The Impact of Antenatal Corticosteroids on the Metabolome of Preterm Newborns: An Untargeted Approach.

We analyzed and compared variations in the urinary metabolome, as well as postnatal clinical outcomes among preterm infants, based on the timing of antenatal corticosteroid (ACS) administration in response to preterm labor onset in their mothers. This was a prospective observational study held in the Neonatal Intensive Care Unit, Department of Woman's and Child's Health, Padova University Hospital (Italy). A urine sample was obtained from each patient within 24 h of birth; Mass Spectrometry-based untargeted metabolomics analysis was then conducted. We searched for any significant disparities in the metabolomic profile of preterm newborns subjected to antenatal corticosteroid (ACS) treatment at varying timings; their correlation with clinical outcomes were also evaluated. The group receiving ACS within the optimal time window (1-7 days before delivery) exhibited elevated levels of cysteine, N-acetylglutamine, propionyl carnitine and 5-hydroxyindolacetic acid, coupled with a decrease in pipecolic acid. Clinically, this group demonstrated a reduced need for invasive ventilation (p = 0.04). In conclusion, metabolomics analysis identified several metabolites that discriminated preterm infants whose mothers received ACS within the recommended time window. Elevated levels of cysteine and 5-Hydroxyindoleacetic acid, metabolites characterized by antioxidant and anti-inflammatory properties, were observed in these infants. This metabolic profile correlated with improved respiratory outcomes, as evidenced by a reduced necessity for invasive ventilation at birth.

Randomized trial of screening for preterm birth in low-risk women - the preterm birth screening study.

BACKGROUND: Preterm birth is a major cause of perinatal morbidity and mortality. It is unclear whether the introduction of a universal transvaginal ultrasound cervical length screening program in women at low risk for preterm delivery is associated with a reduction in the frequency of preterm birth. OBJECTIVE: To test the hypothesis that the introduction of a midtrimester universal transvaginal ultrasound cervical length screening program in asymptomatic singleton pregnancies without prior preterm delivery would reduce the rate of preterm birth at <37 weeks of gestation. STUDY DESIGN: This study was a multicenter nonblinded randomized trial of screening of asymptomatic singleton pregnancies without prior spontaneous preterm birth, who were randomized to either cervical length screening program (ie, intervention group) or no screening (ie, control group). Participants were randomized at the time of their routine anatomy scan between 18 0/7 and 23 6/7 weeks of gestation. Women randomized in the screening group received cervical length measurement. Those who were found to have cervical length ≤25 mm were offered 200 mg vaginal progesterone daily along with cervical pessary. The primary outcome was preterm birth at <37 weeks. The risk of primary outcome was quantified by the relative risk with 95% confidence interval, and was based on the intention-to-screen principle. RESULTS: A total of 1334 asymptomatic women with singleton pregnancies and without prior preterm birth, were included in the trial. Out of the 675 women randomized in the transvaginal ultrasound cervical length screening group, 13 (1.9%) were found to have transvaginal ultrasound cervical length ≤25 mm during the screening. Preterm birth at <37 weeks of gestation occurred in 48 women in the transvaginal ultrasound cervical length screening group (7.5%), and 54 women in the control group (8.7%) (relative risk, 0.86; 95% confidence interval, 0.59-1.25). Women randomized in the transvaginal ultrasound cervical length screening group had no significant differences in the incidence of preterm birth at less than 34, 32, 30, 28, and 24 weeks of gestation. CONCLUSION: The introduction of a universal transvaginal ultrasound cervical length screening program at 18 0/6 to 23 6/7 weeks of gestation in singleton pregnancies without prior spontaneous preterm birth, with treatment for those with cervical length ≤25 mm, did not result in significant lower incidence of preterm delivery than the incidence without the screening program.

A national survey on current practice of ultrasound in labor ward.

