Final answer:
To promote diuresis in pregnancy, the recommended position for a woman to lie in is the left lateral position, which reduces pressure on the vena cava and aids kidney function.
Step-by-step explanation:
In pregnancy, the position that is recommended for a woman to lie in to promote diuresis is the left lateral position. This position helps in reducing the pressure of the uterus on the inferior vena cava, which in turn can improve kidney function and increase urine output. In contrast, lying supine, or face up, can lead to the inferior vena cava syndrome in late pregnancy, whereby the enlarged uterus compresses the inferior vena cava and can impede blood flow back to the heart, reducing diuresis. A prone position, lying face down, is generally uncomfortable and impractical in later stages of pregnancy. The right lateral position might not be as effective as the left lateral position in promoting optimal venous return and therefore diuresis in pregnancy.