Which of the following is NOT a potential cause of symmetric growth restriction?

Symmetric growth restriction typically refers to a condition where the fetal growth is proportionate, with a decrease in overall size, affecting both the head and body equally. This form of growth restriction can be attributed to factors that impact fetal development uniformly.

Maternal drug use, congenital infections, and chromosomal abnormalities are all recognized potential causes of symmetric growth restriction. Maternal drug use can alter fetal development due to the effects of toxins or nutrients not being properly metabolized. Congenital infections, such as those caused by cytomegalovirus or rubella, can interfere with normal cellular development and growth. Likewise, chromosomal abnormalities can lead to genetic syndromes that disrupt normal growth patterns, resulting in equal-sized restrictions in the growth of fetal organs.

Increased or excessive exercise has not been substantiated as a direct cause of symmetric growth restriction. While excessive physical activity may lead to other complications during pregnancy, it is less likely to uniformly affect fetal growth compared to the other causes mentioned. Instead, the relationship between maternal activity and fetal growth is complex and may depend on various factors, including the mother's overall health, nutrition, and the extent of exercise performed, making it a less direct contributor to symmetric growth issues.

Thus, excessive exercise is the option that does