OBJECTIVES: Use of ultrasonography has been suggested as an accurate adjunct to clinical evaluation of fetal position and station during labor. There are no available reports concerning its actual use in delivery wards. The aim of this survey was to evaluate the current practice regarding the use of ultrasonography during labor. METHODS: A questionnaire was sent to members of the Italian Society of Ultrasound in Obstetrics and Gynecology employed in delivery wards. The qFeuestionnaire was made up of 22 questions evaluating participant characteristics and the current use of ultrasound in labor in their hospital of employment. The answers were grouped according to participant characteristics. RESULTS: A total of 200 participants replied. Ultrasound was considered useful before an operative vaginal delivery by 59.6 % of respondents, while 51.8 and 52.5 % considered it useful in the management of prolonged first and second stages of labor, respectively. The major indication for ultrasound use during labor was the assessment of fetal occiput position. The major difficulties in its application were the perceived lack of training and the complexity of the ultrasound equipment use. Participants that reported fewer difficulties were those employed in hospitals with a higher number of deliveries or having delivery units with more years of experience using ultrasound in labor, or those who had attended specific training courses. CONCLUSIONS: The results indicate that, despite the reported evidence of a higher accuracy of ultrasound compared to clinical evaluation in assessing fetal position and station, its use is still limited, even amongst maternal-fetal medicine practitioners specialized in ultrasonography.

Mass spectrometry-based "omics" technologies for the study of gestational diabetes and the discovery of new biomarkers.

Gestational diabetes (GDM) is one of the most common complications occurring during pregnancy. Diagnosis is performed by oral glucose tolerance test, but harmonized testing methods and thresholds are still lacking worldwide. Short-term and long-term effects include obesity, type 2 diabetes, and increased risk of cardiovascular disease. The identification and validation of sensitidve, selective, and robust biomarkers for early diagnosis during the first trimester of pregnancy are required, as well as for the prediction of possible adverse outcomes after birth. Mass spectrometry (MS)-based omics technologies are nowadays the method of choice to characterize various pathologies at a molecular level. Proteomics and metabolomics of GDM were widely investigated in the last 10 years, and various proteins and metabolites were proposed as possible biomarkers. Metallomics of GDM was also reported, but studies are limited in number. The present review focuses on the description of the different analytical methods and MS-based instrumental platforms applied to GDM-related omics studies. Preparation procedures for various biological specimens are described and results are briefly summarized. Generally, only preliminary findings are reported by current studies and further efforts are required to determine definitive GDM biomarkers.

Prenatal environment and developmental trajectories: the intrauterine growth restriction.

The prenatal environment is of fundamental importance for the fetus, as the fetus is particularly susceptible to environmental influences while in utero, and several prenatal adversities may constitute a risk factor for fetal growth and child development. Intrauterine growth restriction (IUGR) refers to a pregnancy complication involving the inadequate growth of the fetus in utero, with potential programming consequences on the children's brain-behavior development. In this narrative review we will discuss the most recent literature about IUGR children, including their development and their relationship with the prenatal and postnatal environment. In particular, as an attempt to an adaptive response to intrauterine changes, the brain development of IUGR fetuses follows abnormal developmental pathways, which likely has cascade effects on the future neurodevelopmental outcomes of the children. Cognitive and motor functions are in fact impaired, as well as IUGR children present, across studies, poor socio-emotional abilities and a greater risk for internalizing and externalizing behavior problems. The current work also highlights how the postnatal environment, and in particular parental care, has an important role in IUGR development, acting as a protective factor, or otherwise increasing their constitutional vulnerabilities. Overall, this narrative review has important implications for clinical practice, suggesting the need for long-term follow-up care with IUGR children and strategies supporting parent-child interactions as well.

Metabolomic profiling of intrauterine growth-restricted preterm infants: a matched case-control study.

BACKGROUND: The biochemical variations occurring in intrauterine growth restriction (IUGR), when a fetus is unable to achieve its genetically determined potential, are not fully understood. The aim of this study is to compare the urinary metabolomic profile between IUGR and non-IUGR very preterm infants to investigate the biochemical adaptations of neonates affected by early-onset-restricted intrauterine growth. METHODS: Neonates born <32 weeks of gestation admitted to neonatal intensive care unit (NICU) were enrolled in this prospective matched case-control study. IUGR was diagnosed by an obstetric ultra-sonographer and all relevant clinical data during NICU stay were captured. For each subject, a urine sample was collected within 48 h of life and underwent untargeted metabolomic analysis using mass spectrometry ultra-performance liquid chromatography. Data were analyzed using multivariate and univariate statistical analyses. RESULTS: Among 83 enrolled infants, 15 IUGR neonates were matched with 19 non-IUGR controls. Untargeted metabolomic revealed evident clustering of IUGR neonates versus controls showing derangements of pathways related to tryptophan and histidine metabolism and aminoacyl-tRNA and steroid hormones biosynthesis. CONCLUSIONS: Neonates with IUGR showed a distinctive urinary metabolic profile at birth. Although results are preliminary, metabolomics is proving to be a promising tool to explore biochemical pathways involved in this disease. IMPACT: Very preterm infants with intrauterine growth restriction (IUGR) have a distinctive urinary metabolic profile at birth. Metabolism of glucocorticoids, sexual hormones biosynthesis, tryptophan-kynurenine, and methionine-cysteine pathways seem to operate differently in this sub-group of neonates. This is the first metabolomic study investigating adaptations exclusively in extremely and very preterm infants affected by early-onset IUGR. New knowledge on metabolic derangements in IUGR may pave the ways to further, more tailored research from a perspective of personalized medicine.

