Is there an association between family members' season of birth that could influence birth seasonality? Evidence from Spain and France

The number of births varies by season. Research on birth seasonality has shown that women's season of birth somehow influences that of their children, but factors underlying the intergenerational transmission of birth seasonality remain unknown. With data from Spain and France, we analysed the possibility of transmission of birth season between generations, testing whether relatives tended to be born in the same season. Results indicated that there was an association-a similarity-between parents' and children's birth seasons, partially explaining the stability of seasonal patterns over time. This association also existed between parents' birth seasons. While parents' association is directly explained by an excess of marriages with spouses born in the same month, the overall association may be explained by two facts: different socio-demographic groups show differentiated birth patterns, and relatives share socio-demographic features. Birth season seems to be related to family characteristics, which should be controlled for when assessing birth-month effects on subsequent social/health outcomes.

Adverse birth outcomes in New York City women: Revisiting the Hispanic Paradox

In the United States, African American or non-Hispanic Black infants experienced worst birth outcomes whereas Hispanic and Asian infants have intermediate or similar outcomes compared with non-Hispanic white infants. The findings of better birth outcomes for Hispanic women have been coined the "Hispanic Paradox" given their low education, income, and access to care. New York City (NYC) has a great racial/ethnic diversity with implications for neighborhood racial/ethnic composition on birth outcomes by protecting women from psychosocial stress via social support that may buffer against racial/ethnic discrimination and/or racism. Data from 2012 to 2018 were used to examine the association of NYC women's race/ethnicity and neighborhood racial/ethnic minority composition with adverse birth outcomes (low birthweight [LBW], small for gestational age [SGA], preterm birth and infant mortality); and whether the association between mother's race/ethnicity and each birth outcome differed by neighborhood racial/ethnic composition. Multilevel logistic regression was used to control for the clustering of outcomes within neighborhoods. Black, Asian, and American Indian women have poorer birth outcomes than white women. Infants of Mexican American, Central American, and South American women were less likely to be of LBW whereas the opposite was true for infants of Cuban and other Hispanic women compared with infants of white women. When compared with white women, Mexican American, and South American women were less likely to have an SGA infant whereas Puerto Rican and other Hispanic women were more likely to have an SGA infant. All Hispanic women were more likely to have a preterm birth than white women whereas for infant mortality, greater odds of dying were observed for infants of Puerto Rican, Dominican, and other Hispanic women. Higher neighborhood racial/ethnic minority composition was associated with greater odds of having an adverse outcome. Finally, we observed heterogeneity of the associations between mother's race/ethnicity and birth outcomes by neighborhood racial/ethnic minority composition.

Influence of sociodemographic factors in birth seasonality in Spain

OBJECTIVES

The goal of the present research is to establish for the first time a hierarchy of sociodemographic factors according to their importance influencing birth seasonality.

METHODS

We used Vital Statistics data on all births registered in Spain in the period 2016-2019. Differences in the degree of seasonality between sociodemographic groups (defined by maternal age, maternal marital status, maternal education, birth order, maternal job qualification, maternal employment status, maternal location population size, and maternal country of birth) were first examined with descriptive techniques. Secondly, analysis through alternative Data Mining techniques determined the association between sociodemographic factors and birth seasonality and the factors importance rank.

RESULTS

Those factors related to maternal labor status (employment status, job qualification, and education) were found to be the most relevant influencing birth seasonality. It was found that the overall seasonal pattern in Spain was driven by lower skilled employed mothers, in contrast with not employed or high skilled employed mothers, who showed a different or weaker seasonality. Finally, we found that a change in the rhythm pattern has taken place in the last decades in Spain.

CONCLUSIONS

Birth seasonality is to a large extent related to maternal employment status. Employed mothers, normally more affected by the seasonality of work calendar than the unemployed, show higher conception rates structured around holidays. This may indicate that the observed change of seasonal pattern in Spain in the last decades, as in other European countries, may be specifically driven by the progressive higher participation of women in labor market.

Selective Serotonin Reuptake Inhibitors and Risk of Noncardioembolic Ischemic Stroke: A Nested Case-Control Study

BACKGROUND

Multiple studies have reported that the use of selective serotonin reuptake inhibitors (SSRIs) is associated with an increased risk of ischemic stroke; however, this finding may be the result of a confounding by indication. We examined the association using different approaches to minimize such potential bias.

