Genetic and environmental factors driving congenital solitary functioning kidney.

BACKGROUND: Congenital solitary functioning kidney (CSFK) is an anomaly predisposing to hypertension, albuminuria and chronic kidney disease. Its aetiology is complex and includes genetic and environmental factors. The role of gene-environment interactions (G×E), although relevant for other congenital anomalies, has not yet been investigated. Therefore, we performed a genome-wide G×E analysis with six preselected environmental factors to explore the role of these interactions in the aetiology of CSFK. METHODS: In the AGORA (Aetiologic research into Genetic and Occupational/environmental Risk factors for Anomalies in children) data- and biobank, genome-wide single-nucleotide variant (SNV) data and questionnaire data on prenatal exposure to environmental risk factors were available for 381 CSFK patients and 598 healthy controls. Using a two-step strategy, we first selected independent significant SNVs associated with one of the six environmental risk factors. These SNVs were subsequently tested in G×E analyses using logistic regression models, with Bonferroni-corrected P-value thresholds based on the number of SNVs selected in step one. RESULTS: In step one, 7-40 SNVs were selected per environmental factor, of which only rs3098698 reached statistical significance (P = .0016, Bonferroni-corrected threshold 0.0045) for interaction in step two. The interaction between maternal overweight and this SNV, which results in lower expression of the Arylsulfatase B (ARSB) gene, could be explained by lower insulin receptor activity in children heterozygous for rs3098698. Eight other G×E interactions had a P-value <.05, of which two were biologically plausible and warrant further study. CONCLUSIONS: Interactions between genetic and environmental factors may contribute to the aetiology of CSFK. To better determine their role, large studies combining data on genetic and environmental risk factors are warranted.

The risk of miscarriage after COVID-19 vaccination before and during pregnancy.

PURPOSE: Pregnant women are at higher risk of severe illness and adverse pregnancy outcomes due to a SARS-CoV-2 infection, which can be prevented by vaccination. Observational studies are needed to ascertain the safety of COVID-19 vaccination during pregnancy. We aimed to determine whether COVID-19 vaccination before and during pregnancy is associated with the risk of miscarriage. METHODS: In this cohort study, we included 4640 pregnant women (mean age: 32.8 ± 3.7 years) from the Dutch Pregnancy Drug Register between February 2021 and August 2022. Information on COVID-19 vaccinations, miscarriage, and confounders was self-reported, using web-based questionnaires. The hazard ratio (HR) of miscarriage (in gestational weeks 6-20) after a COVID-19 vaccination, was estimated using the survival analyses. A COVID-19 vaccination during pregnancy (≥1 COVID-19 vaccination between week 2 and 20 of pregnancy) was included as a time-dependent exposure and vaccination prior to pregnancy was included as a binary exposure. RESULTS: A total of 3202 pregnant women (69%) received ≥1 COVID-19 vaccine in gestational week 2-20. We observed no association of vaccination during pregnancy with the risk of miscarriage (adjusted HR = 1.29, 95% CI = 0.93-1.74). Vaccination prior to pregnancy, however, was associated with a decreased risk of miscarriage (adjusted HR = 0.69, 95% CI = 0.48-0.99). CONCLUSIONS: We demonstrated that COVID-19 vaccination during pregnancy is not associated with an increased risk of miscarriage in gestational weeks 6-20. This study adds to the growing body of evidence demonstrating the safety of COVID-19 vaccination during pregnancy.

Adherence to prescription medication during pregnancy: Do pregnant women use pharmacological treatment as prescribed?

