The Perinatal Database of the Netherlands

The Copenhagen Primary Care Laboratory Pregnancy (CopPreg) database

PURPOSE

The Copenhagen Primary Care Laboratory Pregnancy (CopPreg) database was established based on data from The Danish Medical Birth Register and the Copenhagen Primary Care Laboratory (CopLab) database. The aim was to provide a biomedical and epidemiological data resource for research in early disease programming (eg, parental clinical biomarker levels and pregnancy/ birth outcomes or long-term health in the offspring).

PARTICIPANTS

The cohort consisted in total of 203 608 women (with 340 891 pregnancies) who gave birth to 348 248 children and with 200 590 related fathers. In this paper, we focused on women and fathers who had clinical test requisitions prior to and during pregnancy, and on all children. Thus, the cohort in focus consisted of 203 054 pregnancies with requisitions on 147 045 pregnant women, 39 815 fathers with requisitions during periconception and 65 315 children with requisitions.

FINDINGS TO DATE

In addition to information on pregnancy and birth health status and general socio-demographic data, over 2.2 million clinically relevant test results were available for pregnancies with requisitions, over 1.5 million for children and over 600 000 test results were available for the fathers with requisitions during periconception. These were ordered by general practitioners in the primary care setting only and included general blood tests, nutritional biomarkers (macronutrients and micronutrients) and hormone tests. Information on tests related to infections, allergies, heart and lung function and sperm analyses (fathers) were also available.

FUTURE PLANS

The CopPreg database provides ready to use and valid data from already collected, objectively measured and analysed clinical tests. With several research projects planned, we further invite national and international researchers to use this vast data resource. In a coming paper, we will explore and discuss the indication bias in our cohort.

Caesarean section rates in subgroups of women and perinatal outcomes

OBJECTIVES

To identify factors that are associated with a relatively low caesarean section (CS) rate by examining the CS rate in various subgroups in the Netherlands.

DESIGN

Cross-sectional analysis.

SETTINGS

the Netherlands.

POPULATION

A total of 685 452 births in the Netherlands Perinatal Registry from 2007 to 2010.

METHODS

A modified classification system for CS was used to categorise all women into ten groups. Labour management, mode of delivery, maternal and neonatal morbidity and mortality were assessed according to these ten groups.

MAIN OUTCOME MEASURES

Caesarean section, labour induction, instrumental delivery, postpartum haemorrhage, perineal laceration, duration of second stage of labour, Apgar score, fetal and neonatal mortality.

RESULTS

Total CS rate was 15.6%. Term, nulliparous and parous women with a singleton pregnancy of a fetus in cephalic position and spontaneous onset of labour had CS rates of 9.6 and 1.9% and instrumental birth rates of 19.4 and 2.4%, respectively; 17.3% of births were induced. Among women with a previous CS and term, singleton pregnancies with a fetus in cephalic presentation, 71% had trial of labour, of which 75% had a successful vaginal birth. Of women with multiple gestation, 43% had CS. Women with CS due to 'failure to progress' in the second stage of labour had a median duration of second-stage pushing of almost 2 hours in nulliparas and >90 minutes in parous women.

CONCLUSIONS

Several obstetric practice patterns may have contributed to the relatively low overall CS rate in the Netherlands: a relatively low CS rate in term, singleton pregnancies of a fetus in cephalic position and spontaneous onset of labour, relatively low rate of labour induction, a high rate of a trial of labour after a previous CS, the use of vacuum and forceps, and a high proportion of women being taken care of by midwives.

TWEETABLE ABSTRACT

The Netherlands has several practice patterns that may have contributed to its relatively low CS rate.

Trends in obstetric interventions in the Dutch obstetrical care system in the period 1993–2002

OBJECTIVE

To determine trends in induction of labour-, instrumental vaginal delivery- and caesarean section rates in the Netherlands in the period 1993-2002.

STUDY DESIGN

Data derived from The Netherlands Perinatal Registry and Statistics Netherlands were used to calculate annual rates for induction of labour, instrumental vaginal delivery and caesarean section. Regarding caesarean section, rates were also calculated for different subgroups with respect to parity, presentation of the fetus, gestational age and multiple pregnancies. In the subgroup of women with a singleton fetus in vertex presentation between 37 and 42 weeks of gestation instrumental delivery rates were compared for women with induced labours and women in spontaneous labour.

RESULTS

The overall CS rate rose from 8.1 to 13.6%. Proportionally the rise was greatest for breech presentation (+37.7%), multiple gestations (+12.7%) and women delivering between 24 and 28 weeks (+9.5%). However, in absolute numbers the rise was most impressive in the group of women with a singleton fetus in vertex presentation between 37 and 42 weeks of gestation. Rate of induction of labour and instrumental vaginal delivery remained constant (approximately 15% respectively 10% of all deliveries). In nulliparous term women with singletons in vertex presentation the CS rate increased with 8.0% to a rate of 20.7% when labour was induced versus an increase of 3.4% to a rate of 7.5% in spontaneous labour.

