What does it mean when embryonic development is delayed?

Embryonic developmental delay, medically termed fetal intrauterine growth restriction, refers to a condition in which the growth rate of the fetus inside the uterus falls below the normal range, resulting in a birth weight lower than two standard deviations or below the 10th percentile of the average weight for the gestational age. This may be caused by genetic factors, maternal diseases such as hypertension and diabetes, placental dysfunction, multiple pregnancies, infections, malnutrition, environmental factors such as smoking, and other similar influences.

Maternal factors are a major contributor; insufficient nutritional intake during pregnancy and complications such as diabetes and hypertension can all affect normal embryonic development. Furthermore, fetal factors cannot be overlooked, as chromosomal abnormalities or insufficient secretion of growth hormones can directly impact its endocrine and metabolic functions, leading to growth retardation. Additionally, placental and umbilical cord abnormalities, such as umbilical cords that are too long, too short, or too thin, may lead to insufficient placental blood supply, thus affecting the fetus's nutritional supply. Advanced maternal age and external environmental factors, such as exposure to chemicals and radiation, may also negatively impact embryonic development.