Re: Maternal and fetal risk factors for stillbirth: population based study
In a population based observation study, it is suggested that improving the detection of intrauterine growth restriction (essentially by using the GROW software, developed by Jason Gardosi) could lead to 600 fewer stillbirths each year in the UK [2].
Whilst it certainly is the case that results from this observational study show that infants identified as having fetal growth restriction antenatally have a reduced risk of stillbirth (compared to those detected antenatally), observational evidence cannot replace robust randomised evidence. The DIGITAT [1] randomised equivalence trial in 321 women showed that, for singleton term pregnancies, with suspected intrauterine growth restriction, that induction had no impact on the composite outcome (death, APGAR <7, umbilical artery pH < 7.05 or admission to ICU). Whilst effects might be different at preterm weeks, randomised evidence of early prompt diagnosis and active surveillance is needed [3].
It is also claimed that the risk factors of maternal obesity, smoking and intrauterine growth restriction explain the “majority” of the normally formed stillbirths. Yet, to make such a claim the percentage of variation explained or some measure of discrimination (area under receiver operating curve) or calibration should be evaluated. This paper therefore does not inform whether these identified risk factors can predict the majority of stillbirths.
The software GROW might be able to identify infants with intrauterine growth restriction, but there will certainly be some miss-diagnoses; that is identification of fetuses as having fetal growth restriction which are actually growing appropriately. In the extreme case, surveillance and monitoring of fetuses with suspected intrauterine growth restriction might lead to induction; which in the case of miss-diagnoses will be at the risk of harm.
Whether 600 stillbirths could be avoided each year in the UK, by improving the detection of fetuses with intrauterine growth restriction, by essentially using the software GROW is debatable. Randomised evidence at term seems to suggest that induction in such cases will not necessarily be of benefit. Maybe it is time we had randomised controlled trials of GROW to determine whether it can live up to its claims. Trials would need to be very large to detect small effect sizes, perhaps prohibitively so, but if effect sizes are as large as suggested here, then such trials might well be feasible.
[2] Gardosi J, Madurasinghe V, Williams M, Malik A, Francis A. Maternal and fetal risk factors for stillbirth: population based study. BMJ. 2013 Jan 24;346:f108. doi: 10.1136/bmj.f108.
[1] van Wyk L, Boers KE, van der Post JAM, et al. Effects on (neuro)developmental and behavioral outcome at 2 years of age of induced labor compared with expectant management in intrauterine growth-restricted infants: long-term outcomes of the DIGITAT trial. Am J Obstet Gynecol 2012;206:406.e1-7.
[3] Grivell RM, Wong L, Bhatia V.Regimens of fetal surveillance for impaired fetal growth. Cochrane Database Syst Rev. 2012 Jun 13;6:CD007113. doi: 10.1002/14651858.CD007113.pub3.
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Re: Maternal and fetal risk factors for stillbirth: population based study
In a population based observation study, it is suggested that improving the detection of intrauterine growth restriction (essentially by using the GROW software, developed by Jason Gardosi) could lead to 600 fewer stillbirths each year in the UK [2].
Whilst it certainly is the case that results from this observational study show that infants identified as having fetal growth restriction antenatally have a reduced risk of stillbirth (compared to those detected antenatally), observational evidence cannot replace robust randomised evidence. The DIGITAT [1] randomised equivalence trial in 321 women showed that, for singleton term pregnancies, with suspected intrauterine growth restriction, that induction had no impact on the composite outcome (death, APGAR <7, umbilical artery pH < 7.05 or admission to ICU). Whilst effects might be different at preterm weeks, randomised evidence of early prompt diagnosis and active surveillance is needed [3].
It is also claimed that the risk factors of maternal obesity, smoking and intrauterine growth restriction explain the “majority” of the normally formed stillbirths. Yet, to make such a claim the percentage of variation explained or some measure of discrimination (area under receiver operating curve) or calibration should be evaluated. This paper therefore does not inform whether these identified risk factors can predict the majority of stillbirths.
The software GROW might be able to identify infants with intrauterine growth restriction, but there will certainly be some miss-diagnoses; that is identification of fetuses as having fetal growth restriction which are actually growing appropriately. In the extreme case, surveillance and monitoring of fetuses with suspected intrauterine growth restriction might lead to induction; which in the case of miss-diagnoses will be at the risk of harm.
Whether 600 stillbirths could be avoided each year in the UK, by improving the detection of fetuses with intrauterine growth restriction, by essentially using the software GROW is debatable. Randomised evidence at term seems to suggest that induction in such cases will not necessarily be of benefit. Maybe it is time we had randomised controlled trials of GROW to determine whether it can live up to its claims. Trials would need to be very large to detect small effect sizes, perhaps prohibitively so, but if effect sizes are as large as suggested here, then such trials might well be feasible.
[2] Gardosi J, Madurasinghe V, Williams M, Malik A, Francis A. Maternal and fetal risk factors for stillbirth: population based study. BMJ. 2013 Jan 24;346:f108. doi: 10.1136/bmj.f108.
[1] van Wyk L, Boers KE, van der Post JAM, et al. Effects on (neuro)developmental and behavioral outcome at 2 years of age of induced labor compared with expectant management in intrauterine growth-restricted infants: long-term outcomes of the DIGITAT trial. Am J Obstet Gynecol 2012;206:406.e1-7.
[3] Grivell RM, Wong L, Bhatia V.Regimens of fetal surveillance for impaired fetal growth. Cochrane Database Syst Rev. 2012 Jun 13;6:CD007113. doi: 10.1002/14651858.CD007113.pub3.
Competing interests: No competing interests