METHODS

A nested case-control study was carried out in a Spanish primary health-care database over the study period 2001 to 2015. Cases were patients sustaining an ischemic stroke with no sign of cardioembolic or unusual cause. For each case, up to 5 matched controls (for exact age, sex, and index date) were randomly selected. Antidepressants were divided in 6 pharmacological subgroups according to their mechanism of action. The current use of SSRIs (use within a 30-day window before index date) was compared with nonuse, past use (beyond 365 days) and current use of other antidepressants through a conditional logistic regression model to obtain adjusted odds ratios and 95% CI. Only initiators of SSRIs and other antidepressants were considered.

RESULTS

A total of 8296 cases and 37 272 matched controls were included. Of them, 255 (3.07%) were current users of SSRIs among cases and 834 (2.24%) among controls, yielding an adjusted odds ratio of 1.14 (95% CI, 0.97-1.34) as compared with nonusers, 0.94 (95% CI, 0.77-1.13) as compared with past-users and 0.74 (95% CI, 0.58-0.93) as compared with current users of other antidepressants. No relevant differences were found by duration (≤1, >1 year), sex, age (<70, ≥70 years old) and background vascular risk.

CONCLUSIONS

The use of SSRIs was not associated with an increased risk of noncardioembolic ischemic stroke. On the contrary, as compared with other antidepressants, SSRIs appeared to be protective.

Overview of equity in maternal health care coverage by ethnicity

Background

Indigenous women are one of the most vulnerable groups in Latin America. They experience substantially worse maternal health outcomes than most of the population and less likely to benefit from services. Therefore, inequities in maternal health care between different ethnic groups should be monitored to identify critical factors that could limit health care coverage.

Methods

Cross-sectional analysis of the continuum of maternal health care, the indicators covering the continuum of women's care from pregnancy to the puerperium were estimated. We used nationally representative demographic surveys from Bolivia, Guatemala, Mexico, and Peru (2008-2016) to explore the coverage gaps across maternal health care by ethnicity. Women were classified as indigenous through self-identification, and we measured a relative inequality by ethnicity through the estimation of adjusted coverage ratios (CR), CR = 1 means that the coverage is equal between indigenous and non-indigenous. We estimated the CR with Poisson regression models adjusted for sociodemographic variables.

Results

Indigenous women in all four countries had less coverage than non-indigenous in the continuum of maternal healthcare. The most relevant inequalities occur in the coverage of skilled-birth-attendant and in the use of contraceptives, mainly for Bolivia [CR = 0.64, p &lt; 0.001; CR = 0.91, p &lt; 0.001] and Guatemala [CR = 0.78, p &lt; 0.001; 0.77 (0.73;0.80), p &lt; 0.001]. Peru and Mexico are the countries with the smallest gaps throughout the continuum care and Guatemala with the largest.

Conclusions

The differences observed reflect the inequities that indigenous women face in the coverage of maternal health care. Therefore, it is useful and necessary to monitor ethnicity inequalities to identify the factors that limit the coverage of care that indigenous women receive to design culturally appropriate programs and policies to reduce the risks of maternal mortality and the inequities in care that indigenous women face.

Key messages

As long as the inequalities persist, identifying them will be the first step in their elimination. If not reduce the differences in care, it will be difficult to reduce maternal mortality that indigenous women face.

Differential effects of antidepressant subgroups on risk of acute myocardial infarction: A nested case-control study

The primary objective of this study was to investigate the association between antidepressants use and the risk of acute myocardial infarction (AMI).

METHODS

We conducted a nested case-control study using a primary care database over the period 2002-2015. From a cohort of patients aged 40-99 years, we identified incident AMI cases and randomly selected 5 controls per case, matched to cases for exact age, sex and index date. Exposure to antidepressants were categorised as current, recent, past and nonusers. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were computed using conditional logistic regression to assess the association between the current use of different antidepressants subgroups and AMI as compared to nonuse. Dose and duration effects were explored.

RESULTS

Totals of 24 155 incident AMI cases and 120 775 controls were included. The current use of antidepressants as a group was associated with a reduced risk (AOR = 0.86; 95% CI: 0.81-0.91), but mainly driven by selective serotonin reuptake inhibitors (AOR = 0.86; 95% CI:0.81-0.93). A reduced risk was also observed with trazodone (AOR = 0.76;95% CI: 0.64-0.91), and clomipramine (AOR = 0.62; 95% CI: 0.40-0.96), whereas no significant effect was observed with other antidepressants. A duration-dependent effect was suggested for selective serotonin reuptake inhibitors, trazodone and clomipramine, while there was no clear dose-dependency.

