Too early to question effectiveness of Dutch maternity care system
With interest we read the study from Evers et al. on perinatal
mortality and morbidity in the Utrecht region, one of the 12 provinces in
the Netherlands. This is the first study ever to show a higher mortality
rate among births that started in primary care compared with secondary
care. We have concerns about the methods used.
First, although the title suggests that this is a prospective cohort
study, the entire population at risk has been defined retrospectively and
was based on postal codes of the catchment area of one university
hospital. All intrapartum and neonatal deaths were included from hospitals
and midwifery practices within this area, but potentially not all births.
Midwives in practices at the periphery of the catchment area will also
care for many women in neighbouring regions. These births have not been
included in the study, unless the baby died. This will artificially
inflate mortality rates in midwifery practices.
Second, the study was conducted in only one region in the
Netherlands. The intrapartum and neonatal mortality rate was twice as high
as in recent national studies among women in primary care at the onset of
labour (1.39 versus 0.65 and 0.52 per 1000)1;2. Although classification
bias and underreporting may have played a role in these retrospective
studies, it is unlikely that half of all deaths would have been missed. In
another prospective study of perinatal mortality cases only 3.5%
additional cases were found as compared to national registration data 3.
Strikingly, in Evers' study 67% of all babies that died during labour
were born in primary care. This means that either the midwife noticed
fetal distress too late to refer a woman because the birth was imminent or
a deceased baby was born so fast that the midwife arrived too late to a
woman's home. It is very surprising that these situations were much more
common than referral before birth. In Amelink's national study, only 5% of
intrapartum deaths were among births that took place in primary care 1.
This discrepancy suggests that the study sample may be rather different
from the national population.
Given the limitations of the study, the conclusion that labour
starting in primary care carries a higher risk of delivery related
perinatal death compared to labour starting in secondary care is premature
from a scientific point of view. The authors correctly state that "their
findings are unexpected and deserve further evaluation". Previous audit
studies did not find that features of the Dutch maternity care system were
related to preventable perinatal deaths 3;4. The results of Evers' study
call for an urgent review of all mortality cases in the audit study
announced by the authors. In addition, perinatal outcomes in other regions
need to be examined. Ideally, a large national prospective cohort study
should be conducted.
The suggestion that "the obstetric care system in the Netherlands possibly
contributes to the high perinatal mortality rate" can not be made based on
these data alone.
(1) Amelink-Verburg MP, Verloove-Vanhorick SP, Hakkenberg RM,
Veldhuijzen IM, Bennebroek GJ, Buitendijk SE. Evaluation of 280,000 cases
in Dutch midwifery practices: a descriptive study. BJOG 2008; 115(5):570-
(2) De Jonge A, Van der Goes BY, Ravelli AC, Amelink-Verburg MP, Mol BW,
Nijhuis JG et al. Perinatal mortality and morbidity in a nationwide cohort
of 529,688 low-risk planned home and hospital births. BJOG 2009;
(3) Wolleswinkel-van den Bosch JH, Vredevoogd CB, Borkent-Polet M, van
EJ, Fetter WP, Lagro-Janssen TL et al. Substandard factors in perinatal
care in The Netherlands: a regional audit of perinatal deaths. Acta Obstet
Gynecol Scand 2002; 81(1):17-24.
(4) Bais JM, Eskes M, Bonsel GJ. [The determinants of the high Dutch
perinatal mortality in a complete regional cohort, 1990-1994]. Ned
Tijdschr Geneeskd 2004; 148(38):1873-1878.