Commentary on Special Issue "Fetal Growth: What Is New in the Clinical Research?"

Fetal growth restriction (FGR) is a common complication of pregnancy (3-10%) and has been associated with a variety of adverse perinatal outcomes [...].

Hyperactivation of Wnt/ß-catenin and Jak/Stat3 pathways in human and zebrafish foetal growth restriction models: Implications for pharmacological rescue.

Foetal Growth Restriction (FGR), previously known as Intrauterine Growth Restriction (IUGR), is an obstetrical condition due to placental insufficiency, affecting yearly about 30 million newborns worldwide. In this work, we aimed to identify and pharmacologically target signalling pathways specifically involved in the FGR condition, focusing on FGR-related cardiovascular phenotypes. The transcriptional profile of human umbilical cords from FGR and control cases was compared with the response to hypoxia of zebrafish (Danio rerio) transgenic lines reporting in vivo the activity of twelve signalling pathways involved in embryonic development. Wnt/ß-catenin and Jak/Stat3 were found as key pathways significantly dysregulated in both human and zebrafish samples. This information was used in a chemical-genetic analysis to test drugs targeting Wnt/ß-catenin and Jak/Stat3 pathways to rescue a set of FGR phenotypes, including growth restriction and cardiovascular modifications. Treatments with the Wnt/ß-catenin agonist SB216763 successfully rescued body dimensions, cardiac shape, and vessel organization in zebrafish FGR models. Our data support the Wnt/ß-catenin pathway as a key FGR marker and a promising target for pharmacological intervention in the FGR condition.

Fetal Doppler Evaluation to Predict NEC Development.

Antenatal factors play a role in NEC pathogenesis. This study aimed to investigate the predictive value of fetal ductus venosus doppler (DV) for NEC in fetal growth restriction fetuses (FGRF) and to assess the predictive accuracy of IG21 and Fenton curves in NEC development. Data from FGRF, postnatal findings, and Doppler characteristics were collected between 2010 and 2020 at a single center. Patients were then divided into two groups (i.e., with and without NEC). Bivariate and multivariate analyses were performed. We identified 24 cases and 30 controls. Absent or reversed end-diastolic flow (AREDF) and increased resistance in the DV were more impaired in cases (p < 0.05). Although the median birthweight was not different, the Fenton z-score was lower in NEC (p < 0.05). Fetal cardiopulmonary resuscitation, synchronized intermittent mandatory ventilation, neonatal respiratory distress, persistent patent ductus arteriosus (PDA), and inotropic support were more frequent in the NEC group. Furthermore, NEC patients had lower white blood cells (WBC) (p < 0.05). The predictive model for NEC (model 4), including Fenton z-score, WBC, PDA, and DV had an AUC of 84%. Fetal Doppler findings proved effective in predicting NEC in FGR. The Fenton z-score was the most predictive factor considering the fetal growth assessment showing high sensitivity.

DHA turnover in pregnant women using the natural abundance variation of 13C: a pilot study.