CONCLUSION

This study suggests that current use of antidepressants interfering selectively with the reuptake of serotonin, and those antagonizing the 5-HT_2A receptor, are associated with a decrease in AMI risk and should be the antidepressants of choice in patients at cardiovascular risk.

How the choice of ethnic indicator influences ethnicity-based inequities in maternal health care in four Latin American countries: who is indigenous?

Background

The current focus on monitoring health inequalities and the complexity around ethnicity requires careful consideration of how ethnic disparities are measured and presented. This paper aims to determine how inequalities in maternal healthcare by ethnicity change according to different criteria used to classify indigenous populations.

Methods

Nationally representative demographic surveys from Bolivia, Guatemala, Mexico, and Peru (2008–2016) were used to explore coverage gaps across maternal health care by ethnicity using different criteria. Women were classified as indigenous through self-identification (SI), spoken indigenous language (SIL), or indigenous household (IH). We compared the gaps through measuring coverage ratios (CR) with adjusted Poisson regression models.

Results

Proportions of indigenous women changed significantly according to the identification criterion (Bolivia:SI-63.1%/SIL-37.7%; Guatemala:SI-49.7%/SIL-28.2%; Peru:SI-34%/SIL-6.3% & Mexico:SI-29.7%/SIL-6.9%). Indigenous in all countries, regardless of their identification, had less coverage. Gaps in care between indigenous and non-indigenous populations changed, for all indicators and countries, depending on the criterion used (e.g., Bolivia CR for contraceptive-use SI = 0.70, SIL = 0.89; Guatemala CR for skilled-birth-attendant SI = 0.77, SIL = 0.59). The heterogeneity persists when the reference groups are modified and compare just to non-indigenous (e.g., Bolivia CR for contraceptive-use under SI = 0.64, SIL = 0.70; Guatemala CR for Skilled-birth-attendant under SI = 0.77, SIL = 0.57).

Conclusions

The indigenous identification criteria could have an impact on the measurement of inequalities in the coverage of maternal health care. Given the complexity and diversity observed, it is not possible to provide a definitive direction on the best way to define indigenous populations to measure inequalities. In practice, the categorization will depend on the information available. Our results call for greater care in the analysis of ethnicity-based inequalities. A greater understanding on how the indigenous are classified when assessing inequalities by ethnicity can help stakeholders to deliver interventions responsive to the needs of these groups.

Obstacles and opportunities for monitoring ethnicity-based inequalities in maternal health care: Lessons from Mexico

BACKGROUND

Monitoring and reducing inequalities in health care has become more relevant since the adoption of the Sustainable Development Goals (SDGs). The SDGs bring an opportunity to put the assessment of inequalities by ethnicity on the agenda of decision-makers. The objective of this qualitative study is to know how current monitoring is carried out and to identify what factors influence the process in order to incorporate indicators that allow the evaluation of inequalities by ethnicity.

METHODS

We conducted 17 semi-structured interviews with key informants from the health ministry, monitoring observatories, research centers, and international organizations, involved in maternal health care monitoring in Mexico. Our analysis was interpretative-phenomenological and focused on examining experiences about monitoring maternal health care in order to achieve a full picture of the current context in which it takes place and the factors that influence it.

RESULTS

The obstacles and opportunities pointed out from the participants emerge from the limitations or advantages associated with the accuracy of evaluation, availability of information and resources, and effective management and decision-making. Technicians, coordinators, researchers or decision-makers are not only aware of the inequalities but also of its importance. However, this does not lead to political decisions permitting an indicator to be developed for monitoring it. As for opportunities, the role of international organizations and their links with the countries is crucial to carry out monitoring, due to political and technical support.

CONCLUSIONS

The success of a monitoring system to help decision-makers reduce inequalities in health care depends not only on accurate evaluations but also on the context in which it is implemented. Understanding the operation, obstacles and opportunities for monitoring could be a key issue if the countries want to advance towards assessing inequalities and reducing health inequities with the aid of concrete policies and initiatives.

