Effectiveness of routine third trimester ultrasonography to reduce adverse perinatal outcomes in low risk pregnancy (the IRIS study): nationwide, pragmatic, multicentre, stepped wedge cluster randomised trial

Abstract

ObjectivesTo investigate the effectiveness of routine ultrasonography in the third trimester in reducing adverse perinatal outcomes in low risk pregnancies compared with usual care and the effect of this policy on maternal outcomes and obstetric interventions.DesignPragmatic, multicentre, stepped wedge cluster randomised trial.Setting60 midwifery practices in the Netherlands.Participants13 046 women aged 16 years or older with a low risk singleton pregnancy.Interventions60 midwifery practices offered usual care (serial fundal height measurements with clinically indicated ultrasonography). After 3, 7, and 10 months, a third of the practices were randomised to the intervention strategy. As well as receiving usual care, women in the intervention strategy were offered two routine biometry scans at 28-30 and 34-36 weeks’ gestation. The same multidisciplinary protocol for detecting and managing fetal growth restriction was used in both strategies.Main outcome measuresThe primary outcome measure was a composite of severe adverse perinatal outcomes: perinatal death, Apgar score <4, impaired consciousness, asphyxia, seizures, assisted ventilation, septicaemia, meningitis, bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leucomalacia, or necrotising enterocolitis. Secondary outcomes were two composite measures of severe maternal morbidity, and spontaneous labour and birth.ResultsBetween 1 February 2015 and 29 February 2016, 60 midwifery practices enrolled 13 520 women in mid-pregnancy (mean 22.8 (SD 2.4) weeks’ gestation). 13 046 women (intervention n=7067, usual care n=5979) with data based on the national Dutch perinatal registry or hospital records were included in the analyses. Small for gestational age at birth was significantly more often detected in the intervention group than in the usual care group (179 of 556 (32%) v 78 of 407 (19%), P<0.001). The incidence of severe adverse perinatal outcomes was 1.7% (n=118) for the intervention strategy and 1.8% (n=106) for usual care. After adjustment for confounders, the difference between the groups was not significant (odds ratio 0.88, 95% confidence interval 0.70 to 1.20). The intervention strategy showed a higher incidence of induction of labour (1.16, 1.04 to 1.30) and a lower incidence of augmentation of labour (0.78, 0.71 to 0.85). Maternal outcomes and other obstetric interventions did not differ between the strategies.ConclusionIn low risk pregnancies, routine ultrasonography in the third trimester along with clinically indicated ultrasonography was associated with higher antenatal detection of small for gestational age fetuses but not with a reduced incidence of severe adverse perinatal outcomes compared with usual care alone. The findings do not support routine ultrasonography in the third trimester for low risk pregnancies.Trial registrationNetherlands Trial Register NTR4367.

Induction of labour at 41 weeks or expectant management until 42 weeks: A systematic review and an individual participant data meta-analysis of randomised trials

“…Perinatal mortality did not occur in the expectant management group in Stockholm centres (0/557; 0.0%), whereas in the other centres, there were six cases (6/822; 0.7%). However, there is currently insufficient evidence that routine surveillance with ultrasonographic assessment in late term in order to detect fetuses at risk reduces perinatal mortality [36][37][38][39]. In a Swedish retrospective study, a reduction in SGA but no reduction in rates of composite perinatal mortality and morbidity or stillbirth was found with routine ultrasound at 41 weeks compared with indicated ultrasound [38].…”

Stillbirth at term: Does size really matter?

“…Increased risk of placental dysfunction identified by any of these means usually triggers ultrasound evaluation for fetal growth and well‐being 8 . This is still the strategy currently practiced in the majority of obstetric units, 9 although a universal approach of third‐trimester ultrasound screening has been shown to double the detection of SGA fetuses and triple the detection of severe SGA with estimated fetal weight (EFW) below the third centile for gestational age 10,11 . Assessment of ultrasound under these circumstances follows two main steps: measurement of fetal biometry to calculate EFW and plotting the EFW on a chart to establish a fetal weight centile for the given gestational age.…”

The bivariate NRIP1/ZEB2 RNA marker permits non-invasive presymptomatic screening of pre-eclampsia

“…Of the pregnancies with fetal birth weights below the 10th percentile (n = 11), three (27.3%) had distinct presymptomatic profiles. This percentage would correlate with the percentage of true cases with intrauterine growth retardation as predicted by the nationwide, multicentre, stepped wedge cluster randomised trial in the Netherlands 12 .…”

“…This can be explained by considering pregnancies with fetal growth restriction. About 70% of fetuses with a birth weight below the 10th percentile are not growth restricted, have similar uncomplicated perinatal outcomes compared to those with fetal weight in the normal range and should be considered normal variations in fetal growth (small-for-gestational age, SGA) 12 . This implies the more realistic situation in all clinical cohorts including our own, 30% of pregnancies with birth weights below the 10th percentile will be truly growth-retarded (IUGR) and have signs of (early) placental dysfunction.…”

“…This implies the more realistic situation in all clinical cohorts including our own, 30% of pregnancies with birth weights below the 10th percentile will be truly growth-retarded (IUGR) and have signs of (early) placental dysfunction. In other words, commonly used late clinical parameters like birth weight lack specificity and constrain informativity when used as paradigm for early pathophysiological events 12 .…”