The importance of DHA intake to support fetal development and maternal health is well established. In this pilot study we applied the natural abundance approach to determine the contribution of 200 mg/day of DHA supplement to the plasma DHA pool in 19 healthy pregnant women on a free diet.Women received DHA, from pregnancy week 20 until delivery, from an algal source (N=13, Algae group) or from fish oil (N=6, Fish group) with slightly different content of 13C.We measured plasma phospholipids DHA 13C:12C ratio (reported as δ13C) prior to supplementation (T0), after 10 (T1) and 90 days (T2) and prior to delivery (T3).The δ13C of DHA in algae and fish supplements were -15.8±0.2 mUr and -25.3±0.2 mUr (p<0.001).DHA δ13C in the Algae group increased from -27.7±1.6 mUr (T0) to -21.9±2.2 mUr (T3) (p<0.001), whereas there were not significant changes in the Fish group (-27.8±0.9 mUr at T0 and -27.3±1.1 mUr at T3, p=0.09).In the Algae group 200 mg/day of DHA contributed to the plasma phospholipid pool by a median value of 53% (31-75% minimum and maximum). This estimation was not possible in the fish group.Our results demonstrate the feasibility of assessing the contribution of DHA from an algal source to the plasma DHA pool in pregnant women by the natural abundance approach. Plasma δ13C DHA did not change when consuming DHA of fish origin, with almost the same δ13C value of that of the pre-supplementation plasma δ13C DHA.

A prenatal standard for fetal weight improves the prenatal diagnosis of small for gestational age fetuses in pregnancies at increased risk.

OBJECTIVE: Our aim was to assess diagnostic accuracy in the prediction of small for gestational age (SGA <10th centile) and fetal growth restricted (FGR) (SGA <3rd centile) fetuses using three different sonographic methods in pregnancies at increased risk of fetal growth restriction: 1) fetal abdominal circumference (AC) z-scores, 2) estimated fetal weight (EFW) z-scores according to postnatal reference standard; 3) EFW z-scores according to a prenatal reference standard. METHODS: Singleton pregnancies at increased risk of fetal growth restriction seen in two university hospitals between 2014 and 2015 were studied retrospectively. EFW was calculated using formulas proposed by the INTERGROWTH-21st project and Hadlock; data derived from publications by the INTEGROWTH-twenty-first century project and Hadlock were used to calculate z-scores (AC and EFW). The accuracy of different methods was calculated and compared. RESULTS: The study group included 406 patients. Prenatal standard EFW z-scores derived from INTERGROWTH-21st project and Hadlock and co-workers performed similarly and were more accurate in identifying SGA infants than using AC z-scores or a postnatal reference standard. The subgroups analysis demonstrated that EFW prenatal standard was more or similarly accurate compared to other methods across all subgroups, defined by gestational age and birth weight. CONCLUSIONS: Prenatal standard EFW z-scores derived from either INTERGROWTH-21 st project or Hadlock and co-workers publications demonstrated a statistically significant advantage over other biometric methods in the diagnosis of SGA fetuses.

Diet in pregnant women that delivered prematurely and preterm newborn's bone status.

OBJECTIVES: Inadequate maternal dietary pattern has been associated to negative pregnancy and fetal outcomes. With this study, we aimed to evaluate the adequacy of diet in pregnant women that delivered prematurely and its possible correlations with bone status of preterm newborns. STUDY DESIGN: We prospectively enrolled women who delivered prematurely (≤than 34 gestational weeks) and their newborns (Neonatal Intensive Care, University Hospital of Padova) from January 2017 to May 2018. Maternal nutritional status and diet supplementations were assessed using a validated questionnaire. The preterm newborns were evaluated with anthropometric measurements and bone status by Quantitative Ultrasound of the second metacarpal bone within 72 h from birth. RESULTS: One hundred and eighty mothers and 202 preterm newborns were evaluated. The mothers assumed more calories, proteins, total lipids and simple sugars compared to the revised National Guidelines. The intake of calcium, phosphorus and Vitamin D was inadequate despite the use of multivitamin supplements. The mothers assumption of vitamin D and zinc positively correlated with bone status and mothers with very low intake of vitamin D during gestation (<7 µg/die) had preterm newborns with a worst bone status at birth compared to those with a better intake (>7 µg/die). CONCLUSIONS: Nutrition of pregnant women could be improved and maternal intakes of Vitamin D and zinc positively correlated with preterm newborn's bone status.

Four-Year Follow-Up of the Maternal Immunological, Virological and Clinical Settings of a 36-Year-Old Woman Experiencing Primary Cytomegalovirus Infection Leading to Intrauterine Infection.

The present study aims to provide the sequential immunological, clinical and virological events occurring in a CMV-infected pregnant woman experiencing intrauterine CMV transmission. In brief, a case of primary CMV infection occurred in a 36-year-old pregnant woman. The patient exhibited early-sustained viremia and viruria, detectable presence of CMV in saliva concomitant with a strong CMV-specific cell-mediated response (427 EliSpots). CMV was detected in the amniotic fluid at 15 weeks of pregnancy (>1 × 106 CMV copies/mL). The pregnancy was deliberately interrupted at 16 weeks of gestation. Fetal histological and pathological examinations revealed placentitis and fetal brain alterations as microcephaly and cortical dysplasia. Interestingly, this clinical report shows: (1) there was a rapid and sustained CMV-specific cell mediated immune response (Th1) in association with low IgG avidity (Th2) correlated with fetal CMV transmission. (2) The levels of CMV-specific cell-mediated immune response persisted at high levels up to 200 weeks after infection despite clinical and viral clearance. (3) The histological and pathological evidence suggests that a potent pro-inflammatory condition at the placental level may lead to cCMV.

Role of prenatal magnetic resonance imaging in fetuses with isolated severe ventriculomegaly at neurosonography: A multicenter study.

OBJECTIVE: The aim of this study was to report the rate of additional anomalies detected exclusively at prenatal magnetic resonance imaging (MRI) in fetuses with isolated severe ventriculomegaly undergoing neurosonography. METHOD: Multicenter, retrospective, cohort study involving 20 referral fetal medicine centers in Italy, United Kingdom, Spain and Denmark. Inclusion criteria were fetuses affected by isolated severe ventriculomegaly (≥15 mm), defined as ventriculomegaly with normal karyotype and no other additional central nervous system (CNS) and extra-CNS anomalies on ultrasound. In all cases, a multiplanar assessment of fetal brain as suggested by ISUOG guidelines on fetal neurosonography had been performed. The primary outcome was the rate of additional CNS anomalies detected exclusively at fetal MRI within two weeks from neurosonography. Subgroup analyses according to gestational age at MRI (

Isolated Dissection of the Ductus Arteriosus Associated with Sudden Unexpected Intrauterine Death.

We report five cases of sudden intrauterine death due to premature closure of the ductus arteriosus. In four cases, this was caused by dissecting the hematoma of the ductus arteriosus with intimal flap and obliteration of the lumen. In one case, the ductus arteriosus was aneurysmatic, with lumen occlusion caused by thrombus stratification. No drug therapy or free medication consumption were reported during pregnancy. The time of stillbirth ranged between 26 and 33 gestational weeks. We performed TUNEL analysis for apoptosis quantification. The dissecting features were intimal tears with flap formation in four of the cases, just above the origin of the ductus arteriosus from the pulmonary artery. The dissecting hematoma of the ductus arteriosus extended downward to the descending aorta and backward to the aortic arch with involvement of the left carotid and left subclavian arteries. TUNEL analysis showed a high number of apoptotic smooth muscle cells in the media in two cases. Abnormal ductal remodeling with absence of subintimal cushions, lacunar spaces rich in glycosaminoglycans (cystic medial necrosis), and smooth muscle cell apoptosis were the pathological substrates accounting for failure of remodeling process and dissection.

Maternal-fetal attachment in pregnant Italian women: multidimensional influences and the association with maternal caregiving in the infant's first year of life.

BACKGROUND: Maternal-Fetal Attachment (MFA) describes the cognitive-representational, emotional, and behavioral aspects of the mother-fetus relationship that develops during pregnancy. We present two studies conducted on pregnant Italian women. In Study I, we aimed to explore multifaceted associations of MFA with variables important for a healthy pregnancy (e.g., maternal mental health, the couple's relationship). In Study II, we investigated the predictive role of MFA on observed maternal caregiving during the first months of the infant's life. METHODS: In Study I, 113 pregnant Italian women were assessed on MFA (Maternal Antenatal Attachment Scale, MAAS), maternal depression (Beck Depression Inventory-II, BDI-II), maternal anxiety (State Trait Anxiety Inventory - State version, STAI), adjustment of the couple (Dyadic Adjustment Scale, DAS), and perceived parental care (The Parental Bonding Instrument, PBI). In Study II, 29 mother-infant pairs were followed up at 4 months to assess observational variables of maternal caregiving through the Emotional Availability Scale (EAS) and to test for an association with MFA in pregnancy. RESULTS: Study I showed a significant association between MFA and the quality of the couple relationship (ß = .49, P < .001) and between MFA and the recall of memories of care received in childhood (ß = .22, P = .025). Study II showed a predictive effect of MFA on maternal structuring observed during mother-infant interactions at 4 months of age (ß = 0.36, P = .046). CONCLUSION: The study points out relevant relationship contexts that might receive care and support throughout pregnancy to protect MFA. The findings also provide thoughtful insights on the role of MFA in early maternal caregiving, suggesting that MFA might be a candidate as one putative antecedent of mother-infant interaction processes.