Missing girls among deliveries from Indian and Chinese mothers in Spain 2007-2015

Deliveries from Indian and Chinese mothers present a higher than expected male:female ratio in their own countries, in northern Europe, EEUU and Canada. No studies have been carried out in southern European countries. We explored whether the high male-to-female ratio common in Indian and Chinese communities, also exists among families from those regions who live in Spain. For that purpose we designed a cross-sectional population-based study containing data on 3,133,908 singleton live births registered in the Spanish Vital Statistics Registry during the period 2007-2015. The ratio of male:female births by area of origin was calculated using binary intercept-only logistic regression models without reference category for the whole sample of births and taking into account a possible effect modification of birth order and sex of the previous males. Interaction effects of sociodemographic mothers' and fathers' characteristics was also assesed. In Spain, the ratio male:female is higher than expected for Indian-born mothers, especially for deliveries from mothers with no previous male births and, to a lesser extent, for Chinese-born women, specifically for third or higher order births and slightly influenced by the sex of the previous births. Therefore, the increased sex male:female ratio observed in other countries among Indian and Chinese mothers is also observed in Spain. This reinforces the notion that culture and values of the country of origin are more influential than the country of residence.

Indigenous language and inequitable maternal health care, Guatemala, Mexico, Peru and the Plurinational State of Bolivia

Latin America and the Caribbean still have high maternal mortality rates and access to health care is very uneven in some countries. Indigenous women, in particular, have poorer maternal health outcomes than the majority of the population and are less likely to benefit from health-care services. Therefore, inequities in maternal health between different ethnic groups should be monitored to identify critical factors that could limit health-care coverage. In adopting the United Nations’ sustainable development goals, governments have committed to providing equitable and universal health coverage. It is, therefore, the right time to assess ethnic disparities in maternal health care. However, finding a standard method of identifying ethnicity has been difficult, because ethnicity involves several features, such as language, religion, tribe, territory and race. In this study, spoken indigenous language was used successfully as a proxy for ethnicity to detect inequities in maternal health-care coverage between indigenous and non-indigenous populations in four Latin American countries: Guatemala, Mexico, Peru and the Plurinational State of Bolivia. Although, quantifying ethnic inequities in health care is just a starting point, this quantification can help policy-makers and other stakeholders justify the need for monitoring these inequities. This monitoring is essential for designing more culturally appropriate programmes and policies that will reduce the risks associated with maternity among indigenous woman. As long as inequities persist, identifying them is an important step towards their elimination.

Comparison of two methods to estimate adverse events in the IBEAS Study (Ibero-American study of adverse events): cross-sectional versus retrospective cohort design

BACKGROUND

Adverse events (AEs) epidemiology is the first step to improve practice in the healthcare system. Usually, the preferred method used to estimate the magnitude of the problem is the retrospective cohort study design, with retrospective reviews of the medical records. However this data collection involves a sophisticated sampling plan, and a process of intensive review of sometimes very heavy and complex medical records. Cross-sectional survey is also a valid and feasible methodology to study AEs.

OBJECTIVES

The aim of this study is to compare AEs detection using two different methodologies: cross-sectional versus retrospective cohort design.

SETTING

Secondary and tertiary hospitals in five countries: Argentina, Colombia, Costa Rica, Mexico and Peru.

PARTICIPANTS

The IBEAS Study is a cross-sectional survey with a sample size of 11 379 patients. The retrospective cohort study was obtained from a 10% random sample proportional to hospital size from the entire IBEAS Study population.

METHODS

This study compares the 1-day prevalence of the AEs obtained in the IBEAS Study with the incidence obtained through the retrospective cohort study.

RESULTS

The prevalence of patients with AEs was 10.47% (95% CI 9.90 to 11.03) (1191/11 379), while the cumulative incidence of the retrospective cohort study was 19.76% (95% CI 17.35% to 22.17%) (215/1088). In both studies the highest risk of suffering AEs was seen in Intensive Care Unit (ICU) patients. Comorbid patients and patients with medical devices showed higher risk.

CONCLUSION

The retrospective cohort design, although requires more resources, allows to detect more AEs than the cross-sectional design.

The current deconstruction of paradoxes: one sign of the ongoing methodological "revolution"

The current deconstruction of paradoxes is one among several signs that a profound renewal of methods for clinical and epidemiological research is taking place; perhaps for some basic life sciences as well. The new methodological approaches have already deconstructed and explained long puzzling apparent paradoxes, including the (non-existent) benefits of obesity in diabetics, or of smoking in low birth weight. Achievements of the new methods also comprise the elucidation of the causal structure of long-disputed and highly complex questions, as Berkson's bias and Simpson's paradox, and clarifying reasons for deep controversies, as those on estrogens and endometrial cancer, or on adverse effects of hormone replacement therapy. These are signs that the new methods can go deeper and beyond the methods in current use. A major example of a highly relevant idea is: when we condition on a common effect of a pair of variables, then a spurious association between such pair is likely. The implications of these ideas are potentially vast. A substantial number of apparent paradoxes may simply be the result of collider biases, a source of selection bias that is common not just in epidemiologic research, but in many types of research in the health, life, and social sciences. The new approaches develop a new framework of concepts and methods, as collider, instrumental variables, d-separation, backdoor path and, notably, Directed Acyclic Graphs (DAGs). The current theoretical and methodological renewal-or, perhaps, "revolution"-may be changing deeply how clinical and epidemiological research is conceived and performed, how we assess the validity and relevance of findings, and how causal inferences are made. Clinical and basic researchers, among others, should get acquainted with DAGs and related concepts.

