All of the following are true statements concerning fetal circulation except

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In fetal life the circulation is built to maximize delivery of oxygenated blood to the fetus while bypassing the nonfunctional lungs. The lungs are filled with fluid and pulmonary vascular resistance is high, so only a small amount of blood goes to the lungs; most systemic blood comes from the left ventricle via the aorta, while a ductus arteriosus shunts some blood from the pulmonary artery into the aorta to support systemic flow.

The right ventricle tends to be thicker than the left in the fetus because it sustains a larger workload against the high pulmonary resistance, and the right heart handles a substantial portion of the fetal cardiac output since much venous return is routed through the right-sided side before reaching the left heart or the systemic circulation. The pulmonary artery branches are underdeveloped in utero because the lungs are not yet ventilated, so the pulmonary vascular bed remains narrow and offers high resistance.

The statement that blood enters the systemic circulation only at the ductus arteriosus level is not true. Systemic blood is primarily supplied by the left ventricle through the aorta; the ductus arteriosus provides an additional route by shunting blood from the pulmonary artery to the aorta, bypassing the lungs but it is not the sole entry point for systemic circulation.