CONCLUSION

In absolute numbers the rise in CS was most extensive in the group of women with a singleton fetus in vertex presentation between 37 and 42 weeks of gestation. Induction of labour rates and instrumental vaginal delivery rates remained constant during the past decade.

Sistemas de informação e mortalidade perinatal: conceitos e condições de uso em estudos epidemiológicos

O monitoramento da mortalidade perinatal depende da qualidade dos dados dos sistemas de informação. As diferentes definições para a notificação e cálculo da mortalidade perinatal podem afetar a magnitude e análise dos seus componentes. Comparou-se a disponibilidade de informações sobre nascidos vivos, óbitos fetais e neonatais precoces no Registro Civil, SIM e SINASC para oito unidades da federação com cobertura de eventos acima de 90%, em 2002. Verificou-se que o SINASC apresenta maior cobertura de eventos que o registro civil e excelente completude de dados (superior a 99%). O SIM apresenta situação distinta, há elevada ausência de informação sobre peso ao nascer (23,4%), idade gestacional (9,1%), idade da mãe (18,5%), tipo de gravidez (13,8%) e anos de estudo da mãe (40,6%), para os óbitos fetais. Os óbitos neonatais precoces apresentam comportamento semelhante, com ausência do registro do peso ao nascer em 22,6%, idade gestacional (17,8%), tipo de gravidez (19,1%), idade (27,9%) e escolaridade da mãe (38,5%). Não foi possível caracterizar se os óbitos fetais eram intra-parto ou ante-parto por falta de informação. No entanto, estes dados poderiam ser facilmente obtidos, pois mais de 95% dos eventos ocorreram em estabelecimentos hospitalares. Os critérios para notificação de óbitos fetais e nascidos vivos nos sistemas de informação dificultam a comparação internacional da magnitude e da participação de seus componentes da mortalidade perinatal. A ausência de informações compromete a obtenção de indicadores específicos, dificultando as atividades de monitoramento. Algumas atividades são indicadas para o aprimoramento do SIM.

Membrane sweeping and prevention of post-term pregnancy in low-risk pregnancies: a randomised controlled trial

OBJECTIVE

To evaluate the effectiveness of membrane sweeping at 41 weeks for the prevention of post-term pregnancy.

DESIGN

A multicentre randomised controlled trial.

SETTING

Fifty-one primary care midwifery practices in the Netherlands.

POPULATION

A total of 742 low-risk pregnant women at 41 weeks of gestation.

METHODS

Participants were randomly assigned to serial sweeping of the membranes (every 48 hours until labour commenced up to 42 weeks of gestation) or no intervention.

MAIN OUTCOME MEASURES

Post-term pregnancy (>or=42 weeks). Subgroup analyses were performed on nulliparous and parous women. Secondary outcomes included adverse effects.

RESULTS

Serial sweeping of the membranes at 41 weeks decreased the risk of post-term pregnancy (87/375 [23%] versus 149/367 [41%]; relative risk [RR] 0.57, 95% CI 0.46-0.71; number needed to treat [NNT] 6 [95% CI 4-9]). Benefits were also seen in both subgroups (nulliparous: 57/198 [29%] versus 89/192 [46%]; RR 0.62 [95% CI 0.48-0.81]; NNT 6 [95% CI 4-12] and parous: 30/177 [17%] versus 60/175 [34%]; RR 0.49 [95% CI 0.34-0.73]; NNT 6 [95% CI 4-6]). Adverse effects were similar in both the groups except for uncomplicated bleeding, which was reported more frequently in the sweeping group. Other obstetric outcomes and indicators of neonatal morbidity were similar in both groups. There were two perinatal deaths in each group.

CONCLUSIONS

Membrane sweeping at 41 weeks can substantially reduce the proportion of women with post-term pregnancy.

The effect of the Term Breech Trial on medical intervention behaviour and neonatal outcome in The Netherlands: an analysis of 35,453 term breech infants

OBJECTIVE

To examine the effects of the Term Breech Trial on the medical behaviour of Dutch obstetricians and on neonatal outcomes.

DESIGN

Retrospective observational study.

SETTING

The Netherlands.

POPULATION

Infants born at term in breech presentation in the Netherlands between 1998 and 2002, with birthweights < or =4000 g (n= 33,024) and >4000 g (n= 2429), respectively. Multiple pregnancies, antenatal death and major congenital malformations were excluded.

METHODS

Data derived from the Dutch Perinatal Database were used to compare modes of delivery and neonatal outcome of infants born in breech position in the 33 months preceding publication of the Term Breech Trial and in the 25 months thereafter.

MAIN OUTCOME MEASURES

Incidence of planned and emergency caesarean section, vaginal breech delivery, perinatal death, 5-minute Apgar score and birth trauma.