Adverse birth outcomes in the vicinity of industrial installations in Spain 2004-2008

Industrial activity is one of the main sources of ambient pollution in developed countries. However, research analyzing its effect on birth outcomes is inconclusive. We analyzed the association between proximity of mother's municipality of residence to industries from 24 different activity groups and risk of very (VPTB) and moderate (MPTB) preterm birth, very (VLBW) and moderate (MLBW) low birth weight, and small for gestational age (SGA) in Spain, 2004-2008. An ecological study was defined, and a "near vs. far" analysis (3.5 km threshold) was carried out using Hierarchical Bayesian models implemented via Integrated Nested Laplace Approximation. VPTB risk was higher for mothers living near pharmaceutical companies. Proximity to galvanization and hazardous waste management industries increased the risk of MPTB. Risk of VLBW was higher for mothers residing near pharmaceutical and non-hazardous or animal waste management industries. For MLBW many associations were found, being notable the proximity to mining, biocides and animal waste management plants. The strongest association for SGA was found with proximity to management animal waste plants. These results highlight the importance of further research on the relationship between proximity to industrial sites and the occurrence of adverse birth outcomes especially for the case of pharmaceutical and animal waste management activities.

Uneven chances of breastfeeding in Spain

BACKGROUND

No large scale studies on breastfeeding onset patterns have been carried out in Spain. This work aims to explore the prevalence and the risk factors for not initiating breastfeeding in hospitals from Catalonia (CAT) and Valencia (V), two regions accounting approximately for 30% of the annual births in Spain.

METHODS

The prevalence of not initiating breastfeeding was calculated by maternal/neonatal characteristics and type of hospital, and logistic regression models were used to estimate crude and adjusted risks of not breastfeeding in each region.

RESULTS

Prevalence of breastfeeding initiation was 81.7% and 82.5% in Catalonia and Valencia, respectively. We identified conspicuous regional differences in the adjusted-risk of not breastfeeding, especially for multiple [CAT = 3.12 (95% CI: 2.93, 3.31), V = 2.44 (95% CI: 2.23, 2.67)] and preterm and low birth weight deliveries [very preterm and very low birth weight: CAT = 7.61 (95% CI: 6.50, 8.92), V = 4.03 (95% CI: 3.13, 5.19); moderate preterm and moderate low birth weight: CAT = 4.28 (95% CI: 4.01, 4.57), V = 2.55 (95% CI:2.34, 2.79)].

CONCLUSIONS

Our results suggest the existence of regional variations in breastfeeding initiation in Spain. Taking into account the known short and long-term benefits of breastfeeding it is recommended that further research should explore these differences in order to prevent potential inequities in neonatal, child and adult health.

The quality of vital statistics for studying perinatal health: the Spanish case

BACKGROUND

Birthweight and gestational age are key indicators for perinatal health obtained through the birth certificate. Knowing the validity of birth certificate data is crucial when identifying needs and evaluating birth outcomes. In Spain, vital information is reported by parents and is not checked for consistency with any hospital document. Therefore, to perform a validation study and describe the variables associated with misreporting is essential to improve the quality of birth certificates.

METHODS

A database was created using birth information from hospital medical records that were individually linked with the Spanish National Institute of Statistics (INE) birth certificate files. Measures of reliability and validity were used to compare the data from the two sources. Logistic regression models were adjusted to model the odds of being misreported in birthweight and gestational age, controlling for relevant variables.

RESULTS

INE overestimated the prevalence of birthweight and gestational age. The degree of agreement between the two sources was good for most gestational age groups (Kappa = 0.74), very good for the very preterm (Kappa = 0.85) and very good also for all categories of birthweight (Kappa = 0.88). Misreporting was significantly higher among immigrants, unmarried mothers and girls. Being a preterm birth increased the odds of being declared with errors in gestational age; having low birthweight and missing information on gestational age were associated with misreporting birthweight.

