Prévention du RCIU vasculaire

Maternal Obesity and Risk of Low Birth Weight, Fetal Growth Restriction, and Macrosomia: Multiple Analyses

The associations between maternal pre-pregnancy obesity and low birth weight (LBW, <2500 g) remain inconclusive. Therefore, birth weight in a Polish prospective cohort of 912 mothers was investigated depending on the pre-pregnancy body mass index (BMI). The whole cohort and the subgroup of gestational weight gain (GWG) in the range of the Institute of Medicine (IOM) recommendations, as well as 'healthy' women (who did not develop diabetes or hypertension in this pregnancy) were investigated. Adjusted odds ratios (AOR) of the newborn outcomes (with 95% confidence intervals, CI) for obesity (BMI ≥ 30 kg/m²) vs. normal BMI (18.5-24.9 kg/m²) were calculated using multiple logistic regression. Risk profiles (in the Lowess method) were presented for BMI values (kg/m²) and threshold BMI values were calculated. (1) In the cohort, LBW affected 6.6% of pregnancies, fetal growth restriction (FGR) 2.3%, and macrosomia 10.6%. (2) The adjusted risk of macrosomia was more than three-fold higher for obesity compared to normal BMI in the whole cohort (AOR = 3.21 (1.69-6.1), p < 0.001) and the result was maintained in the subgroups. A 17-fold higher adjusted LBW risk for obesity was found (AOR = 17.42 (1.5-202.6), p = 0.022), but only in the normal GWG subgroup. The FGR risk profile was U-shaped: in the entire cohort, the risk was more than three times higher for obesity (AOR = 3.12 (1.02-9.54), p = 0.045) and underweight (AOR = 3.84 (1.13-13.0), p = 0.031). (3) The risk profiles showed that the highest BMI values were found to be associated with a higher risk of these three newborn outcomes and the threshold BMI was 23.7 kg/m² for macrosomia, 26.2 kg/m² for LBW, and 31.8 kg/m² for FGR. These results confirm the multidirectional effects of obesity on fetal growth (low birth weight, fetal growth restriction, and macrosomia). The results for LBW were heavily masked by the effects of abnormal gestational weight gain.

[For a targeted use of aspirin]

The use of low-dose aspirin in pregnancy should remain a highly targeted indication since its long-term safety has not been established and should be restricted to women at high risk of vascular complications. Indications for which the benefit of aspirin has been shown are women with a history of preeclampsia responsible for a premature birth before 34 weeks, those having at least two history of preeclampsia, those with an antiphospholipid syndrome and those with lupus associated with positive antiphospholipid antibodies or renal failure. In all other cases, the level of evidence of the benefit of aspirin is insufficient to recommend its routine prescription.

The Burden of Provider-Initiated Preterm Birth and Associated Factors: Evidence from the Brazilian Multicenter Study on Preterm Birth (EMIP)

Background

About 15 million children are born under 37 weeks of gestation worldwide. Prematurity is the leading cause of neonatal deaths and short/long term morbidities, entailing consequences not only for the individual, but also their family, health agencies, facilities and all community. The provider-initiated preterm birth is currently one of the most important obstetric conditions related to preterm births, particularly in middle and high income countries, thus decreasing the need for therapeutic preterm birth is essential to reduce global prematurity. Therefore detailed knowledge on the factors associated with provider-initiated preterm birth is essential for the efforts to reduce preterm birth rates and its consequences. In this current analysis we aimed to assess the proportion of provider-initiated (pi-PTB) among preterm births in Brazil and identify associated factors.

Methods and Findings

This is an analysis of a multicenter cross-sectional study with a nested case-control component called Brazilian Multicenter Study on Preterm Birth (EMIP). EMIP was conducted in 20 referral obstetric hospitals located in the three most populated of the five Brazilian regions. We analysed data of women with pi-PTB, defined as childbirth occurring at less than 37 weeks, medically indicated for maternal/fetal compromise or both; and women with term birth, childbirth at or after 37 weeks. Maternal, sociodemographic, obstetric, prenatal care, delivery, and postnatal characteristics were assessed as possible factors associated with pi-PTB, compared to term births. The overall prevalence of preterm births was 12.3%. Of these, approximately one-third of cases were initiated by the provider. Hypertensive disorders, placental abruption, and diabetes were the main maternal conditions leading to pi-PTB. Caesarean section was the most common mode of delivery. Chronic hypertension (OR 7.47; 95%CI 4.02–13.88), preeclampsia/eclampsia/HELLP syndrome (OR 15.35; 6.57–35.88), multiple pregnancy (OR 12.49; 4.86–32.05), and chronic diabetes (OR 5.24; 2.68–10.25) were the most significant factors independently associated with pi-PTB.