RESULTS

Within two months after publication of the Term Breech Trial, the overall caesarean rate increased from 50% to 80% and has remained stable thereafter. In the group of infants < or =4000 g, this was associated with a significant decrease of perinatal mortality from 0.35% to 0.18%, a decrease of the incidence of a 5-minute Apgar score <7 from 2.4% to 1.1% and a decrease of birth trauma from 0.29% to 0.08%. In the (small) group of infants >4000 g, a similar trend was observed.

CONCLUSIONS

The Term Breech Trial has resulted in an exceptionally rapid change in medical behaviour by Dutch obstetricians. This change was followed by improved neonatal outcome.

Risk of complications of pregnancy in women with type 1 diabetes: nationwide prospective study in the Netherlands

OBJECTIVE

To investigate maternal, perinatal, and neonatal outcomes of pregnancies in women with type 1 diabetes in the Netherlands.

DESIGN

Nationwide prospective cohort study.

SETTING

All 118 hospitals in the Netherlands.

PARTICIPANTS

323 women with type 1 diabetes who became pregnant between 1 April 1999 and 1 April 2000.

MAIN OUTCOME MEASURES

Maternal, perinatal, and neonatal outcomes of pregnancy.

RESULTS

84% (n = 271) of the pregnancies were planned. Glycaemic control early in pregnancy was good in most women (HbA(1c) < or = 7.0% in 75% (n = 212) of the population), and folic acid supplementation was adequate in 70% (n = 226). 314 pregnancies that went beyond 24 weeks' gestation resulted in 324 infants. The rates of pre-eclampsia (40; 12.7%), preterm delivery (101; 32.2%), caesarean section (139; 44.3%), maternal mortality (2; 0.6%), congenital malformations (29; 8.8%), perinatal mortality (9; 2.8%), and macrosomia (146; 45.1%) were considerably higher than in the general population. Neonatal morbidity (one or more complications) was extremely high (260; 80.2%). The incidence of major congenital malformations was significantly lower in planned pregnancies than in unplanned pregnancies (4.2% (n = 11) v 12.2% (n = 6); relative risk 0.34, 95% confidence interval 0.13 to 0.88).

CONCLUSION

Despite a high frequency of planned pregnancies, resulting in overall good glycaemic control (early) in pregnancy and a high rate of adequate use of folic acid, maternal and perinatal complications were still increased in women with type 1 diabetes. Neonatal morbidity, especially hypoglycaemia, was also extremely high. Near optimal maternal glycaemic control (HbA1c < or = 7.0%) apparently is not good enough.

Fundamental classification of perinatal death. Validation of a new classification system of perinatal death

OBJECTIVE

To validate a newly introduced classification system for the registration of perinatal mortality.

DESIGN

Descriptive.

SETTING

Dutch Healthcare region Delft-Westland-Oostland (DWO).

MATERIAL AND METHODS

In a 10-years period (1983-1992), all cases of perinatal death with a birthweight above 500 g (n=239) were included into the study. Six assessors: four gynaecologists and two paediatricians were asked to classify all cases using a classification model proposed by the authors. This model is based on the underlying cause of death using simple principles of obstetrical and neonatal pathology: birth trauma, infection, placenta or cord pathology, pathology of immune tolerance of mother and fetus, congenital malformation of the fetus and complications of a pre-viable delivery. Therefore, we used the term fundamental classification. The six assessors worked independently of each other in classifying all cases of perinatal death, were not involved in the original development of the system and were unaware of the results of the classification of their colleagues. Agreement beyond chance between assessors was calculated using kappa's coefficient for multiple observers and multiple test results.

RESULTS

Overall kappa was 0.70 (95% confidence interval (C.I.) 0.68-0.72). Reproducibility was poor for the categories trauma and unclassifiable, fair for the categories infections and placental/cord pathology, and very good to excellent for the categories maternal immune system pathology, congenital malformations and complications of prematurity.

CONCLUSIONS

The proposed system showed a good level of agreement and appeared to be simply applicable. It offers a good insight in the underlying cause of death with the possibility for recognising preventive factors in future pregnancies and will enable (inter)national comparisons in causes of perinatal death. A reliable uniform registration of perinatal death based on the underlying causes should be the basis for improvement of the quality of perinatal care.

Randomised clinical trial on the effect of the Dutch obstetric peer review system

The project "Obstetric Peer Review Interventions" (Verloskundige Onderlinge Kwaliteitsspiegeling Interventies, VOKSINT) was set-up in The Netherlands in 1994. It provided annual comparison data (quality ranking, league tables) for secondary care obstetric departments adjusted for population differences, based on the data registered in the Perinatal Database of The Netherlands (Landelijke Verloskunde Registratie, LVR). The aim of the so-called VOKS reports was to influence obstetricians' interventions in such a way that they led to a more homogeneous policy. To assess this influence, a trial was set-up, with departments randomly assigned to be or not to be informed about the VOKS results. Obstetric intervention rates and the morbidity of newborns including neonatal neurological examinations (NNEs) were assessed. Obstetric intervention rates were similar in the report group and the control group. Practice in the report group became more homogeneous (adjusted for population differences) than in the control departments, but this was only statistically significant for term caesarean section.