CONCLUSIONS

The reliability of INE information could be greatly improved if hospitals included birthweight and gestational age on the document provided to parents for registering the birth.

Shortening of gestational length among native-born and immigrants in Spain (1997-2008)

During the last decade there have been significant socio-demographic changes in Spain with potential impact on gestational length. The aim of the study was to describe the evolution of gestational age during 1997-2008, separately for native-born and immigrant population, in order to assess their contribution to the overall pattern of gestational length. A cross-sectional study of 5,018,229 singleton births born between 1997 and 2008 was carried out. The annual mean of gestational age was calculated and compared by means of ANOVA test, globally and also separately for natives and immigrants. Proportions of deliveries by gestational age and maternal characteristics were calculated in 4 periods and compared by means of Chi-square tests. Crude and adjusted multinomial logistic regression models were fitted separately for native-born and immigrant women. Our results show that in the last 12 years a progressive shortening in the mean gestational age has taken place in Spain. While the overall decrease of gestational length along the period was 1.5 days, closer to that in Spanish women (1.3 days), it was 2.3 days among immigrants. In both groups this shortening was mainly due to an increase in the proportion of 37-39 weeks deliveries at the expense of a substantial decrease in those with 40 weeks. These trends remained after controlling for known confounding variables such as maternal age, parity and occupation. Further analysis of its causes and public health implications are recommended.

The epidemiology of HIV and AIDS reports in migrants in the 27 European Union countries, Norway and Iceland: 1999-2006

BACKGROUND

To describe the epidemiology of HIV and AIDS by geographical origin in the EU, 1999-2006.

METHODS

AIDS and HIV cases from the EU 27, Norway and Iceland reported to European Centre for Epidemiological Monitoring of AIDS were analysed.

RESULTS

Of 75,021 AIDS reports over 1999-2006, 35% were migrants. Of 2988 heterosexual AIDS reports in 2006, 50% were migrants, largely from Sub-Saharan Africa (SSA), 20% of 1404 AIDS cases in men who have sex with men (MSM) were migrants from Latin-America and Western Europe. Of 57 mother-to-child transmission (MTCT) AIDS cases, 23% were from SSA. AIDS cases decreased from 1999 to 2006 in natives (42%), Western Europeans (40%) and North Africa and Middle East (34%), but increased in people from SSA (by 89%), Eastern Europe (by 200%) and Latin-America (50%). Of 17,646 HIV infections in men and 9066 in females in 2006, 49 and 76% were migrants, largely from SSA. Of 169 MTCT infections, 41% were from SSA.

CONCLUSION

Migrants, largely from SSA, represent a considerable proportion of AIDS and HIV reports in EU, especially among heterosexual and MTCT infections. Their contribution is higher among female reports. A substantial percentage of diagnoses in MSM are migrants, largely from Western Europe and Latin-America.

[Reproductive and perinatal health indicators in immigrant and Spanish-born women in Catalonia and Valencia (2005-2006)]

OBJECTIVES

To determine the prevalence of teenage maternity, preterm birth and low birth weight in Spanish and immigrant mothers from Latin America, eastern Europe, Maghreb and sub-Saharan Africa resident in Catalonia and Valencia from 2005 and 2006.

METHODS

Using data from congenital metabolic disorders registers in both regions, proportions and 95% confidence intervals were obtained for the following: 1) mothers aged less than 20 years; 2) preterm (<37 weeks) and very preterm (<32 weeks) births; and 3) low birth weight (<2500g) and very low birth weight (<1500g) neonates. The calculations were performed for mothers from each of the geographical areas of origin (Spain, Latin America, Eastern Europe, Maghreb and Sub-Sahara). These proportions were compared in Spanish-born and immigrant women and the significance of differences was assessed using chi-squared tests.

RESULTS

The prevalence of teenage mothers was between three and five times higher in immigrants than in Spanish women, the highest rate being found in women from eastern Europe. Preterm births, very preterm births and very low birth weight were more frequent in eastern European women than in Spanish women. The prevalence of prematurity and very low birth weight was higher in sub-Saharan mothers than in Spanish women.

CONCLUSIONS

The number of births in teenage mothers was higher in immigrant mothers from all origins than in Spanish women. The highest rates of low birth weight and preterm births were found in women from eastern Europe and sub-Saharan Africa.