Conclusions

pi-PTB is responsible for about one-third of all preterm births, requiring special attention. The decision-making process relative to the choice of provider-initiated birth is complex, and many factors should be elucidated to improve strategies for its prevention, including evidence-based guidelines on proper management of the corresponding clinical conditions.

Fetal growth restriction and intra-uterine growth restriction: guidelines for clinical practice from the French College of Gynaecologists and Obstetricians

Small for gestational age (SGA) is defined by weight (in utero estimated fetal weight or birth weight) below the 10th percentile (professional consensus). Severe SGA is SGA below the third percentile (professional consensus). Fetal growth restriction (FGR) or intra-uterine growth restriction (IUGR) usually correspond with SGA associated with evidence indicating abnormal growth (with or without abnormal uterine and/or umbilical Doppler): arrest of growth or a shift in its rate measured longitudinally (at least two measurements, 3 weeks apart) (professional consensus). More rarely, they may correspond with inadequate growth, with weight near the 10th percentile without being SGA (LE2). Birthweight curves are not appropriate for the identification of SGA at early gestational ages because of the disorders associated with preterm delivery. In utero curves represent physiological growth more reliably (LE2). In diagnostic (or reference) ultrasound, the use of growth curves adjusted for maternal height and weight, parity and fetal sex is recommended (professional consensus). In screening, the use of adjusted curves must be assessed in pilot regions to determine the schedule for their subsequent introduction at national level. This choice is based on evidence of feasibility and the absence of any proven benefits for individualized curves for perinatal health in the general population (professional consensus). Children born with FGR or SGA have a higher risk of minor cognitive deficits, school problems and metabolic syndrome in adulthood. The role of preterm delivery in these complications is linked. The measurement of fundal height remains relevant to screening after 22 weeks of gestation (Grade C). The biometric ultrasound indicators recommended are: head circumference (HC), abdominal circumference (AC) and femur length (FL) (professional consensus). They allow calculation of estimated fetal weight (EFW), which, with AC, is the most relevant indicator for screening. Hadlock's EFW formula with three indicators (HC, AC and FL) should ideally be used (Grade B). The ultrasound report must specify the percentile of the EFW (Grade C). Verification of the date of conception is essential. It is based on the crown-rump length between 11 and 14 weeks of gestation (Grade A). The HC, AC and FL measurements must be related to the appropriate reference curves (professional consensus); those modelled from College Francais d'Echographie Fetale data are recommended because they are multicentere French curves (professional consensus). Whether or not a work-up should be performed and its content depend on the context (gestational age, severity of biometric abnormalities, other ultrasound data, parents' wishes, etc.) (professional consensus). Such a work-up only makes sense if it might modify pregnancy management and, in particular, if it has the potential to reduce perinatal and long-term morbidity and mortality (professional consensus). The use of umbilical artery Doppler velocimetry is associated with better newborn health status in populations at risk, especially in those with FGR (Grade A). This Doppler examination must be the first-line tool for surveillance of fetuses with SGA and FGR (professional consensus). A course of corticosteroids is recommended for women with an FGR fetus, and for whom delivery before 34 weeks of gestation is envisaged (Grade C). Magnesium sulphate should be prescribed for preterm deliveries before 32-33 weeks of gestation (Grade A). The same management should apply for preterm FGR deliveries (Grade C). In cases of FGR, fetal growth must be monitored at intervals of no less than 2 weeks, and ideally 3 weeks (professional consensus). Referral to a Level IIb or III maternity ward must be proposed in cases of EFW <1500g, potential birth before 32-34 weeks of gestation (absent or reversed umbilical end-diastolic flow, abnormal venous Doppler) or a fetal disease associated with any of these (professional consensus). Systematic caesarean deliveries for FGR are not recommended (Grade C). In cases of vaginal delivery, fetal heart rate must be monitored continuously during labour, and any delay before intervention must be faster than in low-risk situations (professional consensus). Regional anaesthesia is preferred in trials of vaginal delivery, as in planned caesareans. Morbidity and mortality are higher in SGA newborns than in normal-weight newborns of the same gestational age (LE3). The risk of neonatal mortality is two to four times higher in SGA newborns than in non-SGA preterm and full-term infants (LE2). Initial management of an SGA newborn includes combatting hypothermia by maintaining the heat chain (survival blanket), ventilation with a pressure-controlled insufflator, if necessary, and close monitoring of capillary blood glucose (professional consensus). Testing for antiphospholipids (anticardiolipin, circulating anticoagulant, anti-beta2-GP1) is recommended in women with previous severe FGR (below third percentile) that led to birth before 34 weeks of gestation (professional consensus). It is recommended that aspirin should be prescribed to women with a history of pre-eclampsia before 34 weeks of gestation, and/or FGR below the fifth percentile with a probable vascular origin (professional consensus). Aspirin must be taken in the evening or at least 8h after awakening (Grade B), before 16 weeks of gestation, at a dose of 100-160mg/day (Grade A).