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• Lack of reliable data confuses discussion on safety of midwife-led and obstetrician-led care
  Ank De Jonge, Francois Schellevis
  Published on: 11 January 2018

• Published on: 11 January 2018

  Lack of reliable data confuses discussion on safety of midwife-led and obstetrician-led care

  • Ank De Jonge, Associate professor Midwifery Science Department of Midwifery Science AVAG/ Amsterdam Public Health research institute VU University Medical Center Amsterdam.
  • Other Contributors:
    • Francois Schellevis, Professor of General Practice

  With interest we read the article of Wiegerinck et al. on intrapartum and neonatal mortality among low-risk women in midwife-led versus obstetrician-led care based on case notes and data from the Dutch national perinatal database (PRN, nowadays called ‘Perined’). In a recent commentary we addressed some important pitfalls associated with the use of register-based data.1 Although the authors acknowledge the methodological challenges of their study, and the limitations of the Perined database, it is important to specify these issues in more detail. Secondly, we want to challenge the interpretation of the findings.
  In this study clinical information regarding the women and babies in the numerators and denominators for intrapartum and neonatal mortality rates were derived from different sources. For the numerators information on women and their babies who died was taken from case notes. For the denominators information was taken from the Perined database, in which information on risk factors is often missing. The authors show in their supplementary file that in a sample of 100 women who started labour in obstetrician-led care no information was recorded for 13% of women on one or more of the eight risk factors which were defined as exclusion criteria in this study. Most women with risk factors will have been removed from the numerator, because information was available in their case notes. On the other hand, an unknown number of women with risk factors were not removed f...

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  With interest we read the article of Wiegerinck et al. on intrapartum and neonatal mortality among low-risk women in midwife-led versus obstetrician-led care based on case notes and data from the Dutch national perinatal database (PRN, nowadays called ‘Perined’). In a recent commentary we addressed some important pitfalls associated with the use of register-based data.1 Although the authors acknowledge the methodological challenges of their study, and the limitations of the Perined database, it is important to specify these issues in more detail. Secondly, we want to challenge the interpretation of the findings.
  In this study clinical information regarding the women and babies in the numerators and denominators for intrapartum and neonatal mortality rates were derived from different sources. For the numerators information on women and their babies who died was taken from case notes. For the denominators information was taken from the Perined database, in which information on risk factors is often missing. The authors show in their supplementary file that in a sample of 100 women who started labour in obstetrician-led care no information was recorded for 13% of women on one or more of the eight risk factors which were defined as exclusion criteria in this study. Most women with risk factors will have been removed from the numerator, because information was available in their case notes. On the other hand, an unknown number of women with risk factors were not removed from the denominator, because this information was missing in the Perined database. Therefore, the real mortality rate might be higher than what has been reported. Moreover, 12% of the 100 women in obstetrician-led care, according to the Perined database, had started labour in midwife-led care which indicates another potential problem with the size of the denominator. The authors controlled for differences in characteristics between the women in midwife-led and obstetrician-led care using a propensity score matched (PSM) pairs analysis. Unfortunately, this does not solve the problems with the data as no correction can be made for risk factors for which information is not available or incorrect.
  We conclude that the pitfalls regarding the definition of the study population (numerator and denominator) and the composition of the comparison groups were not taken into account sufficiently in this article. These methodological issues add to the limitations of this study.
  In addition to these limitations, the authors hypothesize that the continuous presence of an obstetric care provider and continuous CTG monitoring are important determinants of the non-significant difference found in intrapartum and neonatal mortality rates. This hypothesis is contrary to the international concern about high intervention rates without evidence of benefits.2,3 In particular, routine continuous electronic fetal monitoring and the routine involvement of obstetricians in the care of women with a normal course of pregnancy have not been recommended for improvement of perinatal results.3
  Continuous electronic fetal monitoring has not been shown to lead to better long term neonatal outcomes and is associated with a higher rate of caesarean section.4 This study showed a 3.5 fold lower CS rate among women who started labour in midwife-led care. In addition, lower rates of instrumental vaginal birth, epidural anaesthesia, episiotomy, manual removal of placenta and postpartum haemorrhage were found among these women. These findings, although statistically highly significant, should also be interpreted with caution, in view of the limitations of the data. Nevertheless, a discussion of the adverse consequences of caesarean sections and other interventions would have been appropriate. CS is associated, for example, with higher rates of severe adverse maternal morbidity5 and higher rates of unexplained stillbirth6 or uterine rupture during the next pregnancy.7
  It is important to balance the use of life-saving obstetric interventions among women who need them, while avoiding adverse effects of inappropriate use. Research findings can help professionals to make evidence-based decisions about when to offer women interventions and specialist obstetric care. However, we postulated earlier that it is not possible to reliably compare low-risk women who started labour in midwife-led versus obstetrician-led care in the Netherlands on the basis of Perined data.1 This work of Wiegerinck et al did not change our opinion and underlines the need for improving the quality of the data. If data are unreliable, findings only confuse the debate on the safety of midwife-led and obstetrician-led care.

  References
  1. De Jonge A, etal. Pitfalls in the use of register-based data for
  comparing adverse maternal and perinatal outcomes in different birth settings.
  BJOG. 2017 Sep;124(10):1477-1480.
  2. Renfrew MJ, etal. Midwifery and quality care: findings from a new evidence-informed framework for maternal and newborn care. Lancet. 2014 Sep 20;384(9948):1129-45.
  3. Miller S, etal. Beyond too little, too late and too much, too soon: a pathway towards evidence-based,
  respectful maternity care worldwide. Lancet. 2016 Oct 29;388(10056):2176-2192.
  4. Alfirevic Z, etal. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev. 2017 Feb 3;2:CD006066.
  5. Van Dillen J, etal. Severe acute maternal morbidity and mode of delivery in the Netherlands. Acta Obstet Gynecol Scand. 2010 Nov;89(11):1460-5.
  6. Moraitis AA, etal. Previous caesarean delivery and the risk of unexplained stillbirth: retrospective cohort study and meta-analysis. BJOG. 2015 Oct;122(11):1467-74.
  7. Kok N, etal. Risk of maternal and neonatal complications in subsequent pregnancy after planned
  caesarean section in a first birth, compared with emergency caesarean section: a
  nationwide comparative cohort study. BJOG. 2014 Jan;121(2):216-23.

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  Conflict of Interest:
  None declared.

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