AIMS: Pregnant women are hypothesized to have low adherence to prescribed medication, because of concerns about harmful effects on the unborn child. However, very little is known about the actual adherence to prescribed medication during pregnancy. We determined to what extent women follow treatment recommendations regarding prescribed medication use in mid-pregnancy. METHODS: Dutch women participating in the PRIDE Study completed a 6-week diary on medication use. Additionally, pharmacy records were obtained. For each medication dispensed, we determined 3 measures of adherence: (i) whether use was reported in the diary (actual use); (ii) difference between dispensing date and date of first reported use (initiation time); and (iii) proportion of days with at least the correct number of doses taken (implementation adherence). RESULTS: During the 6-week study period, 235 of 816 women (29%) were dispensed medication. Actual use was highest for medications used for chronic conditions (88%; 95% confidence interval [95% CI] 81-93), followed by medication for pregnancy-related conditions (79%; 95% CI 71-86) and medication for occasional and short-time use (69%; 95% CI 60-77). We observed a ≥1-day delay in treatment initiation for 42% of medications dispensed for the first time in the study period. Mean implementation adherence was 74.2% (95% CI 69.3-79.2) for medications that were actually used. CONCLUSION: Although actual use of medications dispensed was high, many pregnant women did not adhere to treatment recommendations. This nonadherence may impact maternal and child health and lead to overestimation of medication use in studies in perinatal pharmacoepidemiology relying on administrative databases.

Longitudinal Methods for Modeling Exposures in Pharmacoepidemiologic Studies in Pregnancy.

In many perinatal pharmacoepidemiologic studies, exposure to a medication is classified as "ever exposed" versus "never exposed" within each trimester or even over the entire pregnancy. This approach is often far from real-world exposure patterns, may lead to exposure misclassification, and does not to incorporate important aspects such as dosage, timing of exposure, and treatment duration. Alternative exposure modeling methods can better summarize complex, individual-level medication use trajectories or time-varying exposures from information on medication dosage, gestational timing of use, and frequency of use. We provide an overview of commonly used methods for more refined definitions of real-world exposure to medication use during pregnancy, focusing on the major strengths and limitations of the techniques, including the potential for method-specific biases. Unsupervised clustering methods, including k-means clustering, group-based trajectory models, and hierarchical cluster analysis, are of interest because they enable visual examination of medication use trajectories over time in pregnancy and complex individual-level exposures, as well as providing insight into comedication and drug-switching patterns. Analytical techniques for time-varying exposure methods, such as extended Cox models and Robins' generalized methods, are useful tools when medication exposure is not static during pregnancy. We propose that where appropriate, combining unsupervised clustering techniques with causal modeling approaches may be a powerful approach to understanding medication safety in pregnancy, and this framework can also be applied in other areas of epidemiology.

Associations between maternal awakening salivary cortisol levels in mid-pregnancy and adverse birth outcomes.

PURPOSE: Elevated levels of maternal cortisol have been hypothesized as the intermediate process between symptoms of depression and psychosocial stress during pregnancy and adverse birth outcomes. Therefore, we examined associations between cortisol levels in the second trimester of pregnancy and risks of three common birth outcomes in a nested case-control study. METHODS: This study was embedded in the PRIDE Study (n = 3,019), from which we selected all cases with preterm birth (n = 64), low birth weight (n = 49), and small-for-gestational age (SGA; n = 65), and 260 randomly selected controls, among the participants who provided a single awakening saliva sample in approximately gestational week 19 in 2012-2016. Multivariable linear and logistic regression was performed to assess the associations between continuous and categorized cortisol levels and the selected outcomes. RESULTS: We did not observe any associations between maternal cortisol levels and preterm birth and low birth weight. However, high cortisol levels (≥ 90th percentile) seemed to be associated with SGA (adjusted odds ratio 2.1, 95% confidence interval 0.9-4.8), in particular among girls (adjusted odds ratio 3.7, 95% confidence interval 1.1-11.9, based on eight exposed cases) in an exploratory analysis. CONCLUSION: The results of this study showed no suggestions of associations between maternal awakening cortisol levels in mid-pregnancy and adverse birth outcomes, except for an increased risk of SGA.

Prior use of therapeutic anticoagulation does not protect against COVID-19 related clinical outcomes in hospitalized patients: A propensity score-matched cohort study.

The hypercoagulable state observed in COVID-19 could be responsible for morbidity and mortality. In this retrospective study we investigated whether therapeutic anticoagulation prior to infection has a beneficial effect in hospitalized COVID-19 patients. This study included 1154 COVID-19 patients admitted to 6 hospitals in the Netherlands between March and May 2020. We applied 1:3 propensity score matching to evaluate the association between prior therapeutic anticoagulation use and clinical outcome, with in hospital mortality as primary endpoint. In total, 190 (16%) patients used therapeutic anticoagulation prior to admission. In the propensity score matched analyses, we observed no associations between prior use of therapeutic anticoagulation and overall mortality (risk ratio 1.02 [95% confidence interval; 0.80-1.30]) or length of hospital stay (7.0 [4-12] vs. 7.0 [4-12] days, P = .69), although we observed a lower risk of pulmonary embolism (0.19 [0.05-0.80]). This study shows that prior use of therapeutic anticoagulation is not associated with improved clinical outcome in hospitalized COVID-19 patients.