Neonatal lymphocyte subpopulations analysis and maternal preterm premature rupture of membranes: a pilot study.

OBJECTIVES: Preterm premature rupture of membranes (pPROM) causes preterm delivery, and increases maternal T-cell response against the fetus. Fetal inflammatory response prompts maturation of the newborn's immunocompetent cells, and could be associated with unfavorable neonatal outcome. The aims were (1) to examine the effects of pPROM on the newborn's and mother's immune system and (2) to assess the predictive value of immune system changes in neonatal morbidity. METHODS: Mother-newborn pairs (18 mothers and 23 newborns) who experienced pPROM and controls (11 mothers and 14 newborns), were enrolled. Maternal and neonatal whole blood samples underwent flow cytometry to measure lymphocyte subpopulations. RESULTS: pPROM-newborns had fewer naïve CD4 T-cells, and more memory CD4 T-cells than control newborns. The effect was the same for increasing pPROM latency times before delivery. Gestational age and birth weight influenced maturation of the newborns' lymphocyte subpopulations and white blood cells, notably cytotoxic T-cells, regulatory T-cells, T-helper cells (absolute count), and CD4/CD8 ratio. Among morbidities, fewer naïve CD8 T-cells were found in bronchopulmonary dysplasia (BPD) (p=0.0009), and more T-helper cells in early onset sepsis (p=0.04). CONCLUSIONS: pPROM prompts maturation of the newborn's T-cell immune system secondary to antigenic stimulation, which correlates with pPROM latency. Maternal immunity to inflammatory conditions is associated with a decrease in non-major histocompatibility complex (MHC)-restricted cytotoxic cells.

Use of the Renal Artery Doppler to Identify Small for Gestational Age Fetuses at Risk for Adverse Neonatal Outcomes.

OBJECTIVE: To measure the sensitivity and positive predictive value (PPV) for an adverse neonatal outcome among growth-restricted fetuses (FGR) comparing the cerebral-placental ratio (CPR) with the cerebral-renal ratio (CRR). METHODS: Retrospective analysis of 92 women who underwent prenatal ultrasound at the University of Maryland and the University of Padua. Renal, middle cerebral and umbilical artery Doppler waveforms were recorded for all scans during the third trimester. The last scan prior to delivery was included for analysis. We calculated the test characteristics of the pulsatility indices (PI) of the umbilical and renal arteries in addition to the derived CPR and CRR to detect a composite adverse neonatal outcome. RESULTS: The test characteristics of the four Doppler ratios to detect increased risk for the composite neonatal outcome demonstrated that the umbilical artery pulsatility index had the best test performance (sensitivity 64% (95% CI: 47-82%), PPV 24% (95% CI: 21-27), and positive likelihood ratio 2.7 (95% CI: 1.4-5.2)). There was no benefit to using the CRR compared with the CPR. The agreement between tests was moderate to poor (Kappa value CPR compared with CRR: 0.5 (95%CI 0.4-0.70), renal artery PI:-0.1 (95% CI -0.2-0.0), umbilical artery PI: 0.5 (95% CI 0.4-0.7)). Only the umbilical artery had an area under the receiver operating curve that was significantly better compared with the CPR as a reference (p-value < 0.01). CONCLUSIONS: The data that we present do not support the use of renal artery Doppler as a useful clinical test to identify a fetus at risk for an adverse neonatal outcome. Within the various indices applied to this population, umbilical artery Doppler performed the best in identifying the fetuses at risk for an adverse perinatal outcome.

Adverse intrapartum outcome in pregnancies complicated by small for gestational age and late fetal growth restriction undergoing induction of labor with Dinoprostone, Misoprostol or mechanical methods: A systematic review and meta-analysis.

