Background incidence rates of adverse pregnancy outcomes in the Netherlands: Data of 2006-2018.

OBJECTIVE: Maternal vaccination is an effective and safe intervention to protect newborns against infectious diseases shortly after birth. We assessed background rates of adverse pregnancy outcomes before the implementation of a maternal pertussis immunisation programme in the Netherlands, to put into perspective the safety concerns about such outcomes following immunisation. STUDY DESIGN: In this retrospective cross-sectional study, annual numbers of pregnancy outcomes derived from the Dutch Perinatal Registry were used to calculate incidence rates per 10,000 in the 2006-2018 period. Births of ≥500 g birth weight and ≥24 + 0 w gestational age were included. Trends with moving-average-lines over the past 3 years were plotted, with 95 % confidence interval. RESULTS: From 2006 through 2018, yearly numbers of pregnancies ranged between 158,868-175,710. Numbers of newborns ranged between 161,307-178,874, of whom 160,838-178,177 were live-born. Most outcomes were stable over time. Between 2006-2011, occurrence of labour induction increased by 68 %, and postpartum hemorrhage increased by 25 %. Both stabilised from 2011 onwards. Perinatal mortality up to day 7 or 28 postpartum decreased by 38 % and 37 %, respectively. Occurrence of low Apgar score among preterm infants born before 37 + 0 w gestational age and among term infants increased by 19 % and 27 %, respectively. CONCLUSION: Our study on background incidences showed notable increases over time in occurrence of labour induction, postpartum hemorrhage and low Apgar score, while showing a considerable decrease in overall perinatal mortality. These findings should be considered when interpreting data on adverse events occurring since the maternal pertussis immunisation programme was implemented.

Risk Factors for Retinopathy of Prematurity in the Netherlands: A Comparison of Two Cohorts.

INTRODUCTION: Retinopathy of prematurity (ROP) remains an important cause for preventable blindness. Aside from gestational age (GA) and birth weight, risk factor assessment can be important for determination of infants at risk of (severe) ROP. METHODS: Prospective, multivariable risk-analysis study (NEDROP-2) was conducted, including all infants born in 2017 in the Netherlands considered eligible for ROP screening by pediatricians. Ophthalmologists provided data of screened infants, which were combined with risk factors from the national perinatal database (Perined). Clinical data and potential risk factors were compared to the first national ROP inventory (NEDROP-1, 2009). During the second period, more strict risk factor-based screening inclusion criteria were applied. RESULTS: Of 1,287 eligible infants, 933 (72.5%) were screened for ROP and matched with the Perined data. Any ROP was found in 264 infants (28.3% of screened population, 2009: 21.9%) and severe ROP (sROP) (stage ≥3) in 41 infants (4.4%, 2009: 2.1%). The risk for any ROP is decreased with a higher GA (odds ratio [OR] 0.59 and 95% confidence interval [CI] 0.54-0.66) and increased for small for GA (SGA) (1.73, 1.11-2.62), mechanical ventilation >7 days (2.13, 1.35-3.37) and postnatal corticosteroids (2.57, 1.44-4.66). For sROP, significant factors were GA (OR 0.37 and CI 0.27-0.50), SGA (OR 5.65 and CI 2.17-14.92), postnatal corticosteroids (OR 3.81 and CI 1.72-8.40), and perforated necrotizing enterocolitis (OR 7.55 and CI 2.29-24.48). CONCLUSION: In the Netherlands, sROP was diagnosed more frequently since 2009. No new risk factors for ROP were determined in the present study, apart from those already included in the current screening guideline.

Semantic Cross-Mapping Execution of Data in the Perinatal Registry of the Netherlands.

INTRODUCTION: The electronically submitted data from midwives and hospitals to the Netherlands perinatal registry vary significantly in their data definitions, and electronic message versions. The purpose of this article is to describe the semantic cross-mapping tool and execution procedure to prepare the data for statistical analysis. METHODS: requirements analysis, design, development and testing. RESULTS: The tool for governance of versions of datasets, CIMs, data, and value sets is designed, developed, and tested. The test is based on the data-mart of version PRN 1.3 based data from 2019. Data are semantically cross mapped to current version perinatology data 2.2. CONCLUSION: The cross-mapping of PRN 1.3 data to perinatology 2.2 data are defined in the tool, testing revealed this mapping is successful.

Hypertensive Complications of Pregnancy and Risk of Venous Thromboembolism.

Hypertension during pregnancy and preeclampsia are associated with increased arterial thrombotic risk in later life. Whether these complications are associated with risk of venous thromboembolism (VTE) on the short term after pregnancy and on the long term, that is, outside pregnancy, is largely unknown. We conducted a nationwide cohort study in women with at least 1 pregnancy and their first VTE risk by linking the Dutch perinatal registry (Perined) to anticoagulation clinics. We used Cox proportional hazard models to estimate hazard ratios (HRs) and corresponding 95% CI for VTE risk in women with hypertension during pregnancy, women with preeclampsia, compared with women with uncomplicated pregnancies (reference). A total of 1 919 918 women were followed for a median of 13.7 (interquartile range, 7.6-19.2) years for a total of 24 531 118 person-years in which 5759 first VTEs occurred; incidence rate: 2.3 (95% CI, 2.3-2.4) per 10 000 person-years. In the first pregnancy and 3-month postpartum period, VTE risk was higher in women with hypertension, HR, 2.0 (95% CI, 1.7-2.4), and highest among women with preeclampsia, HR, 7.8 (95% CI, 5.4-11.3), versus the reference group. On the long term, women with hypertension during pregnancy and preeclampsia had a higher VTE risk: HR, 1.5 (95% CI, 1.4-1.6) and HR, 2.1 (95% CI, 1.8-2.4), respectively, versus the reference group. When excluding events during pregnancy and postpartum, these HRs were 1.4 (95% CI, 1.3-1.5) and 1.6 (95% CI, 1.4-2.0), respectively. In conclusion, hypertension during pregnancy and preeclampsia are associated with an increased VTE risk during pregnancy and postpartum period and in the 13 years after.