[Cohort studies and their contribution to the study of HIV infection: main characteristics and limitations]

In this paper, we provide a definition of cohort studies and reviews the main types of cohort studies used in the context of HIV infection. We discuss how the main sources of selection biases in cohort studies are those derived from the lack of observation of the event that determines the origin and/or of the event of interest due to losses to follow-up or development of a competing event, and how this bias must be appropriately taken into account following specific epidemiological methods. Although cohort studies play an essential role in the study of HIV infection, they are logistically complex and require considerable resources. Therefore, strategic planning on the quality and quantity of the information collected must always be accompanied by a resource allocation plan.

Progression of HIV infection and mortality by hepatitis C infection in patients with haemophilia over 20 years

Hepatitis C virus (HCV) infection is an important cause of mortality in human immune deficiency virus (HIV)-positive haemophiliacs. This study describes progression to AIDS, death from HCV end-stage liver disease (ESLD) and all-cause mortality over 20 years. All HIV-positive haemophiliacs in La Paz University Hospital were included in this cohort. HIV seroconversion was estimated using mathematical techniques for interval-censored data from 1979 to 1985. Poisson regression was used to estimate rates of AIDS, death from ESLD and all causes in different periods: before 1988, 1988-89, 1990-91, 1992-93, 1994-95, 1996-97 and 1998-2001 using competing risk models. Among 383 cohort members, global AIDS incidence was 9.7 per 100 person-years, peaking in 1992-93 and dropping by 87% in 1998-2001 compared with before 1988 [incidence rate ratio (IRR) 0.13; 95% CI: 0.03-0.53]. Overall mortality was 7.5 per 100 person-years, was highest from 1992 to 1997, and fell by 66% in 1998-2001 compared with before 1988 (IRR 0.34; 95% CI: 0.14-0.81). Eighteen (5%) persons died of ESLD which represented 19% of deaths before 1988, 4% during 1988-89, 1990-91 and 1992-93, 2% in 1994-95, 10% in 1996-97 and 33% in 1998-2001. Overall death rate from ESLD was 0.5 cases per 100 person-years with no statistically significant trend observed over time. Important reductions in HIV disease progression to AIDS and death have been observed from 1998 to 2001, and can be attributed to highly active antiretroviral therapy. Although no increase in the rate of HCV-related deaths can be demonstrated, HCV accounts for an increasing proportion of deaths in the recent years.

Body mass index and delayed conception: a European Multicenter Study on Infertility and Subfecundity

Obesity has become a health problem in affluent societies, but few studies have investigated its effect on subfertility. Previous studies were based on select groups of women, focused mainly on ovulatory dysfunctions, and yielded controversial results. The authors evaluated the effect of body mass index on delayed conception by using a European population-based survey of pregnant women from five countries. Delayed conception was defined as a time to pregnancy that exceeded 9.5 months of unprotected intercourse. During 1992, 4,035 pregnant women from well-defined geographic areas were recruited consecutively at antenatal clinics or hospitals after at least 20 weeks of gestation. For women smokers, after adjustment for sociodemographic, biologic, and lifestyle-related factors, there was a strong association between obesity (body mass index of > or =30 kg/m2) and delayed conception (odds ratio = 11.54, 95% confidence interval: 3.68, 36.15) and also an increased risk for women whose body mass index was <20 kg/m2 (odds ratio = 1.70; 95% confidence interval: 1.01, 2.83). The same analysis conducted for women nonsmokers showed no association. The authors concluded that for women who achieve a clinically detectable pregnancy, those who are underweight or obese require a longer time to conceive only if they also smoke.

Variations in cotinine levels in smokers during and after pregnancy

OBJECTIVE

To compare the antenatal and postnatal cotinine levels in smoking women after controlling for the differences in smoking practices.

STUDY DESIGN

A paired comparison of two measurements of cotinine concentration was conducted in 40 smoking women voluntarily recruited in a prenatal education program held in La Fe Hospital, Valencia, Spain, during 1990 and 1991. Cotinine concentration was assayed by gas chromatography in samples of saliva obtained during and after pregnancy. The Wilcoxon matched-pairs test and multiple linear regression analysis were used.

RESULTS

The cotinine per cigarette ratio during pregnancy (median 3.53 ng/ml per cigarette) was significantly lower than the ratio in the postnatal testing (median 9.87 ng/ml per cigarette). This difference persisted after allowing for differences in reported cigarette consumption.

CONCLUSION

These findings suggest that the available equivalencies between cotinine level and nicotine intake obtained from adult nonpregnant populations cannot be directly applied during pregnancy.

