RESUMO
BACKGROUND: In the past, a lot of researches used one-time lead level in umbilical cord blood at birth for investigations,however, one-time lead level in umbilical cord blood at birth can not represent lead caused cumu lative injury to neonatal nervous system during the whole period of preg nancy. Lead in meconium is mainly from digestive juice secreted by fetal alimentary tract, exfoliative epithelia from neonatal intestinal tract and am niotic fluid and sebum cutaneum swallowed by fetus, which is excreted from the very start of pregnancy to 24 hours after birth of neonates and re flects the lead deposit in neonatal intestinal tract during the whole period of pregnancy. OBJECTIVE: To explore the relationship between neurobehavioral devel opment in neonates with intrauterine exposure to lead at low level and the lead level in umbilical cord blood (CBPb) and meconium (MPb). DESIGN: Take lead levels in umbilical cord blood and meconium as neonatal intrauterine exposure indicators and scores of neonatal neurobe havioral development as effect indicators, and descriptive analysis is used to evaluate the correlativity. SETTING: Wuhan University of Science and Technology; Laboratory of Occupation Disease and Epidemiology, Tongji Medical College, Huazhong University of Science and Technology; Wuhan First Metallurgical Con struction Company Hospital for Workers and Staff. PARTICIPANTS: A total of 103 cases of full-term and healthy neonates were selected as objects of observation. The neonates were born in Depart ment of Gynecology and Obstetrics, Wuhan First Metallurgical Constrction Company Hospital, Qingshan District of New Industrial District of Wuhan from January to October 1999. Their parents were agreed to participate in the study and filled in the questionnaire, and provided neonatal meconium and performed neonatal tests on schedule. METHODS: ① Collection and assay of sample: 5 mL umbilical cord blood were collected and reserved in refrigerator at -4 ℃. Meconium with in 24 hours after birth, with dry weight between 5 to 10 g was collected, the lead levels in umbilical cord blood and meconium were assayed with the method of graphite furnace atomic absorption spectroscopy. ② Group ing: The neonates were divided into two groups with high and low-exposure to lead based on the cutoff value of CBPb of 0.483 μmol/L and MPb of 127.78 mg/kg. ③ Neonatal neurobehavioral development examination: Neonatal neurobehavioral development examination method was used for examination 3 days before delivery. Meanwhile, self-designed questionnaire was used to conduct a survey in puerperas. MAIN OUTCOME MEASURES: ① Lead levels in neonatal umbilical cord blood and meconium. ② Scores of neurobehavioral development of neonates with different lead levels of umbilical cord blood and meconium. RESULTS: All the 103 cases of neonates entered results analysis. ①There was significant difference only in scores of neonatal behavioral neurological assessment (NBNA) and biological visual and auditory orientation reaction (BVAOR)between groups with high and low-exposure to lead in umbilical cord blood (P ＜ 0.05). However, there was no rank correlativity between lead level in umbilical cord blood and scores of NBNA,non-biological auditory orientation reaction (NBAOR), non-biological visual orientation reaction (NBVOR) and biological visual and auditory orientation reaction (NBVOR). ②here was significant difference in scores of NBNA,NBAOR, NBVOR and BVAOR between groups with high and low-exposure to lead in meconium (P ＜ 0.05-0.01). The lead level in meconium clearly correlated reversely with scores of NBNA, NBVOR and BVAOR.CONCLUSION: Lead level in meconium is more sensitively related to the scores of neonatal neurobehavioral development, which could be used as indicator for lead deposit in the fetal body during the period of pregnancy.