Changes in parental smoking during pregnancy and risks of adverse birth outcomes and childhood overweight in Europe and North America: An individual participant data meta-analysis of 229,000 singleton births.

BACKGROUND: Fetal smoke exposure is a common and key avoidable risk factor for birth complications and seems to influence later risk of overweight. It is unclear whether this increased risk is also present if mothers smoke during the first trimester only or reduce the number of cigarettes during pregnancy, or when only fathers smoke. We aimed to assess the associations of parental smoking during pregnancy, specifically of quitting or reducing smoking and maternal and paternal smoking combined, with preterm birth, small size for gestational age, and childhood overweight. METHODS AND FINDINGS: We performed an individual participant data meta-analysis among 229,158 families from 28 pregnancy/birth cohorts from Europe and North America. All 28 cohorts had information on maternal smoking, and 16 also had information on paternal smoking. In total, 22 cohorts were population-based, with birth years ranging from 1991 to 2015. The mothers' median age was 30.0 years, and most mothers were medium or highly educated. We used multilevel binary logistic regression models adjusted for maternal and paternal sociodemographic and lifestyle-related characteristics. Compared with nonsmoking mothers, maternal first trimester smoking only was not associated with adverse birth outcomes but was associated with a higher risk of childhood overweight (odds ratio [OR] 1.17 [95% CI 1.02-1.35], P value = 0.030). Children from mothers who continued smoking during pregnancy had higher risks of preterm birth (OR 1.08 [95% CI 1.02-1.15], P value = 0.012), small size for gestational age (OR 2.15 [95% CI 2.07-2.23], P value < 0.001), and childhood overweight (OR 1.42 [95% CI 1.35-1.48], P value < 0.001). Mothers who reduced the number of cigarettes between the first and third trimester, without quitting, still had a higher risk of small size for gestational age. However, the corresponding risk estimates were smaller than for women who continued the same amount of cigarettes throughout pregnancy (OR 1.89 [95% CI 1.52-2.34] instead of OR 2.20 [95% CI 2.02-2.42] when reducing from 5-9 to ≤4 cigarettes/day; OR 2.79 [95% CI 2.39-3.25] and OR 1.93 [95% CI 1.46-2.57] instead of OR 2.95 [95% CI 2.75-3.15] when reducing from ≥10 to 5-9 and ≤4 cigarettes/day, respectively [P values < 0.001]). Reducing the number of cigarettes during pregnancy did not affect the risks of preterm birth and childhood overweight. Among nonsmoking mothers, paternal smoking was associated with childhood overweight (OR 1.21 [95% CI 1.16-1.27], P value < 0.001) but not with adverse birth outcomes. Limitations of this study include the self-report of parental smoking information and the possibility of residual confounding. As this study only included participants from Europe and North America, results need to be carefully interpreted regarding other populations. CONCLUSIONS: We observed that as compared to nonsmoking during pregnancy, quitting smoking in the first trimester is associated with the same risk of preterm birth and small size for gestational age, but with a higher risk of childhood overweight. Reducing the number of cigarettes, without quitting, has limited beneficial effects. Paternal smoking seems to be associated, independently of maternal smoking, with the risk of childhood overweight. Population strategies should focus on parental smoking prevention before or at the start, rather than during, pregnancy.

Maternal hypertensive disorders and subtypes of hypospadias: A Dutch case-control study.

BACKGROUND: Hypospadias is a frequently occurring congenital anomaly in male infants, in which the opening of the urethra is located along the ventral side of the penis. Although various studies attempted to identify its causes, the aetiology of the majority of hypospadias cases remains poorly understood. Maternal hypertensive disorders are believed to be associated with hypospadias, but the results of previous studies are not consistent, especially for subtypes of hypospadias. OBJECTIVES: To investigate the associations between maternal hypertensive disorders, stratified by pharmacological treatment, and the occurrence of hypospadias divided into subtypes in a large population-based case-control study. METHODS: We included 887 hypospadias cases and 1005 male controls from the AGORA data- and biobank. Cases and controls were born in the periods 1975-2016 and 1990-2011, respectively. All data were collected in the period 2004-2018. Maternal questionnaires were used to obtain information on hypertensive disorders during pregnancy, antihypertensive medication treatment, and potential confounders. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for the associations between hypertensive disorders and hypospadias were estimated using logistic regression. RESULTS: Hypertensive disorders were reported by 15.3% of the women in this study. Maternal hypertensive disorders in general, chronic hypertension, and gestational hypertension were not associated with hypospadias or its subtypes. Preeclampsia was associated with posterior hypospadias (aOR 3.09, 95% CI 1.49, 6.43), whether it was untreated (aOR 2.81, 95% CI 1.24, 6.38) or pharmacologically treated preeclampsia (aOR 4.96, 95% CI 1.08, 22.80). CONCLUSIONS: Our findings indicate that preeclampsia is associated with posterior hypospadias, irrespective of pharmacological treatment. This result supports the hypothesis of aetiological heterogeneity among the subtypes of hypospadias, with pregnancy-related risk factors being associated with the more severe types of hypospadias.

The PRIDE Study: Evaluation of online methods of data collection.

BACKGROUND: Large birth cohort studies are extremely valuable in assessing associations between early life exposures and long-term outcomes. Establishing new birth cohorts is challenging due to declining participation rates. Online methods of data collection may increase feasibility, but have not been evaluated thoroughly. OBJECTIVE: The primary objective of the ongoing PRegnancy and Infant DEvelopment (PRIDE) Study is to identify exposures during pregnancy and in early life that may affect short-term or long-term health of mother and/or child. In this manuscript, we aimed to evaluate methods of recruitment and online data collection applied. POPULATION: Dutch women aged ≥18 years in early pregnancy. DESIGN: Prospective cohort study. METHODS: Initially, only prenatal care providers recruited participants, but alternative recruitment methods were added as a result of disappointing participation rates, including collaboration with "Moeders voor Moeders" (organisation that visits women in early pregnancy) and Facebook advertisements. Data on demographic characteristics, obstetric history, maternal health, life style factors, occupational exposures, nutrition, pregnancy complications, and infant outcomes are primarily collected through Web-based questionnaires at multiple time points during and after pregnancy. Additional data collection components include paternal questionnaires, blood and saliva sampling, and linkage to medical records. PRELIMINARY RESULTS: By September 2019, 9573 women were included in the PRIDE Study, of which 1.3% completed paper-based questionnaires. Mean age of the women analysed was 30.6 years, 71.1% had a high level of education, 57.2% were primiparae, and mean gestational age at enrolment was 9.9 (range 3, 37) weeks, with slight differences between recruitment methods. Pregnancy outcome was known for 89.8%. Retention rate at 6 months after the estimated date of delivery was estimated at 70%. Multiple validation studies conducted within the PRIDE Study indicated high data quality. CONCLUSION(S): Although challenging and time-consuming, online methods for recruitment and data collection may enable the establishment of new birth cohort studies.

External validation and clinical utility of prognostic prediction models for gestational diabetes mellitus: A prospective cohort study.

INTRODUCTION: We performed an independent validation study of all published first trimester prediction models, containing non-invasive predictors, for the risk of gestational diabetes mellitus. Furthermore, the clinical potential of the best performing models was evaluated. MATERIAL AND METHODS: Systemically selected prediction models from the literature were validated in a Dutch prospective cohort using data from Expect Study I and PRIDE Study. The predictive performance of the models was evaluated by discrimination and calibration. Clinical utility was assessed using decision curve analysis. Screening performance measures were calculated at different risk thresholds for the best model and compared with current selective screening strategies. RESULTS: The validation cohort included 5260 women. Gestational diabetes mellitus was diagnosed in 127 women (2.4%). The discriminative performance of the 12 included models ranged from 68% to 75%. Nearly all models overestimated the risk. After recalibration, agreement between the observed outcomes and predicted probabilities improved for most models. CONCLUSIONS: The best performing prediction models showed acceptable performance measures and may enable more personalized medicine-based antenatal care for women at risk of developing gestational diabetes mellitus compared with current applied strategies.

Social media monitoring on the perceived safety of medication use during pregnancy: A case study from the Netherlands.

AIMS: An increasing number of women trust the Internet for information about medication safety during pregnancy. This study aimed to evaluate the availability and accuracy of social media content on the perceived safety of medication use in pregnancy. METHODS: We performed a systematic search of posts related to medication safety during pregnancy in the Dutch language published on social media, blogs and forums between May 2011 and April 2016 using Coosto, a tool for social media monitoring. The perceived safety in the posts was compared with the Dutch Teratology Information Service (TIS) safety classifications. RESULTS: We included 1224 online posts, which described 1441 scenarios about medication safety in pregnancy. A total of 820 (57%) scenarios were in line with the TIS classification. Incorrect perception was higher for prescription medication compared to medication available over-the-counter (60 vs 25%). Furthermore, the safety classification of medications with a TIS classification on strict indication or second-line drugs (93%) and medications with insufficient knowledge on their safety during pregnancy (76%) was more likely to be incorrectly perceived by the public compared to medications with the TIS classification safe (24%). CONCLUSIONS: Social media monitoring may be useful for surveillance of potentially unsafe use of medications in pregnancy. Many social posts related to medication safety during pregnancy provide inaccurate information. As this information may affect women's perceptions and decisions, accurate communication between healthcare providers and pregnant women regarding the benefits and risks of medications is vital.

Google AdWords and Facebook Ads for Recruitment of Pregnant Women into a Prospective Cohort Study With Long-Term Follow-Up.

Objectives Several types of epidemiologic studies suffer from decreasing participation rates, resulting in potential selection bias and delay or termination of studies. We aimed to determine the feasibility of online methods for recruitment of pregnant women into a prospective cohort study. Methods In addition to traditional recruitment through prenatal care providers, we advertized participation in the PRegnancy and Infant DEvelopment (PRIDE) Study, an ongoing prospective cohort study with long-term follow-up in The Netherlands enrolling women in early pregnancy, through Google AdWords (30 days) and Facebook Ads (31 and 27 days) campaigns between September 2016 and January 2017. We calculated costs per eligible participant and compared demographics, health-related characteristics, and follow-up rates between participants recruited through online methods and prenatal care providers. Results During the study period, we recruited six women through AdWords (€54.28 per participant), 59 through Facebook (€10.17 per participant), and 327 through prenatal care providers (no valid cost estimate available). Facebook participants seemed to be younger (29.0 vs. 30.7 years), to have a higher body mass-index and/or low/intermediate education (27.0 vs. 24.0 kg/m2 and 41 vs. 25%, respectively), and to start prenatal care in secondary care more often (12 vs. 5%) than participants recruited through prenatal care providers. Item non-response and loss to follow-up rates were higher among women recruited online than among those recruited through prenatal care providers. Conclusion Google AdWords did not contribute substantially, but Facebook Ads may complement traditional recruitment methods of pregnant women into prospective cohort studies, despite challenges that may threaten internal validity.

Using Web-Based Questionnaires to Assess Medication Use During Pregnancy: A Validation Study in 2 Prospectively Enrolled Cohorts.

Medication use is often underreported in paper-based questionnaires or interviews. Web-based questionnaires may improve recall of medication use, but data on their validity are currently lacking. Participants in the Pregnancy and Infant Development (PRIDE) Study (2014-2016; n = 557) and the Pregnancy Drug Registry (pREGnant) (2015-2016; n = 169) completed a 6-week paper-based medication diary during gestational weeks 19-24 or 26-31. In week 34, they completed a Web-based questionnaire with questions on medication names, time period and frequency of use, and quantity taken. To assess the degree of underreporting, we calculated the questionnaire's sensitivity using the medication diary as the reference standard. Sensitivity was high for many medication groups, including antiepileptic medication (sensitivity (Sn) = 0.96, 95% confidence interval (CI): 0.89, 1.00), antacids (Sn = 0.89, 95% CI: 0.86, 0.93), and iron preparations (Sn = 0.81, 95% CI: 0.64, 0.98). However, medications for short-term use were underreported more frequently, with sensitivities of 0.54 (95% CI: 0.35, 0.72) for antihistamines, 0.63 (95% CI: 0.57, 0.69) for analgesic and antipyretic agents, and 0.57 (95% CI: 0.51, 0.64) for acetaminophen. Shortening the period of time between exposure and questionnaire administration increased sensitivity substantially. In conclusion, underreporting in Web-based questionnaires is limited for many medication groups. In prospective studies, underreporting of medications for short-term use may be reduced by decreasing the interval between consecutive questionnaires.

Making fair comparisons in pregnancy medication safety studies: An overview of advanced methods for confounding control.

Understanding the safety of medication use during pregnancy relies on observational studies: However, confounding in observational studies poses a threat to the validity of estimates obtained from observational data. Newer methods, such as marginal structural models and propensity calibration, have emerged to deal with complex confounding problems, but these methods have seen limited uptake in the pregnancy medication literature. In this article, we provide an overview of newer advanced methods for confounding control and show how these methods are relevant for pregnancy medication safety studies.

Depression and anxiety during pregnancy: The influence of maternal characteristics.

BACKGROUND: Depression and anxiety during pregnancy are associated with adverse health outcomes for both mother and child. This study aims to investigate the occurrence of symptoms of depression and anxiety in early and late pregnancy, the longitudinal changes from early to late pregnancy, and factors associated with symptoms of depression and anxiety in pregnant women in the Netherlands. METHODS: We studied 2897 women participating in the PRegnancy and Infant DEvelopment (PRIDE) Study. To assess symptoms of depression and anxiety, web-based questionnaires including the Hospital Anxiety and Depression Scale (HADS) and multiple questions on maternal characteristics were completed in early and late pregnancy. Cross-sectional and longitudinal multivariable linear regression analyses were conducted. RESULTS: The depressive symptoms in our population increased, with a prevalence of probable depression from 5.4% in early pregnancy to 10.0% in late pregnancy (P < .001), whereas the anxiety symptoms decreased, with a prevalence of probable anxiety from 17.9% to 14.2% (P < .001). Characteristics associated with depressive or anxiety symptoms included low level of education, multiparity, a history of depression, severe nausea, extreme fatigue, lack of physical exercise, and negative life events. Being non-Dutch, not living with a partner, and having an unplanned pregnancy or a long time to pregnancy were associated with the depressive and/or anxiety symptoms in early pregnancy only. DISCUSSION: Symptoms of depression and anxiety are common in both early and late pregnancy. Screening for risk factors in early pregnancy is important, since prenatal depression and anxiety may be related to adverse maternal and child health outcomes.

Prenatal maternal psychological stress and childhood asthma and wheezing: a meta-analysis.

The aim of this study was to systematically review and meta-analyse observational studies on prenatal maternal psychological stress and the subsequent development of asthma and wheezing in early childhood.All available published literature from 1960 until November 2013 was systematically searched through electronic databases (PubMed, Embase, PsycInfo and Web of Science). All observational studies assessing associations between any form of prenatal maternal psychological stress and respiratory morbidity in the child were included. Data extraction, quality assessment and meta-analyses were performed.The overall meta-analysis included 10 studies and showed that the prevalence of wheezing, asthma and other respiratory symptoms is higher in children of mothers who were exposed to or experienced some form of psychological stress during pregnancy than in mothers who did not (pooled OR 1.56 (95% CI 1.36-1.80)). Comparable results were observed in subgroup analyses of stress exposure, perceived stress, asthma and wheezing.This study demonstrates that prenatal maternal psychological stress is associated with respiratory morbidity, including asthma and wheezing in the child. Future studies examining the early origins of asthma and wheezing need to account for the impact of prenatal maternal stress.

Using Web-Based Questionnaires and Obstetric Records to Assess General Health Characteristics Among Pregnant Women: A Validation Study.

BACKGROUND: Self-reported medical history information is included in many studies. However, data on the validity of Web-based questionnaires assessing medical history are scarce. If proven to be valid, Web-based questionnaires may provide researchers with an efficient means to collect data on this parameter in large populations. OBJECTIVE: The aim of this study was to assess the validity of a Web-based questionnaire on chronic medical conditions, allergies, and blood pressure readings against obstetric records and data from general practitioners. METHODS: Self-reported questionnaire data were compared with obstetric records for 519 pregnant women participating in the Dutch PRegnancy and Infant DEvelopment (PRIDE) Study from July 2011 through November 2012. These women completed Web-based questionnaires around their first prenatal care visit and in gestational weeks 17 and 34. We calculated kappa statistics (κ) and the observed proportions of positive and negative agreement between the baseline questionnaire and obstetric records for chronic conditions and allergies. In case of inconsistencies between these 2 data sources, medical records from the woman's general practitioner were consulted as the reference standard. For systolic and diastolic blood pressure, intraclass correlation coefficients (ICCs) were calculated for multiple data points. RESULTS: Agreement between the baseline questionnaire and the obstetric record was substantial (κ=.61) for any chronic condition and moderate for any allergy (κ=.51). For specific conditions, we found high observed proportions of negative agreement (range 0.88-1.00) and on average moderate observed proportions of positive agreement with a wide range (range 0.19-0.90). Using the reference standard, the sensitivity of the Web-based questionnaire for chronic conditions and allergies was comparable to or even better than the sensitivity of the obstetric records, in particular for migraine (0.90 vs 0.40, P=.02), asthma (0.86 vs 0.61, P=.04), inhalation allergies (0.92 vs 0.74, P=.003), hay fever (0.90 vs 0.64, P=.001), and allergies to animals (0.89 vs 0.53, P=.01). However, some overreporting of allergies was observed in the questionnaire and for some nonsomatic conditions sensitivity of both measurement instruments was low. The ICCs for blood pressure readings ranged between 0.72 and 0.92 with very small mean differences between the 2 methods of data collection. CONCLUSIONS: Web-based questionnaires can be used to validly collect data on many chronic disorders, allergies, and blood pressure readings among pregnant women.

Drugs associated with teratogenic mechanisms. Part II: a literature review of the evidence on human risks.

STUDY QUESTION: What is the current state of knowledge on the human risks of drugs suspected to be associated with teratogenic mechanisms? SUMMARY ANSWER: Evidence for the presence or absence of human risks of birth defects is scarce or non-existent for the majority of drugs associated with teratogenic mechanisms. WHAT IS KNOWN ALREADY: Medical drugs suspected to be associated with teratogenic mechanisms are dispensed to a significant proportion of women in the first trimester of pregnancy. However, an overview of the current state of knowledge on the human teratogenic effects of these drugs is lacking. STUDY DESIGN, SIZE, DURATION: We performed an extensive literature review of studies in the English language which examined the associations between selected drugs and specific birth defects. The literature was identified from MEDLINE and EMBASE from database inception (January 1946 and January 1974, respectively) through December 2012 using 287 terms for the drugs of interest. We only included studies if they specified birth defect subtypes and, specifically for cohort studies, involved live born infants. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of 14 406 potentially relevant articles, 556 full-text articles were assessed for eligibility and 250 met the inclusion criteria. The studies included were divided into four categories according to their design to increase the validity of our study. MAIN RESULTS AND THE ROLE OF CHANCE: Epidemiologic studies assessing teratogenic risks were identified for less than half of the drugs included in the review. A substantial variation in study design and data collection methods was observed. When the data collection method is of questionable validity, study quality may be affected considerably. For only 15 drugs of interest, birth defects were assessed in at least 1000 infants in cohort studies, and 13 of these were associated with one or more specific birth defects. The majority of associations observed in case-control studies are as yet unconfirmed. For most drugs and drug groups, however, the numbers of exposed infants studied were too small to draw any conclusions regarding their human teratogenic risks. LIMITATIONS, REASONS FOR CAUTION: The validity of our review is limited by the validity and reporting of the studies from which the data were extracted. Some relevant studies might have been missed owing to the exclusion of articles not in the English language and publication bias. WIDER IMPLICATIONS OF THE FINDINGS: It is a cause of concern that the drugs most often dispensed in the first trimester of pregnancy are not necessarily the drugs for which teratogenic risks have been studied. Future studies should focus on those drugs that are most commonly used during pregnancy and for which the teratogenic risks are unknown, such as iron preparations, serotonin receptor agonists or antagonists, drugs used in fertility treatment, dihydrofolate reductase inhibitors. STUDY FUNDING/COMPETING INTEREST(S): Marleen van Gelder was supported by the Netherlands Organisation for Scientific Research/NWO (grant no. 021.001.008). No competing interests are declared. TRIAL REGISTRATION NUMBER: N/A.

Drugs associated with teratogenic mechanisms. Part I: dispensing rates among pregnant women in the Netherlands, 1998-2009.

STUDY QUESTION: What are the dispensing rates of drugs suspected to be associated with teratogenic mechanisms among pregnant Dutch women? SUMMARY ANSWER: In a substantial proportion of pregnancies in our study population at least one drug associated with a teratogenic mechanism was dispensed in the first trimester of pregnancy. WHAT IS KNOWN ALREADY: The main teratogenic mechanisms of medical drugs that may affect fetal development in the first trimester of pregnancy have been described previously. However, information on the dispensing rate of such drugs among women at all stages of pregnancy is lacking. STUDY DESIGN, SIZE, DURATION: To determine how often medications suspected to be associated with a teratogenic mechanism are used by pregnant women, we studied 32 016 pregnancies included in the IADB.nl database between 1998 and 2009. PARTICIPANTS/MATERIALS, SETTING, METHODS: We estimated dispensing rates of medical drugs suspected to be associated with teratogenic mechanisms in our study population. The IADB.nl database includes all pharmacy dispensings for an estimated population of 220 000 in 1994-1998 and c.500 000 since 1999. In addition, trends in first trimester dispensing rates over time and patterns of receiving multiple drugs associated with teratogenic mechanisms were evaluated. In addition, we determined the number of pregnancies in which multiple prescription drugs from one or more teratogenic categories were dispensed in the first trimester, and we evaluated the numbers of different medications dispensed that could be grouped within a specific teratogenic mechanism. MAIN RESULTS AND THE ROLE OF CHANCE: In 175 per 1000 pregnancies [95% confidence interval (CI), 171-179] at least one drug associated with a teratogenic mechanism was dispensed in the first trimester. The total dispensing rate was 236 per 1000 pregnancies (95% CI 232-241) in the 3 months before pregnancy and an increasing trend was seen in the second [214 per 1000 (95% CI 209-218)] and third [327 per 1000 (95% CI 322-332)] trimesters. The first trimester dispensing rates increased between 1998 and 2009 for selective serotonin-reuptake inhibitors (P < 0.001) and serotonin receptor agonists/antagonists (P < 0.001). In 71.8% of pregnancies in which drugs associated with teratogenic mechanisms were dispensed in the first trimester, women received drugs related to only one mechanism. Of the pregnancies in which drugs from multiple teratogenic categories were dispensed in the first trimester, 1148 (72.6%) women received drugs from 2 categories, 317 (20.0%) from three categories, 88 (5.6%) from 4 categories, 28 (1.8%) from 5 categories and 1 from 6 categories. Several women received multiple prescription medications grouped within a single teratogenic mechanism in the first trimester, ranging between 13.3% for cyclo-oxygenase inhibitors and 41.8% for serotonin receptor agonists/antagonists. LIMITATIONS, REASONS FOR CAUTION: We used a dispensing database, therefore actual use of the medication prescribed is unknown and non-compliance could have led to overestimation of exposure prevalences. WIDER IMPLICATIONS OF THE FINDINGS: Owing to the uncertainties concerning the safety of medication use during pregnancy, the results of this study stress the need for cautious prescription of medication associated with teratogenic mechanisms to women of reproductive age. This is further supported by our finding that women received multiple prescription medications grouped within a single teratogenic mechanism in the first trimester, which would theoretically increase strongly the risk of birth defects. STUDY FUNDING/COMPETING INTEREST(S): Marleen van Gelder was supported by the Netherlands Organisation for Scientific Research/NWO (grant no. 021.001.008). No competing interests are declared. TRIAL REGISTRATION NUMBER: N/A.