E. Ryo, N. Unno, T. Nagasaka, Y. Taketani
Changes in the size of maternal inferior vena cava during pregnancy
Aims: To investigate the changes in the size of maternal
inferior vena cava (IVC) during normal pregnancy.
Methods: The diameter and the area of IVC were measured
in 32 non-pregnant and 214 pregnant women by
ultrasonography. They were measured not only in the
supine but also in the complete left lateral position when
gestation was over 16 weeks.
Results: IVC in the 4–7 weeks pregnant group was larger
than that in the non-pregnant group, and it decreased as
gestation progressed during an early stage of pregnancy.
After 16 weeks gestation, it demonstrated no change, at
least for depending on the periods when the mother was
in the supine position. On the contrary, they increased
with the gestational progress as for the maternal left lateral
position.
Conclusions: The size of IVC at an early stage of pregnancy
is enlarged, suggesting an underfilling state of
arterial circulation. In the second and third trimesters, it
is stationary when the mother is supine. In the left lateral
position, it increases as the gestation progresses, reflecting
blood volume expansion during pregnancy.
Journal of Perinatal Medicine, Walter de Gruyter
Print ISSN: 1619-3997
Volume: 32, 07/2004
Pages: 327 - 331
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