the influence of maternal position on umbilical and middle cerebral artery Doppler indices . . . as current parameters may be biased,” the study concluded.
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