Because the maternal prenatal hospital misestimated the fetal weight, and the estimated weight differed by 900 grams from the actual birth weight, Ms. Zhang mistakenly chose to give birth on her own and encountered dystocia, which ultimately resulted in infertility. The child\’s left upper arm moved after birth, which constituted an eighth-level injury. Disabled. How is fetal weight estimated? What is the standard weight of the fetus in the mother\’s belly?