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Background Antenatal detection and management of small for gestational age (SGA) is a strategy to reduce stillbirth. Large observational studies provide conflicting results on the effect of the Growth Assessment Protocol (GAP) in relation to detection of SGA and reduction of stillbirth; to the best of our knowledge, there are no reported randomised control trials. Our aim was to determine if GAP improves antenatal detection of SGA compared to standard care. Methods and findings This was a pragmatic, superiority, 2-arm, parallel group, open, cluster randomised control trial. Maternity units in England were eligible to participate in the study, except if they had already implemented GAP. All women who gave birth in participating clusters (maternity units) during the year prior to randomisation and during the trial (November 2016 to February 2019) were included. Multiple pregnancies, fetal abnormalities or births before 24+1 weeks were excluded. Clusters were randomised to immediate implementation of GAP, an antenatal care package aimed at improving detection of SGA as a means to reduce the rate of stillbirth, or to standard care. Randomisation by random permutation was stratified by time of study inclusion and cluster size. Data were obtained from hospital electronic records for 12 months prerandomisation, the washout period (interval between randomisation and data collection of outcomes), and the outcome period (last 6 months of the study). The primary outcome was ultrasound detection of SGA (estimated fetal weight Conclusions In this study, we observed no effect of GAP on antenatal detection of SGA compared to standard care. Given variable implementation observed, future studies should incorporate standardised implementation outcomes such as those reported here to determine generalisability of our findings. Trial registration This trial is registered with the ISRCTN registry, ISRCTN67698474. Matias C Vieira and colleagues evaluate the Growth Assessment Protocol (GAP) for antenatal detection of small for gestational age in the DESiGN cluster randomised trial. Summary Why was this study done? Antenatal detection and appropriate management of small for gestational age (SGA) infants is a recognised strategy to prevent stillbirth; previous reports have suggested the rate of stillbirth is halved when SGA is antenatally detected, compared to undetected SGA. Large observational studies provide conflicting results on the effect of Growth Assessment Protocol (GAP), an antenatal care package, with both findings of increased and no difference in detection of SGA and reduction of stillbirth. The observational nature of all previous studies about GAP limits the assessment of causality in any observed associations. What did the researchers do and find? To the best of our knowledge, this is the first randomised control trial of GAP, comparing 11,096 births exposed to the intervention (5 clusters) to 13,810 exposed to standard care (6 clusters) during the outcome period. We observed no significant effect on antenatal detection of SGA compared to standard care (25.9% versus 27.7%; adjusted difference 2.2%, 95% confidence interval (CI) −6.4% to 10.7%). The lack of effect should be interpreted in the context of the variable implementation of GAP. What do these findings mean? This randomised control trial of GAP compared to standard care did not observe improvement in ultrasound detection of SGA; variable implementation of GAP was observed consistent with previous studies. It is imperative that future studies of GAP assess implementation using standardised outcomes (fidelity, reach, and dose), in order to determine generalisability of our findings, identify barriers to implementation, and hence better inform policy for improving perinatal outcomes. Use of routinely collected data is both a strength (cost-efficient) and a limitation (occurrence of missing data); the modest number of hospitals in this study limits our ability to study small differences between groups.

