A study by R.R Martin on the relationship between maternal nausea during pregnancy and child behavior problems showed that children whose mothers reported nausea in the middle and late stages of pregnancy had lower sensory thresholds, higher activity levels and emotional intensity in infancy, poorer adherence to tasks at age 5, sloppier completion of homework at age 12, and more attention and learning problems. Analysis of the causes suggested that prolonged nausea and vomiting interfered with maternal nutritional intake and that nutritional deficiencies had a sustained effect on the neurodevelopment of children who underwent after 3 months of pregnancy, leading to later deviations in child neurobehavior. A domestic survey by Wang Yufeng et al. found that poor maternal nutrition during pregnancy, mental frustration, heavy alcohol consumption by the father at the time of maternal conception, maternal X-ray during pregnancy, maternal heart disease; premature or overdue delivery, delivery abnormalities, and asphyxia at birth were higher in problem children than in control children. Yang Yuxia et al. found that noise during pregnancy and perinatal period had the greatest effect on children’s behavior. Lin Yu et al. found that five risk factors, namely perinatal occurrence of obstructed labor, viral flu, hypoxic asphyxia, history of medication, and preterm birth, were associated with autism. The absorption of polychlorinated biphenyls (PCB s) by pregnant or lactating women can lead to early abortion, malformation, and infant toxicity through the placenta or breast milk. The results of studies on the effects of in utero exposure to PCBs on neurobehavioral development of children: ① Shortened gestational age, low birth weight, reduced head circumference, and cognitive memory deficits were associated with high maternal consumption of PCBs-contaminated fish and higher concentrations of PCBs in cord blood; ② IQ test scores, memory, concentration ability, verbal IQ test scores, and reading comprehension ability were negatively associated with cord blood PCBs concentration was negatively correlated; children with high levels of PCBs exposure in cord blood were three times more likely to have a below-average IQ and two times more likely to have reading comprehension skills that were more than two years behind those of normal children. Abnormal length of maternal gestation is the largest biological factor affecting behavioral problems in rural preschool children. Preterm and preterm children had significantly more behavioral problems in preschool than full-term children, and the biological factors that distinguish behavioral problems from those of urban children ranked after family environmental factors. Low weight is also an influential factor in children’s behavior problems. One study showed that low birth weight children had significantly higher total CBCL scores and extraverted behavior at age 6 than controls, i.e., they had more extraverted behavior problems.