What is a significant effect of maternal aspirin use during pregnancy?

Maternal aspirin use during pregnancy can lead to a significant effect known as the premature closure of the ductus arteriosus. The ductus arteriosus is a critical vessel that connects the pulmonary artery to the aorta in a developing fetus, allowing most of the blood to bypass the non-functioning lungs. Aspirin can inhibit the synthesis of prostaglandins, which are essential for keeping the ductus arteriosus open. If aspirin is taken in the later stages of pregnancy, particularly in the third trimester, there is a risk that it could lead to an early closure of this vessel. This premature closure can result in serious complications for the fetus, including cardiovascular issues and increased pressure in the heart and lungs.

The other options presented do not accurately describe the associated effects of maternal aspirin use. Increased fetal weight is often not correlated with aspirin use and could be influenced by numerous other factors. Maternal aspirin is not typically associated with better fetal health outcomes, especially in the context of premature closure of the ductus arteriosus. While aspirin has been studied for its potential benefits in certain conditions, it does not generally reduce the risk of preterm birth effectively. Thus, the important consideration of premature closure makes the correct answer particularly relevant.