Caffeine intake and delayed conception: a European multicenter study on infertility and subfecundity. European Study Group on Infertility Subfecundity

The effects of caffeine consumption on delayed conception were evaluated in a European multicenter study on risk factors of infertility. Information was collected retrospectively on time of unprotected intercourse for the first pregnancy and the most recent waiting time episode in a randomly selected sample of 3,187 women aged 25-44 years from five European countries (Denmark, Germany, Italy, Poland, and Spain) between August 1991 and February 1993. The consumption of caffeinated beverages at the beginning of the waiting time was used to estimate daily caffeine intake, which was categorized as 0-100, 101-300, 301-500, and > or = 501 mg. Risk of subfecundity (> or = 9.5 months) and the fecundability ratio, respectively, were assessed by logistic regression and Cox proportional hazard analyses, adjusting for age, parity, smoking, alcohol consumption, frequency of intercourse, educational level, working status, use of oral contraceptives, and country. A significantly increased odds ratio (OR) of 1.45 (95% confidence interval (CI) 1.03-2.04) for subfecundity in the first pregnancy was observed for women drinking more than 500 mg of caffeine per day, the effect being relatively stronger in smokers (OR = 1.56, 95% CI 0.92-2.63) than in nonsmokers (OR = 1.38, 95% CI 0.85-2.23). Women in the highest level of consumption had an increase in the time leading to the first pregnancy of 11% (hazard ratio = 0.90, 95% CI 0.78-1.03). These associations were observed consistently in all countries as well as for the most recent waiting time episode. The authors conclude that high levels of caffeine intake may delay conception among fertile women.

[Income, percent of women living in rural areas, parity, and breast cancer mortality in Spain, 1975-1991]

BACKGROUND

The aim of the present study was to analyze breast cancer mortality by provinces in Spain during the period 1975-91, and to assess the relationship with the geographical distribution of income level, percent of women living in rural areas and average parity of women in each province.

SUBJECTS AND METHODS

Data were obtained from national statistical sources. Standardized mortality ratios (SMR) for breast cancer were estimated by provinces for the periods 1975-1980, 1981-1986 and 1987-1991, and for the whole period 1975-1991. Poisson regression analysis was used to explore the association between breast cancer mortality and the above mentioned variables. Provinces were categorized according to the quintile distribution of independent variables, and ecological relative risks were estimated for each category.

RESULTS

Higher SMR were observed in island provinces (Canary and Balearic island), Catalonia, Basque Country, Navarre and the provinces of Saragosa, Seville and Valencia. Lowest SMR were observed in the inner provinces of Spain and the east part of Andalusian region. This pattern has remained very similar along the study period: income level showed a positive association with mortality from breast cancer. On the contrary, percent of women living in rural areas and parity were negatively associated to breast cancer mortality. The relative risk estimated for each child of parity adjusted by the other factors was 0.92 (95% confidence interval: 0.89-0.94).

CONCLUSIONS

The highest mortality from breast cancer in Spain has been observed in those provinces with the highest income level, the lowest percent of women living in rural areas and the lowest parity. These findings at the ecological (provinces) level are in concordance with results from other studies at the individual level, and further supports the hypothesis that for the etiology of breast cancer, environmental factors could play a dominant role.

Trends in incidence and prevalence of HIV-1 infection in intravenous drug users in Valencia, Spain

Our objective was to describe and compare the trends of incidence and prevalence of HIV-1 infection in intravenous drug users (IDUs) in Valencia, Spain in 1987-1992. A cohort study was carried out in AIDS Information Centers located in the Valencia Region (Spain). Point seroprevalence was calculated for in each year according to HIV status at the first contact. Incidence annual rates were calculated from those IDUs identified as seronegative in their first visit and who returned for a new testing. From a total of 4,207 IDUs who contacted these centers, 4,131 (98.2%) asked voluntarily for HIV-1 testing. The seroprevalence for the whole period was 48.4% (95% C.I., 46.88, 49.92). Follow-up information was available for 604 subjects of the total 2,130 subjects who were seronegative in their first visit. The incidence rate for the 1988-1992 period was 12.02/100 person-years (95% C.I., 9.62, 14.41). Prevalence showed an overall decreasing pattern with a minimum corresponding to the year 1992 (43.6%). Incidence rates increased mildly until 1990 (13.93 per 100 person-years), to stabilize beyond at approximately 10 per 100 person-years. Our incidence rates are very high regardless of the decline of prevalence. Effective risk reduction programs among IDUs have been almost nonexistent in Spain up to now and should become an immediate priority.