Smoking and alcohol during pregnancy: effects on fetal and child health. The role of oxidative stress and possible dysregulation of neurotrophins

Introduction: the aim of this study was to evaluate fetal and neonatal effects induced by smoking and alcohol during pregnancy. The role of oxidative stress and possible dysregulation of neurotrophins were also investigated. Material and methods: after written informed consent, we recruited full-term pregnant patients. Exclusion criteria: age ˂20 or ˃40 years; gestational age ˂37+0 or >42+0; multiple pregnancies; placental pathologies; medically assisted procreation; maternal psychiatric, neurological and/or autoimmune diseases. Questionnaires were used to investigate smoking and alcohol habits. Ultrasound was performed to evaluate fetal weight, amniotic fluid index, and maternal-fetal Doppler velocimetry. At the time of delivery, we collected a tuft of maternal hair (nicotine, cotinine, ethyl glucuronide-EtG), maternal venous blood and cord blood (reactive oxygen species-ROS, neurotrophins). Placental weight and neonatal data were also collected. Phase I: determination of nicotine, cotinine and EtG on maternal keratin matrix with the gas chromatography-mass spectrometry technique. Positive test for nicotine if > 0.16 ng/mg, cotinine if > 0.07 ng/mg and EtG if > 20 pg/mg. Phase II: Free Oxygen Radicals Test (FORT) and Free Oxygen Radical Defense (FORD) test were used to asses circulating ROS. A condition of oxidative stress was indicated by FORT > 330 Fort Unit and FORD test < 1.08 Trolox equivalents. Neurotrophins were evaluated on maternal venous blood and cord blood using ELISA. The descriptive statistical analyses were performed using ANOVA software. Results: 119 pregnant patients were enrolled (n=62 were tested for smoking and n=57 for alcohol). Twenty-six patients (42%) out of 62 were active smokers, 18 (29%) were passive smokers, and the remaining 18 (29%) were non-smokers. Three patients (5%) out of 57 resulted alcoholic consumers. The mean neonatal weight was on the 51^ percentile for non-smoker patients, on the 49^ percentile for passive smokers and on the 8^ percentile for active smokers. Comparing active smokers and non-smokers, mean neonatal weight and mean placental weight were significantly lower for active smokers (p=0.0001 and p=0.0060, respectively). The neonatal weight was on the 1^-2^ percentile for alcohol abusers. Considering two subgroups (n=10 non-smokers and n=10 active smokers) for ROS determination, Student’s-t test (95% CI, p<0.05) showed a statistically significant higher oxidative stress in the blood of smoking patients (FORT p<0.0001; FORD p=0.0156). In cord blood the differences were not statistically significant with a condition of oxidative defense, probably induced by the mother. Moreover, active smoking mothers exhibited significantly lower BDNF levels compared to non-smokers (p = 0.001), whereas their children had significantly higher BDNF levels (p = 0.001). Conclusions: fetal growth restriction was confirmed in the group of active smokers and in patients with alcohol abuse. Oxidative stress is higher in smoking patients than in non-smokers. However, in cord blood FORT and FORD were negative in all cases, suggesting a protective mechanism in utero. Higher BDNF levels in the offspring of smoking mothers also suggested potential compensatory mechanisms.