OBJECTIVE: To investigate the outcome of pregnancies with small baby, including both small for gestational age (SGA) and late fetal growth restriction (FGR) fetuses, undergoing induction of labor (IOL) with Dinoprostone, Misoprostol or mechanical methods. STUDY DESIGN: Medline, Embase and Cochrane databases were searched. Inclusion criteria were non-anomalous singleton pregnancies complicated by the presence of a small fetus, defined as a fetus with estimated fetal weight (EFW) or abdominal circumference (AC) <10th centile undergoing IOL from 34 weeks of gestation with vaginal Dinoprostone, vaginal misoprostol, or mechanical methods (including either Foley or Cook balloon catheters). The primary outcome was a composite measure of adverse intrapartum outcome. Secondary outcomes were the individual components of the primary outcome, perinatal mortality and morbidity. All the explored outcomes were reported in three different sub-groups of pregnancies complicated by a small fetus including: all small fetuses (defined as those with an EFW and/or AC <10th centile irrespective of fetal Doppler status), late FGR fetuses (defined as those with EFW and/or AC <3rd centile or AC/EFW <10th centile associated with abnormal cerebroplacental Dopplers) and SGA fetuses (defined as those with EFW and/or AC <10th but >3rd centile with normal cerebroplacental Dopplers). Quality assessment of each included study was performed using the Risk of Bias in Non-randomized Studies-of Interventions tool (ROBINS-I), while the GRADE methodology was used to assess the quality of the body of retrieved evidence. Meta-analyses of proportions and individual data random-effect logistic regression were used to analyze the data. RESULTS: 12 studies (1711 pregnancies) were included. In the overall population of small fetuses, composite adverse intra-partum outcome occurred in 21.2 % (95 % CI 10.0-34.9) of pregnancies induced with Dinoprostone, 18.0 % (95 % CI 6.9-32.5) of those with Misoprostol and 11.6 % (95 % CI 5.5-19.3) of those undergoing IOL with mechanical methods. Cesarean section (CS) for non-reassuring fetal status (NRFS) was required in 18.1 % (95 % CI 9.9-28.3) of pregnancies induced with Dinoprostone, 9.4 % (95 % CI 1.4-22.0) of those with Misoprostol and 8.1 % (95 % CI 5.0-11.6) of those undergoing mechanical induction. Likewise, uterine tachysystole, was recorded on CTG in 13.8 % (95 % CI 6.9-22.3) of cases induced with Dinoprostone, 7.5 % (95 % CI 2.1-15.4) of those with Misoprostol and 3.8 % (95 % CI 0-4.4) of those induced with mechanical methods. Composite adverse perinatal outcome following delivery complicated 2.9 % (95 % CI 0.5-6.7) newborns after IOL with Dinoprostone, 0.6 % (95 % CI 0-2.5) with Misoprostol and 0.7 % (95 % CI 0-7.1) with mechanical methods. In pregnancies complicated by late FGR, adverse intrapartum outcome occurred in 25.3 % (95 % CI 18.8-32.5) of women undergoing IOL with Dinoprostone, compared to 7.4 % (95 % CI 3.9-11.7) of those with mechanical methods, while CS for NRFS was performed in 23.8 % (95 % CI 17.3-30.9) and 6.2 % (95 % CI 2.8-10.5) of the cases, respectively. Finally, in SGA fetuses, composite adverse intrapartum outcome complicated 8.4 % (95 % CI 4.6-13.0) of pregnancies induced with Dinoprostone, 18.6 % (95 % CI 13.1-25.2) of those with Misoprostol and 8.7 (95 % CI 2.5-17.5) of those undergoing mechanical IOL, while CS for NRF was performed in 8.4 % (95 % CI 4.6-13.0) of women induced with Dinoprostone, 18.6 % (95 % CI 13.1-25.2) of those with Misoprostol and 8.7 % (95 % CI 2.5-17.5) of those undergoing mechanical induction. Overall, the quality of the included studies was low and was downgraded due to considerable clinical and statistical heterogeneity. CONCLUSIONS: There is limited evidence on the optimal type of IOL in pregnancies with small fetuses. Mechanical methods seem to be associated with a lower occurrence of adverse intrapartum outcomes, but a direct comparison between different techniques could not be performed.