L’asfissia fetale intrapartum: studio osservazionale analitico presso l’Azienda Ospedaliero- universitaria “Maggiore della carità” di Novara

ABSTRACT Foetal asphyxia is an unpredictable foetal clinical condition caused by an acute or chronic decrease of maternal and foetal placental gas exchanges, characterized by hypoxaemia and hypercapnia, which can induce hypoxic-ischemic encephalopathy, cerebral palsy or death of the newborn. Foetal asphyxia poses great physiopathological uncertainty but often, in courtrooms, professional negligence is attributed as a cause. This hypothesis has led, in many Western countries, to a defensive behaviour by doctors and midwives, through the increasing use of both elective and/or precautionary caesarean section procedures, and the resulting increase in maternal mortality and morbidity. The purpose of this study is to identify possible concomitant risk factors which are potentially predisposing to the occurrence of a foetal asphyxia with consequences at birth, within the University Hospital "Maggiore della carità" in Novara. Materials and Methods A retrospective analytical observational study has been conducted at the University Hospital "Maggiore della carità" in Novara. All registered cases of foetal asphyxia with consequences at birth from January 1st 2010 to October 31st 2015 have been identified. The group of cases has been compared to a control group, composed by the same number of birth events, in which foetal asphyxia has not been registered, obtained through a randomized sample. Inclusion criteria involve: Single pregnancy Gestational age between 37 and 41 weeks + 3 days, calculated on the basis of the first day of the last menstruation Foetus in vertex presentation Spontaneous or induced labour Spontaneous or operative vaginal delivery or caesarean section Normal cardiotocographic tracing, at the time of mother's admission to the ward (according to the criteria of the International Federation of Gynaecology and Obstetrics (FIGO) 2015 guidelines) Exclusion criteria involve: Foetuses afflicted with malformations, genetic and chromosomal abnormalities diagnosed during pregnancy or during hospitalization of the newborn. Caesarean sections performed without labour Administration of general anaesthesia or opioids to the mother before giving birth The source data is made up of maternal and neonatal medical records, obstetric and neonatal hospital discharge summaries and birth assistance certificates. Pre-gestational, gestational, intrapartum and organisational clinical variables have been considered and analysed. Variables were analysed using Fischer test, U Mann Withmann test and logistic regression. The association probability was estimated by the odds ratio with a confidence interval of 95%. The alpha level of 0.05 was considered significant. Results Given 162 cases of neonatal asphyxia and 162 controls, asphyxia resulted associated with: age> 35 years (OR 3.37; CI 95% 1.95-5.81), p 0.000; non-European ethnic group (OR 1.77; CI 95% 1.02-3.06), p0.041; nulliparity (OR 1.56; CI 95% 1.02-2.47), p 0.050; BMI ≥35 (OR 4.03; CI 95% 2.46-6.59), p0.000; medically assisted procreation operations (OR 13.91; CI 95% 3.22-59.93), p0.000; thrombophilias (OR 3.20; CI 95% 1.13-9.03), p 0.028; pre-existing diabetes before pregnancy (OR 4.70; CI 95% 1.1-22.15,) p0.05; smoke >6 cigarettes a day (OR 14.50; CI 95% 3.37-63.36) p0,0000; preeclampsia p <0.0001; oligohydramnios (OR 6.21; CI 95% 3.01-12.81), p0.000; vaginal bleeding during pregnancy p 0.002; vaginal infections (OR 4.34; CI 95% 2.41-7.80), p0.000; urinary infection (OR 6.90, CI 95% 2.81-16.96), p0.000; chorioamnionitis (OR 9.47; CI 95% 1.18-75.64), p0.034; amniotic fluid stained with meconium (OR 6.33; CI 95%, 2.97-13.50), p0.000; labour duration <3 hours (OR 5.09; CI 95% 1.99-13.01), p0.001, labour duration >12 hours (OR 4.86; CI 95% 2.30-10.26), p0.0000; epidural analgesia (OR 1.91; CI 95% 1.22-2.97), p0.004; variable and late decelerations at CTG (OR 28.40; CI 95% 15.13-53.31), p0.000; silent foetal heart tracing (OR 48.60; CI 95% 5.98-394.71), p0.000; emergency operative vaginal delivery and caesarean section for CTG abnormalities in foetal heart rate, respectively (OR 6:57; CI 95%, 2.58-16.73), p0.000; (OR 4.92; 2.70-8.96), p0.000; expulsion period duration >2 hours (OR 6.16; CI 95% 1.88-20.12), p0.003; duration <30 minutes (OR 4.25; CI 95% 10.51 58.73), p0.000; labour in gynaecological position (OR 33.88; CI 95%12.24-93.78), p0.000; labour in seated/crouched position (OR 4.05;1.59-10.31), p0.003; lacked attendance in one-to-one modality (OR 4.58; CI 95% 2.84-7.39), p0.000; birth in the night (OR 2.27; CI 95% 1.44-3.56), p0.000, high volume of daily activity (OR 2.59; CI 95% 1.54-4.36), p0.000; newborn's weight < 2500 gr OR 1.38(CI 95% 1.782.44), p0.004; obstetrician's experience >15 years (OR1.99; CI 95% 1.23-3.20), p0.005. Multivariariate analysis drew attention to the contemporary influence of: pathological CTG, lacked attendance in one-to-one modality, urinary and vaginal infections, >12 hours duration of labour, birth in the night. Conclusions This study has shown that the occurrence of birth asphyxia is associated with the simultaneous or sequential action of many factors, each of which facilitates increase of risk likelihood. Some of the identified variables are not modifiable. Women over age 35, with pregnancies achieved by assisted reproduction techniques, afflicted with hypertension, preeclampsia, diabetes or thrombophilia, subjected to induction and/or pharmacological acceleration of labour, especially if in epidural analgesia are exposed to a greater risk of foetal asphyxia. It might be useful if research committed to create a tool that allows assigning a risk score based on predisposing factors. This would allow addressing induction and surveillance protocols specific to a particular target of women whose labour is at medium-high risk.