Perinatal mortality and severe morbidity in low and high risk term pregnancies in the Netherlands: prospective cohort study

Too early to question effectiveness of Dutch maternity care system

3 November 2010

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- 578.

(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; 116(9):1177-1184.

(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.

Competing interests: None declared

Ank De Jonge, senior midwife researcher

Ben Willem Mol, Birgit Y Van der Goes, Jan G Nijhuis, Joris A Van der Post, Simone E Buitendijk

Midwifery Science, AVAG and the EMGO Institute for Health and Care Research, VU University Medical C

Click to like: