Methodological issues in the epidemiological study of the teratogenicity of drugs

Protocol of a prospective and multicentre China Teratology Birth Cohort (CTBC): association of maternal drug exposure during pregnancy with adverse pregnancy outcomes

BACKGROUND

As reported, 27-93 % of pregnant women take at least one drug during pregnancy. However, drug exposure during pregnancy still lacks sufficient foetal safety evidence of human origin. It is urgent to fill the knowledge gap about medication safety during pregnancy for optimization of maternal disease treatment and pregnancy drug consultation.

METHODS AND ANALYSIS

The China Teratology Birth Cohort (CTBC) was established in 2019 and is a hospital-based open-ended prospective cohort study with the aim of assessing drug safety during pregnancy. Pregnant women who set up the pregnancy health records in the first trimester or who seek drug consultation regardless of gestational age in the member hospitals are recruited. Enrolled pregnant women need to be investigated four times, namely, 6-14 and 24-28 weeks of gestational age, before discharge after hospital delivery, and 28-42 days after birth. Maternal medication exposure during pregnancy is the focus of the CTBC. For drugs, information on the type, name, and route of medication; start and end time of medication; single dose; frequency of medication; dosage form; manufacturer; and reason for medication is collected. The adverse pregnancy outcomes collected in the study include birth defects, stillbirth, spontaneous abortion, preterm birth, post-term birth, low birth weight, macrosomia, small for gestational age, large for gestational age and low Apgar score. CTBC uses an electronic questionnaire for data collection and a cloud system for data management. Biological samples are collected if informed consents are obtained. Multi-level logistic regression, mixed-effect negative binomial distribution regression and spline function regression are used to explore the effect of drugs on the occurrence of birth defects.

DISCUSSION

The findings of the study will assist in further understanding the risk of birth defects and other adverse pregnancy outcomes associated with maternal drug exposure and developing the optimal treatment plans and drug counselling for pregnant women.

TRIAL REGISTRATION

This study was approved by the Research Ethics Committee of the West China Second Hospital of Sichuan University and registered at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/index.aspx , registration number ChiCTR1900022569 ).

The incidence, risk factors and maternal and foetal outcomes of uterine rupture during different birth policy periods: an observational study in China

Background

Currently, there are no studies on changes in the incidence of uterine rupture or maternal and foetal outcomes in women with uterine rupture during different birth policy periods in China. Moreover, the results of association studies of maternal age, parity and previous caesarean section number with the risk of maternal and foetal outcomes in women with uterine rupture have not been consistent. This research aims to conduct and discuss the above two aspects.

Methods

We included singleton pregnant women with no maternal complications other than uterine rupture from January 2012 to June 2019 in China’s National Maternal Near Miss Surveillance System. The data in this study did not differentiate between complete and partial uterine rupture and uterine dehiscence. Through Poisson regression analysis with a robust variance estimator, we compared the incidences of uterine rupture and maternal and foetal outcomes in women with uterine rupture during different birth policy periods in China and determined the relationship between maternal age, parity or previous caesarean section number and uterine rupture or maternal and foetal outcomes in women with uterine rupture.

Results

This study included 8,637,723 pregnant women. The total incidences of uterine rupture were 0.13% (12,934) overall, 0.05% during the one-child policy, 0.12% during the partial two-child policy (aRR = 1.96; 95% CI: 1.53–2.52) and 0.22% (aRR = 2.89; 95% CI: 1.94 4.29) during the universal two-child policy. The maternal near miss and stillbirth rates in women with uterine rupture were respectively 2.35% (aRR = 17.90; 95% CI: 11.81–27.13) and 2.12% (aRR = 4.10; 95% CI: 3.19 5.26) overall, 5.46 and 8.18% during the first policy, 1.72% (aRR = 0.60; 95% CI: 0.32–1.17) and 2.02% (aRR = 0.57; 95% CI: 0.37–0.83) during the second policy, and 1.99% (aRR = 0.90; 95% CI: 0.52–1.53) and 1.04% (aRR = 0.36; 95% CI: 0.24–0.54) during the third policy. The risk of uterine rupture increased with parity and previous caesarean section number.

Conclusion

The uterine rupture rate in China continues to increase among different birth policy periods, and the risk of maternal near miss among women with uterine rupture has not significantly improved. The Chinese government, obstetricians, and scholars should work together to reverse the rising rate of uterine rupture and improve the pregnancy outcomes in women with uterine rupture.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03811-8.

In utero exposure to antibiotics and risk of congenital malformations: a population-based study

BACKGROUND

Antibiotics are commonly prescribed during pregnancy. Although the safety of most penicillins is well established, some controversy and uncertainty are associated with the use of other commonly prescribed antibiotics.

OBJECTIVE

To determine the risk of congenital malformations following first-trimester in utero exposure to 10 commonly prescribed antibiotics in Denmark.

MATERIALS AND METHODS

This was a cohort study comprising all singleton liveborn children in Denmark between 2000 and 2015. Data on malformations were collected through 2016. Merging validated and comprehensive populationwide Danish healthcare and civic registries, we merged data on pregnancy, prescription drugs purchases during first trimester and congenital malformations. Using logistic regression, we calculated the odds ratio for congenital malformations (any), major congenital malformations, and cardiac congenital malformations for the 10 most commonly prescribed antibiotics (excluding 4 penicillins that served as control). In the primary analysis, the exposed cohort was compared to a cohort exposed to any of 4 penicillins considered safe during pregnancy (ampicillin, pivampicillin, benzylpenicillin, and phenoxymethylpenicillin). In sensitivity analysis, the exposed cohort was compared to an unexposed cohort. Covariate adjustments were made for maternal age at delivery, year of delivery, parity, pre-pregnancy body mass index, smoking, educational status, employment status, and annual personal income.

RESULTS

We found no increased risk of congenital malformations to be related to first-trimester in utero exposure to the 10 most commonly prescribed antibiotics in Denmark compared to a cohort of pregnant women exposed to penicillins that are considered safe during pregnancy. Compared to unexposed pregnancies, small increased risks for major malformations and cardiac malformations were apparent for pivmecillinam (odds ratio, 1.13; confidence interval, 1.06-1.19; and odds ratio, 1.15; confidence interval, 1.04-1.28, respectively), sulfamethizole (odds ratio, 1.15; confidence interval, 1.07-1.24; and odds ratio, 1.22; confidence interval, 1.07-1.39, respectively), and azithromycin (odds ratio, 1.19, confidence interval, 1.03-1.38; and odds ratio, 1.29, confidence interval, 0.99-1.67, respectively).

CONCLUSION

In this large populationwide cohort study, we found, with a high degree of precision, no increased risk of congenital malformations following first-trimester exposure to 10 commonly prescribed systemic antibiotics.

The Safety of Second-Generation Antipsychotics During Pregnancy: A Clinically Focused Review

The issue of antipsychotic treatment during pregnancy is subject to substantial uncertainty and some controversy among healthcare providers, specifically pertaining to second-generation antipsychotics (SGAs) that are subject to a large gap in safety data during pregnancy compared with antidepressants. The amount of safety data for the use of SGAs during pregnancy is rapidly increasing, thus constantly changing the level of evidence. We performed a clinically focused review on the safety of SGA during pregnancy. Twenty-three studies provided various pregnancy outcomes for 14,382 pregnant women exposed to an SGA during pregnancy. In utero exposure to aripiprazole, olanzapine, and quetiapine is not associated with increased risks of major congenital malformations, whereas risperidone and paliperidone may be associated with a very minor increased risk of congenital malformations. Safety data on ziprasidone and clozapine remain scarce and insufficient for a quantitative safety evaluation. No or minimal safety data are available for amisulpride, asenapine, lurasidone, and sertindole. For other pregnancy outcomes of interest, e.g. miscarriage, stillbirth, and small for gestational age, the available data overall do not suggest a clinically important increased risk, and do not allow for a meaningful stratification on individual drug level. Furthermore, for neonatal adaption and childhood neurodevelopment, the data do not allow for a meaningful risk assessment. It is imperative that factors in addition to safety data, e.g. individual disease history, characteristics and treatment response, adverse reaction profile, and patient preferences, be considered for the individual patient when choosing specific SGA treatment during pregnancy.

Drug Use before and during Pregnancy in Japan: The Japan Environment and Children's Study

Purpose: To elucidate drug use before and during pregnancy in Japan. Methods: The Japan Environment and Children's Study (JECS) is an ongoing nationwide birth cohort study. We analyzed data from JECS involving cases where drugs were used for 12 months before pregnancy was diagnosed, between the time of diagnosis of pregnancy until week 12 of pregnancy, and after week 12 of pregnancy. Results: We analyzed data from 97,464 pregnant women. The percentages of pregnant women who had taken one or more drugs and supplements before diagnosis of pregnancy, between the time of diagnosis of pregnancy until week 12 of pregnancy, and after week 12 of pregnancy, were 78.4%, 57.1%, and 68.8% respectively. Excluding iron supplements, folic acid, and other vitamins and minerals, the percentages of women taking supplements were 75.3%, 36.0%, and 51.7% at each respective time point. The following drugs and supplements were frequently used for 12 months before pregnancy diagnosis: Commercially available antipyretics, analgesics, and/or medicine for treating common cold (34.7%), antipyretics, analgesics, and/or medicine for treating common colds, which were prescribed in hospitals (29.8%), antimicrobial drugs (14.0%), and anti-allergy drugs (12.5%). The following drugs and supplements were frequently used from the time of pregnancy diagnosis until week 12 of pregnancy, and after week 12 of pregnancy: folic acid (28.9% and 26.2%), antipyretics, analgesics and/or medicines for treating common cold, that were prescribed in hospitals (7.8% and 13.3%), Chinese herbal medicines (6.0% and 9.4%, and uterine relaxants (5.1% and 15.2%). Conclusions: The analysis of a nationwide cohort study showed that a high percentage of Japanese pregnant women were taking medicinal drugs. Further research is required to elucidate the relationship between drug use during pregnancy and birth defects in Japan.

Publishing negative findings and the challenge of avoiding type II errors in studies of suspect teratogens: Example of a recent ondansetron publication

It is important that negative, as well as positive, studies be published to complete the available picture in areas of scientific inquiry. At the same time, it is critical that the implications of a negative study not be overstated and generalized when major issues of study design and data accuracy may be the reason that no relationship was discovered. The challenge of avoiding type II errors in interpreting negative findings has major public health implications, especially when the relationship of an exposure to birth defects is the concern. This is particularly important when interpreting the report by Fazio et al. (June issue of Reproductive Toxicology) on the relationship of ondansetron exposure to pregnancy outcome and birth defects. This review addresses the study design and conclusions and suggests that an alternative concluding statement would be more apropos, given the limitations of the data.

Methodological challenges in using routinely collected health data to investigate long-term effects of medication use during pregnancy

To date, the investigation of teratogenic effects of medications has largely focused on physical alterations present at birth (i.e. malformations) as opposed to functional alterations (i.e. neurodevelopment, metabolic function) that may not be apparent at birth but could influence an individual's health and risk of disease in later life. The use of routinely collected health data represents one approach to better identifying, quantifying, and understanding the long-term risks or benefits of medication use during pregnancy. As such, the objective of this review was to identify and explore opportunities and challenges associated with using routinely collected health data to examine long-term effects of medication use during pregnancy. Drawing on published research several key methodological issues associated with their use in investigating long-term outcomes are reviewed. While significant opportunities exist to make greater use of routinely collected health data, there are a number of key challenges. Identified challenges relate to aspects of study design and analysis, and include obtaining access to data, the ability to match records across datasets and over long periods of time, how medication exposures are ascertained and classified, issues around loss to follow-up how outcomes are ascertained and classified, and the careful interpretation of results in light of study and data limitations. Understanding key challenges associated with using routinely collected health data to investigate long-term effects of medication use during pregnancy is essential in supporting their appropriate use and interpretation, which will contribute to improving the quality of research undertaken and ensure the reliability of results obtained.

Probabilistic record linkage for monitoring the safety of artemisinin-based combination therapy in the first trimester of pregnancy in Senegal

BACKGROUND

There are insufficient data on the safety in early pregnancy of the artemisinins, a new class of antimalarials. Assessment of drug teratogenicity requires large sample sizes for an adequate risk-benefit assessment. There is currently limited pharmacovigilance infrastructure in malaria-endemic countries. Monitoring drug safety in early pregnancy is especially challenging, as it requires early pregnancy detection to assess any potential increased risk of miscarriage, prospective follow-up to reduce recall and survival biases, and accurate data on gestational age assessment. Record linkage approaches for pregnancy pharmacovigilance using routinely generated health records could be a pragmatic and cost-effective approach for pharmacovigilance in early pregnancy, but has not been evaluated in resource-poor settings.

OBJECTIVE

Our objective was to assess the feasibility of record linkage using routinely collected healthcare data as a pragmatic means of monitoring the safety in early pregnancy of artemisinin-based combination therapies (ACTs) in Senegal.

METHODS

Data (2004-2008) from paper-based registers from outpatient clinics, antenatal care services (ANC) and the delivery unit from the St Joseph dispensary in Mlomp, south-western Senegal, were entered into databases. Record linkage based on a probabilistic matching approach was used to identify pregnancies exposed to ACTs in the first trimester of pregnancy. Two record linkage software packages (Link-Plus and FRIL) were compared and output data were reviewed independently by two investigators.

RESULTS

Information on 685 pregnancies was extracted, 536 of which were from the geographic catchment area and eligible for record linkage; 94.6 % of them resulted in live births, 2.6 % in stillbirths and 2.8 % in miscarriages. Major congenital malformations were identified in 1.6 % of births. Seventy-three and 75 true matches between pregnancy outcome and the outpatient treatment registers were identified by two different record linkage software packages, respectively. Record linkage identified seven exposures to ACTs in the first trimester, all of which resulted in normal live-births.

CONCLUSION

Probabilistic record linkage is a potentially cost-effective method to assess the safety of antimalarials in early pregnancy in resource-constrained settings to assess increased risk of overall birth defects, and stillbirths in settings with good existing health records and well defined target populations.

Comparison of pooled risk estimates for adverse effects from different observational study designs: methodological overview

BACKGROUND

A diverse range of study designs (e.g. case-control or cohort) are used in the evaluation of adverse effects. We aimed to ascertain whether the risk estimates from meta-analyses of case-control studies differ from that of other study designs.

METHODS

Searches were carried out in 10 databases in addition to reference checking, contacting experts, and handsearching key journals and conference proceedings. Studies were included where a pooled relative measure of an adverse effect (odds ratio or risk ratio) from case-control studies could be directly compared with the pooled estimate for the same adverse effect arising from other types of observational studies.

RESULTS

We included 82 meta-analyses. Pooled estimates of harm from the different study designs had 95% confidence intervals that overlapped in 78/82 instances (95%). Of the 23 cases of discrepant findings (significant harm identified in meta-analysis of one type of study design, but not with the other study design), 16 (70%) stemmed from significantly elevated pooled estimates from case-control studies. There was associated evidence of funnel plot asymmetry consistent with higher risk estimates from case-control studies. On average, cohort or cross-sectional studies yielded pooled odds ratios 0.94 (95% CI 0.88-1.00) times lower than that from case-control studies.

INTERPRETATION

Empirical evidence from this overview indicates that meta-analysis of case-control studies tend to give slightly higher estimates of harm as compared to meta-analyses of other observational studies. However it is impossible to rule out potential confounding from differences in drug dose, duration and populations when comparing between study designs.

Benzodiazepine exposure in pregnancy and risk of major malformations: a critical overview

OBJECTIVE

Benzodiazepines (BDZs) safety profiles in pregnancy suggest that the risk of major malformations (MMs) cannot be considered simply as a "class effect". The aim of this paper was to review and update the available literature on the risks of MMs in women exposed to BDZs in the first trimester of pregnancy.

METHODS

PubMed was searched for English-language articles, from January 2001 to November 2011, introducing as keywords "teratogens", " major malformation", "foetus", "infant", "newborn", "pregnancy", in conjunction with "benzodiazepines" as a keyword or BDZ generic name as text words.

RESULTS

Twelve studies were selected for the review. BDZ exposure during the first trimester of pregnancy seems not to be associated with an increasing risk of congenital MMs. Diazepam and chlordiazepoxide should be considered drugs of first choice.

CONCLUSIONS

Data published in the last 10 years did not indicate an absolute contraindication in prescribing BDZs during the first gestational trimester. In any case, studies analyzed suffer from a number of methodological limitations such as lack of careful report of BDZ patterns of use in pregnancy, possible influences of recall bias, lack of controlling for confounding factors and lack of data concerning possible MMs in aborted fetuses.

Pregnancy outcome after gestational exposure to erythromycin - a population-based register study from Norway

AIMS

Erythromycin is a macrolide antibiotic indicated for respiratory tract infections, genital chlamydia and skin infections. It has recently been suggested that erythromycin use in the first trimester of pregnancy can increase the risk of congenital cardiovascular malformations. This study aimed to determine whether erythromycin exposure in the first trimester is associated with cardiovascular or other malformations.

METHODS

We studied 180 120 women in Norway who were pregnant during 2004-2007. Data on all live births stillbirths and induced abortions after 12 gestational weeks from The Medical Birth Registry of Norway (MBRN) were linked to information from the Norwegian prescription database (NorPD). We compared the pregnancy outcomes of women who had taken erythromycin (n= 1786, 1.0%), penicillin V (n= 4921, 2.7%) or amoxicillin (n= 1599, 0.9%) in their first trimester with outcomes of women who had not taken any systemic antibiotics (n= 163 653, 90.9%) during this period.

RESULTS

The risk of cardiovascular malformations was not significantly different with or without exposure to erythromycin in the first trimester (adjusted OR = 1.2 [95% CI 0.8, 1.8]) or in the most vulnerable period of heart formation (adjusted OR = 1.6 [95% CI 0.9-3.0]). Sub-analyses showed that the risk for any specific malformations was not increased with erythromycin, macrolides, penicillin V or amoxicillin compared with no antibiotic use in first trimester.

CONCLUSIONS

This large, population-based register study did not find that exposure to erythromycin or macrolides in the first trimester of pregnancy was associated with fetal cardiovascular or other malformations. These results suggest that the risk of erythromycin use during early pregnancy, if any, is low.

Drugs and Birth Defects: a knowledge database providing risk assessments based on national health registers

PURPOSE

To present concept, methods and use of a knowledge database providing assessments of potential fetal risks for all drugs on the Swedish market.

METHODS

Assessments of fetal risks are made primarily by analyzing prospective epidemiological data from the Swedish Medical Birth Register on drug intake in relation to birth outcome. This is complemented by evaluation of the scientific literature. Following standardized working procedures, a statement is compiled for each substance, which is also classified into one of three categories depending on the estimated risk level. The final documents include drug product names on the market, via linkage to a medicinal products register. The information is free and published on the website www.janusinfo.se . It can also be used as an integrated part of electronic health records.

RESULTS

The database covers assessments of fetal risks for close to 1,250 medicinal drug substances on the Swedish market. Each year, 96,000 searches are made, which might be compared to the around 100,000 children born in Sweden yearly. Apart from the Swedish Physicians' Desk Reference (Fass), the database is the most commonly used resource among specialists within gynaecology and perinatal medicine for information on drugs during pregnancy.

CONCLUSIONS

A non-commercial knowledge base with assessments of fetal risk of different drugs is valued by health care professionals and is used extensively in Sweden. Based on analyses of national health registers, the database provides unique information on teratogenic drug risks.

Approaching Parents to Take Part in a Cleft Gene Bank: A Qualitative Pilot Study

Objective

A gene bank, comprising genetic material and environmental and family history data, is being established in the United Kingdom to improve the understanding of the etiology of orofacial clefting (OFC). This study aimed to identify factors that might contribute to participation in a cleft gene bank and what issues need to be considered in approaching parents to be included.

Design

A qualitative approach was adopted, using focus groups and interviews. Transcripts of audio recordings were analyzed using inductive thematic analysis.

Participants

A UK cleft center invited 100 families of children born with OFC to participate. Inclusion criteria included any parent of a child aged between 6 months and 16 years willing to take part. Sixteen parents participated.

Results

Participants were generally motivated to take part in a cleft gene bank because they value the discovery of new knowledge of the etiology of OFC. They wanted reassurance about the purpose and integrity of the project. Many conveyed shock at the diagnosis of cleft and offered mixed accounts of experiences with health care professionals. They suggested an individualized approach from a trustworthy and sensitive professional when being invited to join the gene bank, avoiding difficult times associated with new-baby challenges and issues related to the cleft.

Conclusions

This pilot study indicates that parents of children born with OFC would be supportive of developing a cleft gene bank, but sensitive issues need to be considered.

Early morbidity and mortality following in utero exposure to selective serotonin reuptake inhibitors: a population-based study in Western Australia

BACKGROUND

The early years of life have a profound effect on a child's developmental pathway. The children born to mothers suffering from depression may be at risk of increased morbidity and mortality in the first years of life.

OBJECTIVE

The objective of this study was to investigate the hospital admissions and mortality of children whose mothers were dispensed a selective serotonin reuptake inhibitor (SSRI) during their pregnancy.

METHODS

This was a population-based study of all pregnancy events in Western Australia (WA) from 2002 to 2005. The study used linkable state health administrative data from the WA Data Linkage System (WADLS) and the national Pharmaceutical Benefits Scheme (PBS), enabling birth outcomes, hospital admissions and deaths to be ascertained for the children of women dispensed an SSRI during their pregnancy.

RESULTS

There were 3764 children born to 3703 women who had been dispensed an SSRI during their pregnancy (3.8% of all pregnancies in WA, 2002-5), and 94 561 children born to 92 995 women who had not been dispensed an SSRI. Mean birth weight, length and APGAR score at 5 minutes were significantly lower in children of women dispensed an SSRI, regardless of whether the SSRI was dispensed in trimester 1, or, trimester 2 or 3 only. 0.9% of the live born children in the SSRI group had died before the age of 1 year compared with 0.5% of the non-SSRI group (odds ratio [OR] 1.8; 95% CI 1.3, 2.6). Before the age of 2 years, 42.9% of the children in the SSRI group had been admitted to hospital after their birth admission, compared with 34.1% of the non-SSRI group (OR 1.4; 95% CI 1.3, 1.6). The most common reason for admission to hospital was acute bronchiolitis (OR 1.6; 95% CI 1.3, 1.8), with an increased risk seen in children of mothers who did not smoke during their pregnancy (OR 1.7; 95% CI 1.4, 2.0).

CONCLUSIONS

The children in the SSRI group were more likely to be admitted to hospital in the first years of life, and this may reflect their prenatal exposure to SSRIs, be related to maternal depression, or SSRI use may be a proxy for an environmental exposure such as smoking, or a combination of these factors. Although the numbers of deaths in the first year of life were small, the increased risk of death in the first year of life in the SSRI group (OR 1.8; 95% CI 1.3, 2.6) is a new finding and should be investigated further.

The problem of confounding in studies of the effect of maternal drug use on pregnancy outcome

In most epidemilogical studies, the problem of confounding adds to the uncertainty in conclusions drawn. This is also true for studies on the effect of maternal drug use on birth defect risks. This paper describes various types of such confounders and discusses methods to identify and adjust for them. Such confounders can be found in maternal characteristics like age, parity, smoking, use of alcohol, and body mass index, subfertility, and previous pregnancies including previous birth of a malformed child, socioeconomy, race/ethnicity, or country of birth. Confounding by concomitant maternal drug use may occur. A geographical or seasonal confounding can exist. In rare instances, infant sex and multiple birth can appear as confounders. The most difficult problem to solve is often confounding by indication. The problem of confounding is less important for congenital malformations than for many other pregnancy outcomes.

Rheumatoid arthritis and pregnancy: evolution of disease activity and pathophysiological considerations for drug use

It has long been known that pregnancy and childbirth have a profound effect on the disease activity of rheumatic diseases. For clinicians, the management of patients with RA wishing to become pregnant involves the challenge of keeping disease activity under control and adequately adapting drug therapy during pregnancy and post-partum. This article aims to summarize the current evidence on the evolution of RA disease activity during and after pregnancy and the use of anti-rheumatic drugs around this period. Of recent interest is the potential use of anti-TNF compounds in the preconception period and during pregnancy. Accumulating experience with anti-TNF therapy in other immune-mediated inflammatory diseases, such as Crohn's disease, provides useful insights for the use of TNF blockade in pregnant women with RA, or RA patients wishing to become pregnant.

Meta-analyses of adverse effects data derived from randomised controlled trials as compared to observational studies: methodological overview

BACKGROUND

There is considerable debate as to the relative merits of using randomised controlled trial (RCT) data as opposed to observational data in systematic reviews of adverse effects. This meta-analysis of meta-analyses aimed to assess the level of agreement or disagreement in the estimates of harm derived from meta-analysis of RCTs as compared to meta-analysis of observational studies.

METHODS AND FINDINGS

Searches were carried out in ten databases in addition to reference checking, contacting experts, citation searches, and hand-searching key journals, conference proceedings, and Web sites. Studies were included where a pooled relative measure of an adverse effect (odds ratio or risk ratio) from RCTs could be directly compared, using the ratio of odds ratios, with the pooled estimate for the same adverse effect arising from observational studies. Nineteen studies, yielding 58 meta-analyses, were identified for inclusion. The pooled ratio of odds ratios of RCTs compared to observational studies was estimated to be 1.03 (95% confidence interval 0.93-1.15). There was less discrepancy with larger studies. The symmetric funnel plot suggests that there is no consistent difference between risk estimates from meta-analysis of RCT data and those from meta-analysis of observational studies. In almost all instances, the estimates of harm from meta-analyses of the different study designs had 95% confidence intervals that overlapped (54/58, 93%). In terms of statistical significance, in nearly two-thirds (37/58, 64%), the results agreed (both studies showing a significant increase or significant decrease or both showing no significant difference). In only one meta-analysis about one adverse effect was there opposing statistical significance.

CONCLUSIONS

Empirical evidence from this overview indicates that there is no difference on average in the risk estimate of adverse effects of an intervention derived from meta-analyses of RCTs and meta-analyses of observational studies. This suggests that systematic reviews of adverse effects should not be restricted to specific study types. Please see later in the article for the Editors' Summary.

Antidepressant use during pregnancy: comparison of data obtained from a prescription register and from antenatal care records

PURPOSE

To compare interview data on drug use during pregnancy with data identified from a register of prescriptions.

MATERIALS

We compared information from the Swedish Prescribed Drug Register with the Swedish Medical Birth Register on antidepressant use. In order to evaluate the clinical significance of the difference in ascertainment with the two methods, the rate of preterm births among singletons and of neonatal symptoms were studied.

RESULTS

During the year before the last menstrual period, 1.5% of the women filled prescriptions for antidepressants each month. Already before the pregnancy was known, the rate of filled prescriptions decreased and reached 0.5% towards the end of the pregnancy. Twenty-two percent of first-trimester use of antidepressants was unidentified using interview data and prescriptions during the 2nd and 3rd pregnancy months covered only 55% of actual use. When women who filled prescriptions 1 or 3 months before the last menstrual period were included, 17 and 43% respectively of women were included who probably did not use the drugs in the first trimester. Prescriptions gave a more complete ascertainment of drug use after the first trimester than data from antenatal care, which seemed to overestimate drug use.

CONCLUSIONS

Interview data seem to give the most valid results on early use. When interview data are not available, prescription data could be used, but should not include prescriptions given earlier than 1 month before the last menstrual period. Studies of drug use later in pregnancy are best based on prescription data in the absence of interview data.

Drug use during pregnancy in Sweden - assessed by the Prescribed Drug Register and the Medical Birth Register

Purpose:

The purpose of this research is to study drug use during pregnancy in Sweden and agreement between use according to antenatal medical records and dispensed drugs from a pharmacy database.

Patients and methods:

From the Swedish Medical Birth Register (MBR), we established a population-based cohort of 102,995 women who gave birth in 2007. Using the unique personal registration number, information on dispensed drugs from the Prescribed Drug Register (PDR) was obtained prior to, during, and after the pregnancies and compared with MBR information on drug use from standardized antenatal medical records.

Results:

According to the PDR, 57.6% of the 102,995 women filled a prescription with at least one drug during pregnancy and 50.9% during the lactating period (until 3 months after delivery). The most dispensed drugs during pregnancy were B-lactam antibacterials and penicillins. Agreement between drugs recorded in antenatal medical records and dispensed drugs was highest for drugs used for chronic conditions. The agreement was particularly high for thyroid therapy (85.3%), anti-intestinal inflammatory drugs (80.3%), antiepileptics (69.2%), immunosuppressants (67.4%), and insulin (63.8%). Agreement for drugs used for occasional use was generally lower, ranging between 42.5% for antihistamines and 0.8% for gynecological anti-infectives.

Conclusions:

A large proportion of women filled a prescription during pregnancy or the lactating period. Agreement between drug use in medical antenatal records and register information from a national pharmacy database was high for drugs used for chronic conditions but low for occasional use. For occasionally used drugs, medical record and register-based data may provide incomplete exposure information because of nonreporting or noncompliance.

Delivery outcome after maternal use of antidepressant drugs in pregnancy: an update using Swedish data

BACKGROUND

Concerns have been expressed about possible adverse effects of the use of antidepressant medication during pregnancy, including risk for neonatal pathology and the presence of congenital malformations.

METHOD

Data from the Swedish Medical Birth Register (MBR) from 1 July 1995 up to 2007 were used to identify women who reported the use of antidepressants in early pregnancy or were prescribed antidepressants during pregnancy by antenatal care: a total of 14 821 women with 15 017 infants. Maternal characteristics, maternal delivery diagnoses, infant neonatal diagnoses and the presence of congenital malformations were compared with all other women who gave birth, using the Mantel-Haenszel technique and with adjustments for certain characteristics.

RESULTS

There was an association between antidepressant treatment and pre-existing diabetes and chronic hypertension but also with many pregnancy complications. Rates of induced delivery and caesarean section were increased. The preterm birth rate was increased but not that of intrauterine growth retardation. Neonatal complications were common, notably after tricyclic antidepressant (TCA) use. An increased risk of persistent pulmonary hypertension of the newborn (PPHN) was verified. The congenital malformation rate was increased after TCAs. An association between use of paroxetine and congenital heart defects was verified and a similar effect on hypospadias was seen.

CONCLUSIONS

Women using antidepressants during pregnancy and their newborns have increased pathology. It is not clear how much of this is due to drug use or underlying pathology. Use of TCAs was found to carry a higher risk than other antidepressants and paroxetine seems to be associated with a specific teratogenic property.

Non-genetic risk factors for holoprosencephaly

Holoprosencephaly (HPE) is a congenital defect of the brain characterized by incomplete cleavage of the embryonic forebrain into left and right hemispheres. Although a substantial proportion of cases of HPE can be attributed to genetic abnormalities, the etiology in many cases remains unknown, with non-genetic risk factors believed to be important contributors. Due to the low birth prevalence of this defect, it has proven difficult to conduct studies of sufficient size to identify risk factors with certainty. This article provides a summary of non-genetic risk factors for HPE that have been investigated in case reports and case series, animal studies, and epidemiologic studies, including maternal illnesses, therapeutic and non-therapeutic exposures, nutritional factors, and sociodemographic factors. The article also highlights challenges in study design and further areas for research to better understand the etiology of HPE.

Pattern of drug use during the first trimester among Chinese women: data from a population-based cohort study

AIM

To describe the pattern of drug use among Chinese women during the first trimester and to examine the impact of maternal diseases on the choice of drugs.

METHOD

This drug utilisation study of pregnant women was performed using data from the ABCD cohort study. A total of 4,290 women were enrolled in the analysis. Information was collected by self-completion questionnaire combined with the "Maternal health handbook".

RESULTS

Of the 4,290 women interviewed, 75.9% of women took at least one drug during the first trimester. Users took a mean number of 1.43 drugs. The most frequently used drugs were folic acid (65.2%), vitamins (14.6%), calcium (12.0%), minerals (11.1%), Chinese traditional patent medicine (CTPM; 10.1%) and anti-infectives (6.5%). Among the women having used CTPM, influenza/cold and threatened abortion were the most commonly reported indications. Logistic regression analysis of drug use (excluding nutritional and haematological drugs) shows that CTPM and Western medicine are both associated with the use of drugs for occasional diseases and against threatened abortion. Maternal chronic diseases were not associated with the use of CTPM.

CONCLUSION

This analysis of pregnant women showed that drugs were prescribed to most women, even when nutritional and haematological drugs were excluded. Our data reflect, except for drugs used for chronic diseases, a general reluctance among Chinese women to use Western medicine and resorting to CTPM during pregnancy.

Antihypertensive medication use during pregnancy and the risk of cardiovascular malformations

We used data from the National Birth Defects Prevention Study, a population-based, case-control study, to examine whether previously reported associations between antihypertensive medications and cardiovascular malformations could be confirmed and to explore whether new associations might be identified. Cases (n=5021) were ascertained through birth defects surveillance systems from 1997 through 2003 in 10 US states. Controls (n=4796) were live births without birth defects selected randomly from birth certificates or hospital discharge listings in the same geographic regions. Logistic regression was used to examine the relationship between antihypertensive medication treatment and the occurrence of cardiovascular malformations while controlling for confounding variables. First-trimester treatment with antihypertensive medication was associated with pulmonary valve stenosis (odds ratio [OR]: 2.6; 95% CI: 1.3 to 5.4), Ebstein malformation (crude OR: 11.4; exact 95% CI: 2.8 to 34.1), coarctation of the aorta (OR: 3.0; 95% CI: 1.3 to 6.6), and secundum atrial septal defects (OR: 2.4; 95% CI: 1.3 to 4.4). Treatment initiated after the first trimester was associated with pulmonary valve stenosis (OR: 2.4; 95% CI: 1.1 to 5.4), perimembranous ventricular septal defects (OR: 2.3; 95% CI: 1.2 to 4.6), and secundum atrial septal defects (OR: 2.4; 95% CI: 1.3 to 4.4). Untreated hypertension was associated with Ebstein malformation (OR: 2.1; 95% CI: 1.0 to 4.3) and secundum atrial septal defects (OR: 1.3; 95% CI: 1.0 to 1.6). Antihypertensive medication use and/or the underlying hypertension might increase the risk of having an infant with specific left and right obstructive and septal defects. Additional studies with adequate power will be needed to confirm these findings.

Use of herbal drugs during early pregnancy in relation to maternal characteristics and pregnancy outcome

PURPOSE

To study characteristics of women using herbal drugs and the possible impact of use in early pregnancy on pregnancy outcome.

METHODS

Data on the use of herbal drugs during pregnancy were obtained from the Swedish Medical Birth Register during the period 1st July 1995 to end of 2004. Women who reported use of herbal drugs were compared to all women giving birth during the period. Outcome variables were prematurity, birth weight, Apgar score, number of infants in delivery and congenital malformations.

RESULTS

Among the 860 215 women in the register, 787 (0.9%) reported use of herbal drugs during early pregnancy. The most frequently used herbal drugs were Floradix (iron-rich herbs), ginseng and valerian. Use of such drugs was independently associated with high maternal age, normal weight and 14-15 years of education. Risk factors for valerian differed from those for other herbal drugs, for example with respect to maternal smoking and country of birth. Concomitant drug use was common and the most frequently used drugs were multivitamins, folic acid, cardiovascular drugs (mainly antihypertensive drugs), non-steroid anti-inflammatory drugs (NSAIDs), analgesics and psycholeptics. None of the infant characteristics studied were influenced significantly by the mother's use of the examined herbal drugs during early pregnancy.

CONCLUSIONS

The most commonly reported herbal drugs used during pregnancy were Floradix (iron-rich herbs), ginseng and valerian. No signs of unfavourable effect on pregnancy outcome were seen. The number of exposures, however, was low and therefore effects on rare outcomes (e.g. specific malformations) cannot be excluded.

Prescription drug use among fathers and mothers before and during pregnancy. A population-based cohort study of 106,000 pregnancies in Norway 2004-2006

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Mothers are using medicines during pregnancies; the extent varies across the world and is generally difficult to compare. In this registry-based study, we examined more than 100,000 Norwegian pregnancies and described the drug prescription pattern of both fathers and mothers around conception and during pregnancy (mothers).

WHAT THIS STUDY ADDS

In every trimester of pregnancy, about 30% of the mothers was dispensed a drug. The total drug exposure did not seem to diminish throughout pregnancy. One-quarter of the fathers was dispensed drugs during the last 3 months prior to conception.

AIMS

The primary aim of this study was to describe the use of prescribed drugs in both mothers and fathers before and during pregnancy in Norway.

METHODS

This population-based cohort study was based on data retrieved from the Medical Birth Registry of Norway and the Norwegian Prescription Database. These registries cover the entire population of Norway. Information on >100,000 births during 2004-2006 in the birth registry was linked to prescription data. Prescriptions issued to mothers just prior to, during and after the pregnancies as well as prescriptions to fathers just prior to conception were identified.

RESULTS

Among mothers, 83% were prescribed drugs during the period 3 months prior to estimated conception until 3 months after giving birth. The mothers who received drugs were prescribed on average 3.3 different Anatomical Therapeutic Chemical (ATC) codes (range 1-38). During pregnancy, 57% were prescribed drugs. In the first trimester, 33% of mothers were dispensed drugs, while the figure was 29% for mothers in the last trimester. Among fathers, 25% used prescribed drugs during the 3 months prior to conception, with on average 1.9 different ATC codes (range 1-22).

CONCLUSION

Large proportions of both fathers and mothers were dispensed drugs prior to conception or during pregnancy. While there is a high awareness of the issues involved in maternal drug use in pregnancy, possible teratogenic effects of drug use in fathers shortly before conception should be further explored.

Use of benzodiazepines and benzodiazepine receptor agonists during pregnancy: maternal characteristics

BACKGROUND

Use of benzodiazepine (BZD) drugs or hypnotic benzodiazepine receptor agonists (HBRAs) during pregnancy may represent a hazard for the foetus. In order to analyse this in an adequate way, knowledge of maternal characteristics as putative confounders is needed.

METHODS

In the Swedish Medical Birth Register, 2149 pregnant women using BZDs or HBRAs were identified, 1944 of them in early pregnancy. These women were compared with other women (n = 859 455) giving births during the same period (1 July 1995-31 December 2004). The following maternal characteristics were studied: age, parity, smoking habits, education, previous miscarriages, years of involuntary childlessness as an estimate of subfertility, concomitant drug use and some pregnancy complications.

RESULTS

Use and/or reporting of BZDs or HBRAs increased with maternal age. It was higher at first and 4+ parity and increased markedly with maternal smoking. Women with low education reported a higher use than women with high education. Previous miscarriage or subfertility had little impact on the use of these drugs. Preterm birth and caesarean section (also at term birth) were more common than expected. In women using BZDs or HBRAs, other types of psychoactive drugs were used in excess.

CONCLUSIONS

Women using BZDs or HBRAs differ in many aspects from women not using those drugs. These differences may act as confounders in the analysis of pregnancy outcome.

The safety of antidepressant drugs during pregnancy

This article discusses known or suspected effects of maternal use of antidepressants during pregnancy on pregnancy outcome. It is unlikely that any marked teratogenic effect occurs with the possible exception of an increased risk for cardiovascular defects after maternal use of clomipramine or paroxetine. An increased risk for preterm birth is seen. Transient neonatal symptoms are common after the use of antidepressants in late pregnancy. Few firm data are available on the possible impact on the long-term neuropsychological development of the infants. The magnitude of the actual contribution from drug therapy is unclear; it is likely that the underlying pathology of the mother explains part of the anomalies. Selective serotonin re-uptake inhibitor drugs seem to represent a smaller hazard than tricyclic antidepressants. Further research to separate the effects of the drug and underlying pathology is urgently needed as are large-scale studies on long-term development. When a pregnant woman has a major depressive disease and non-pharmacological treatments are not enough, the relatively small risk with drug therapy has to be weighed against the considerable risk for a relapse of the disease if therapy is interrupted.

Use of antiemetic drugs during pregnancy in Sweden

BACKGROUND

More than one-half of all pregnant women suffer from nausea and vomiting during pregnancy (NVP), primarily during the first trimester.

METHODS

Prospectively ascertained information on drug use during pregnancy was obtained from the Swedish Medical Birth Register during the period July 1, 1995 to 2002. Antiemetics (antiemetic antihistamines, dopamine modulators, and ondansetron) primarily used for NVP were studied, and women reporting the use of these drugs were compared with all women who gave birth during the study period.

RESULTS

Use of these antiemetics was reported in 4.5% of the pregnant women--86% of whom reported their use before the first antenatal visit (usually weeks 10-12). Meclozine, followed by other antihistamines, accounted for 68% of the drugs reported. Young maternal age, multiparity, non-smoking, and a period of unwanted childlessness increased the probability of using any of the antiemetics during pregnancy. Women with a low education used these drugs more often than women with a relatively higher education. Neonates born to women who used any of the antiemetics had a reduced risk for low birthweight, prematurity, being small-for-gestational age, and having a malformation. No specific differences were observed with respect to the outcome following a comparison of different antiemetic drugs.

CONCLUSIONS

Women using antiemetics as a rule have a better delivery outcome than other women, probably due to an effect of a well-functioning placenta, which is associated with NVP. There were no signs of any significant teratogenicity of the drugs studied, but for some drugs the number of exposures was low.