Association Between Iatrogenic Delivery for Suspected Fetal Growth Restriction and Childhood School Outcomes.

Importance: Timely delivery of infants suspected of having fetal growth restriction (FGR) is a balance between preventing stillbirth and minimizing prematurity, particularly because many infants with suspected FGR have normal growth. Objective: To explore the association between iatrogenic delivery for suspected FGR and childhood school outcomes. Design, Setting, and Participants: A retrospective whole-population cohort study linking perinatal data from births 32 weeks' or more gestation between January 1, 2003, to December 31, 2013, to developmental and educational test scores at preparatory school, and at school grades 3, 5, and 7 in Victoria, Australia. Follow-up was concluded in 2019. Exposures: Suspicion or nonsuspicion of FGR, presence or absence of iatrogenic delivery (defined as early induction of labor or cesarean delivery prior to labor) for suspected FGR, and presence or absence of small for gestational age (SGA). Main Outcomes and Measures: The coprimary outcomes were being in the bottom 10th percentile on 2 or more of 5 developmental domains at school entry and being below the national minimum standard on 2 or more of 5 educational domains in grades 3, 5, or 7. Results: In the birth population of 705 937 infants, the mean gestation at birth was 39.1 (SD, 1.5) weeks and the mean birth weight was 3426 (SD, 517) grams. The birth population linked to 181 902 children with developmental results and 425 717 children with educational results. Compared with infants with severe SGA (birth weight <3rd percentile) not suspected of having FGR, infants with severe SGA delivered for suspected FGR were born earlier (mean gestation, 37.9 weeks vs 39.4 weeks). They also had a significantly increased risk of poor developmental outcome at school entry (16.2% vs 12.7%; absolute difference, 3.5% [95% CI, 0.5%-6.5%]); adjusted odds ratio [aOR], 1.36 [95% CI, 1.07-1.74]) and poor educational outcomes in grades 3, 5, and 7 (for example, in grade 7: 13.4% vs 10.5%; absolute difference, 2.9% [95% CI, 0.4%-5.5%]); aOR, 1.33 [95% CI, 1.04-1.70]). There was no significant difference between infants with normal growth (birth weight ≥10th percentile) delivered for suspected FGR and those not suspected of having FGR in developmental outcome (8.6% vs 8.1%; absolute difference, 0.5% [95% CI, -1.1% to 2.0%]); aOR, 1.17 [95% CI, 0.95-1.45]) or educational outcome in grade 3, 5 or 7, despite being born earlier (mean gestation, 38.0 weeks vs 39.1 weeks). Conclusions and Relevance: In this exploratory study conducted in Victoria, Australia, iatrogenic delivery of infants with severe SGA due to suspected FGR was associated with poorer school outcomes compared with infants with severe SGA not suspected of having FGR. Iatrogenic delivery of infants with normal growth due to suspected FGR was not associated with poorer school outcomes compared with infants with normal growth not suspected of having FGR.

The pitfalls of using birthweight centile charts to audit care.

OBJECTIVES: Timely delivery of fetal growth restriction (FGR) is important in reducing stillbirth. However, targeted earlier delivery of FGR preferentially removes smaller babies from later gestations, thereby right-shifting the distribution of birthweights at term. This artificially increases the birthweight cutoffs defining the lower centiles and redefines normally grown babies as small by population-based birthweight centiles. Our objective was to compare updated Australian national population-based birthweight centile charts over time with the prescriptive INTERGROWTH-21st standard. METHODS: A retrospective descriptive study of all singleton births ≥34 weeks' gestation in Victoria, Australia in five two-year epochs: 1983-84, 1993-94, 2003-04, 2013-14, and 2016-17. The birthweight cutoffs defining the 3rd and 10th centile from three Australian national population-based birthweight centile charts, for births in 1991-1994, in 1998-2007, and 2004-2013 respectively, were applied to each epoch to calculate the proportion of babies with birthweight <3rd and <10th centile. The same analysis was done using the INTERGROWTH-21st birthweight standard. To assess change over gestation, proportions were also calculated at preterm, early term and late term gestations. RESULTS: From 1983-84 to 2016-17, the proportion of babies with birthweight <3rd fell across all birthweight centile charts, from 3.1% to 1.7% using the oldest Australian chart, from 3.9% to 1.9% using the second oldest Australian chart, from 4.3% to 2.2% using the most recent Australian chart, and from 2.0% to 0.9% using the INTERGROWTH-21st standard. A similar effect was evident for the <10th centile. The effect was most obvious at term gestations. Updating the Australian population birthweight chart progressively right-shifted the birthweight distribution, changing the definition of small over time. The birthweight distribution of INTERGROWTH-21st was left-shifted compared to the Australian charts. CONCLUSIONS: Locally-derived population-based birthweight centiles are better for clinical audit of care but should not be updated. Prescriptive birthweight standards are less useful in defining 'small' due to their significant left-shift.

Risk factor assessment for fetal growth restriction, are we providing best care?

Serial third trimester ultrasound examinations for fetal biometry are recommended for women with risk factors of fetal growth restriction (FGR). We conducted a retrospective cohort study on all singleton births in Victoria from 2009 to 2017 to assess how many women with major risk factors for FGR had serial third trimester biometry. Only 19.5% of women with at least one major risk factor for FGR had evidence of serial third trimester ultrasound assessments. The development and implementation of a state-wide or nationwide guideline for early pregnancy risk factor assessment in FGR may be beneficial.