BackgroundAlthough many studies have compared birth-weight charts to determine which better identify infants at risk of adverse perinatal outcomes, less attention has been given to the threshold used to define small or large for gestational age (SGA or LGA) infants. Our aim was to explore different thresholds associated with increased risk of adverse perinatal outcomes using population, customised, and Intergrowth centile charts.Methods and findingsThis is a population-based cohort study (Swedish Medical Birth Registry), which included term singleton births between 2006 and 2015 from women with available data on first-trimester screening. Population, customised, and Intergrowth charts were studied. Outcomes included cesarean section, postpartum haemorrhage, severe perineal tear, Apgar score at 5 minutes, neonatal morbidity, and perinatal mortality. Odds for each outcome were assessed in intervals of 5 centiles of birth weight (reference being 40th-60th centiles) using logistic regression. Intervals of 5% of the population were also explored. Sensitivity for fixed false-positive rates (FPRs) was reported for neonatal outcomes. Data from 212,101 births were analysed. Mean age was 33 ± 5 years, 48% of women were nulliparous, and 80% were born in Sweden. Prevalence of SGA (90th centile) was 10.0%, 8.2%, and 25.1%, assessed using population, customised, and Intergrowth charts, respectively. In small infants, the risk of perinatal mortality was consistently increased below the 15th, 10th, and 35th birth-weight centiles for the respective charts (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.05-2.39, p = 0.03 for 10th-15th population centile; OR 2.54, 95% CI 1.74-3.71, p < 0.001 for 5th-10th customised centile; OR 1.81, 95% CI 1.07-3.04, p = 0.03 for 30th-35th Intergrowth centile). The strength of association with adverse perinatal outcomes was different between infants below the 5th birth-weight centile for each chart (OR 4.47, 95% CI 3.30-6.04, p < 0.001 for the population chart; OR 5.78, 95% CI 4.22-7.91, p < 0.001 for the customised chart; OR 10.74, 95% CI 7.32-15.77, p < 0.001 for the Intergrowth chart) but similar in the smallest 5% of the population (OR 4.34, 95% CI 3.22-5.86, p < 0.001 for the population chart; OR 5.23, 95% CI 3.85-7.11, p < 0.001 for the customised chart; OR 4.69, 95% CI 3.47-6.34, p < 0.001 for the Intergrowth chart). For a fixed FPR of 10%, different thresholds for each chart achieved similar sensitivity for perinatal mortality in small infants (29% for all charts). Similar behaviour of different thresholds and similar risk/sensitivity for fixed FPR were observed in relation to other outcomes and for LGA infants. Limitations of this study include the relative homogeneity of the Swedish population, which limits generalisability to other populations; customised centiles may perform differently in populations with increased heterogeneity of ethnic background.ConclusionsThe risk of adverse outcomes was consistent across proportions of the population but did not reflect fixed thresholds, such as the 10th or 90th centiles, across different growth charts. Chart-specific thresholds for the population should be considered in clinical practice.

BackgroundThe relationship between population trends in delaying childbirth and rising rates of primary cesarean delivery is unclear. The aims of the present study were (1) to characterize the association between maternal age and the outcome of labor, (2) to determine the proportion of the increase in primary cesarean rates that could be attributed to changes in maternal age distribution, and (3) to determine whether the contractility of uterine smooth muscle (myometrium) varied with maternal age.Methods and findingsWe utilized nationally collected data from Scotland, from 1980 to 2005, and modeled the risk of emergency cesarean section among women delivering a liveborn infant in a cephalic presentation at term. We also studied isolated myometrial strips obtained from 62 women attending for planned cesarean delivery in Cambridge, England, from 2005 to 2007. Among 583,843 eligible nulliparous women, there was a linear increase in the log odds of cesarean delivery with advancing maternal age from 16 y upwards, and this increase was unaffected by adjustment for a range of maternal characteristics (adjusted odds ratio for a 5-y increase 1.49, 95% confidence interval [CI] 1.48-1.51). Increasing maternal age was also associated with a longer duration of labor (0.49 h longer for a 5-y increase in age, 95% CI 0.46-0.51) and an increased risk of operative vaginal birth (adjusted odds ratio for a 5-y increase 1.49, 95% CI 1.48-1.50). Over the period from 1980 to 2005, the cesarean delivery rate among nulliparous women more than doubled and the proportion of women aged 30-34 y increased 3-fold, the proportion aged 35-39 y increased 7-fold, and the proportion aged > or =40 y increased 10-fold. Modeling indicated that if the age distribution had stayed the same over the period of study, 38% of the additional cesarean deliveries would have been avoided. Similar associations were observed in multiparous women. When studied in vitro, increasing maternal age was associated with reduced spontaneous activity and increased likelihood of multiphasic spontaneous myometrial contractions.ConclusionsDelaying childbirth has significantly contributed to rising rates of intrapartum primary cesarean delivery. The association between increasing maternal age and the risk of intrapartum cesarean delivery is likely to have a biological basis.