Gouke J. Bonsel

Late start of antenatal care among ethnic minorities in a large cohort of pregnant women

Objectives  The objectives of this study were to investigate the difference in timing of the first antenatal visit between ethnic groups and to explore the contribution of several noneconomic risk factors.

Effect of screening for red cell antibodies, other than anti‐D, to detect hemolytic disease of the fetus and newborn: a population study in the Netherlands

BACKGROUND: Hemolytic disease of the fetus and newborn (HDFN) is a severe disease, resulting from maternal red cell (RBC) alloantibodies directed against fetal RBCs. The effect of a first‐trimester antibody screening program on the timely detection of HDFN caused by antibodies other than anti‐D was evaluated.

Results from simulated data sets: probabilistic record linkage outperforms deterministic record linkage

OBJECTIVE To gain insight into the performance of deterministic record linkage (DRL) vs. probabilistic record linkage (PRL) strategies under different conditions by varying the frequency of registration errors and the amount of discriminating power. STUDY DESIGN AND SETTING A simulation study in which data characteristics were varied to create a range of realistic linkage scenarios. For each scenario, we compared the number of misclassifications (number of false nonlinks and false links) made by the different linking strategies: deterministic full, deterministic N-1, and probabilistic. RESULTS The full deterministic strategy produced the lowest number of false positive links but at the expense of missing considerable numbers of matches dependent on the error rate of the linking variables. The probabilistic strategy outperformed the deterministic strategy (full or N-1) across all scenarios. A deterministic strategy can match the performance of a probabilistic approach providing that the decision about which disagreements should be tolerated is made correctly. This requires a priori knowledge about the quality of all linking variables, whereas this information is inherently generated by a probabilistic strategy. CONCLUSION PRL is more flexible and provides data about the quality of the linkage process that in turn can minimize the degree of linking errors, given the data provided.

An efficient validation method of probabilistic record linkage including readmissions and twins.

OBJECTIVE To describe an efficient, generalizable approach to validate probabilistic record linkage results, in particular by a model-guided detection of linking errors, and to apply this approach to validate linkage of admissions of newborns. METHODS Our double-blind validation procedure consisted of three steps: sample selection, data collection and data analysis. The linked Dutch national newborn admission registry contained 30,082 records for 2001 including readmissions (7.4%) and twins (9.7%). A highly informative sample was selected from the linked file by oversampling uncertain links based on model-derived linking weight. Four hundred and eight fax forms with minimal registry information (admissions of 191 children) were sent out to different pediatric units. The pediatricians were asked to create a short detailed patient history from independent sources. The linkage status and additional record data was validated against this external information. RESULTS Response rate was 97% (395/408 faxes). Accuracy of the linkage of singleton admissions was high: except for some expected errors in the uncertain area (0.02% of record pairs), linkage was error-free. Validation of multiple birth readmissions showed 37% linkage errors due to low data quality of the multiple birth variables. The quality of the linked registry file was still high; only 1.7% of the children were from a multiple birth with multiple admissions, resulting in less than 1% linking error. CONCLUSIONS Our external validation procedure of record linkage was feasible, efficient, and informative about identifying the source of the errors.

Is psychosocial stress in first ongoing pregnancies associated with pre-eclampsia and gestational hypertension?

Objective  Investigating the association of pre‐eclampsia and gestational hypertension with psychosocial stress in the first half of pregnancy.

Folic acid knowledge and use in a multi‐ethnic pregnancy cohort: the role of language proficiency

Objective  To investigate the role of language proficiency as determinant of folic acid knowledge and use in a multi‐ethnic pregnancy cohort.

Ethnic differences in TSH but not in free T4 concentrations or TPO antibodies during pregnancy

Objective  To describe the TSH, free T4 and thyroid peroxidase antibody (TPO‐Ab) concentrations during pregnancy among four ethnic groups and to determine reference values for these parameters during normal pregnancy.

Maternal pre-pregnancy body mass index explains infant’s weight and BMI at 14 months: results from a multi-ethnic birth cohort study

Objective: To investigate the association between (self-reported) maternal pre-pregnancy body mass index (pBMI), and child’s weight, height and BMI at age 14 months. Design: Prospective multi-ethnic community-based cohort study. Setting: Amsterdam, The Netherlands. Participants: 8266 pregnant women from the Amsterdam Born Children and their Development study, filled out a questionnaire covering socio-demographic data, obstetric history, lifestyle, dietary habits and psychosocial factors, 2 weeks after their first antenatal visit. 7730 gave birth to a viable term singleton infant with information on birth weight, gender and pregnancy duration. Growth data were available for 3171 of these children. Main outcome measures: Weight (g), height (cm) and BMI (kg/m2) of the child at age 14 months. Results: pBMI was linearly associated with weight and BMI of the child at age 14 months. One unit increase in pBMI resulted in an increment of 29 g (95% CI 19 to 39) in weight and 0.041 kg/m2 (95% CI 0.030 to 0.053) in BMI. The effect size decreased after adjustment for birth weight (weight: β coefficient 19 g, 95% CI 10 to 28; BMI: β coefficient 0.034 kg/m2, 95% CI 0.023 to 0.046) and hardly changed after adjustment for all other variables (weight: β coefficient 21 g, 95% CI 11 to 30; BMI: β coefficient 0.031 kg/m2, 95% CI 0.019 to 0.043). pBMI was not related to height. Conclusions: pBMI is an independent determinant of weight and BMI of the child at age 14 months. At least one third of this effect is mediated through birth weight.

Intensification of fetal and maternal surveillance in pregnant women with hypertensive disorders

Objective: To examine the need to intensify fetal and maternal surveillance in pregnant women with mild pregnancy hypertension. Methods: The multi‐center cohort study in 2413 healthy nulliparae analyzed differences in hypertension‐related adverse events (small‐for‐gestational age, perinatal mortality, eclampsia, abruptio placentae and HELLP syndrome) according to maximum diastolic blood pressure and proteinuria. Results: Compared to the reference group (diastolic blood pressure 70–85 mmHg) (n=1882) the relative risks of adverse fetal and maternal outcome in 34 proteinuric hypertensive women were 8.9 (95% CI 3.3–24.1) and 41.5 (95% CI 9.7–178.4), respectively. In 203 non‐proteinuric women with a maximum diastolic blood pressure of ≥95 mmHg only the relative risk of adverse maternal outcome was increased (11.6, 95% CI 3.1–42.8), but it was not increased in 230 non‐proteinuric women with a maximum diastolic of 90 mmHg. Conclusions: Intensified surveillance in women with mild pregnancy hypertension is not indicated and should be reserved for groups with increased fetal and maternal risk.

Deprived neighborhoods and adverse perinatal outcome: a systematic review and meta‐analysis

This study aims to summarize evidence on the relation between neighborhood deprivation and the risks for preterm birth, small‐for‐gestational age, and stillbirth.