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Biomedical subjects

J M Belizán

Publications and source records attributed to J M Belizán.

At least 19 recordsLinked to original sources

Effect of the interpregnancy interval after an abortion on maternal and perinatal health in Latin America.

OBJECTIVE: To investigate whether the length of the interval between an abortion and the next pregnancy is associated with increased risks of adverse maternal and perinatal outcomes in Latin America. METHOD: Retrospective cross-sectional study using information from 258,108 women delivering singleton infants and whose previous pregnancy resulted in abortion recorded in the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay, between 1985 and 2002. Adjusted odds ratios were obtained through logistic regression analysis. RESULT: Compared with the post-abortion interpregnancy intervals of 18 to 23 months, intervals shorter than 6 months were significantly associated with increased risks of maternal anemia, premature rupture of membranes, low birth weight, very low birth weight, preterm delivery, and very preterm delivery. CONCLUSION: In Latin America, post-abortion interpregnancy intervals shorter than 6 months are independently associated with increased risks of adverse maternal and perinatal outcomes in the next pregnancy. DEFINITION: Post-abortion interpregnancy interval (PAII): the time elapsed between the day of the abortion and the first day of the last menstrual period for the index pregnancy.

Abortion, Induced↗

The epidemiology of syphilis in pregnancy.

This study evaluated the magnitude, risk factors and outcomes of syphilis in pregnancy in a large cohort of women in four countries participating in the World Health Organization (WHO) antenatal care trial. All women attending the first prenatal care at each selected clinic were enrolled. Screening at the first antenatal visit was routinely performed with either rapid plasma reagin or Venereal Disease Research Laboratory and confirmed by fluorescent treponemal antibody absorption. All women also had the same syphilis tests after delivery. The initial prevalence, the incidence during pregnancy and the overall prevalence of syphilis at delivery were 0.9%, 0.4% and 1.3% respectively. Risk factors for syphilis during pregnancy were younger age for the incidence and older age and a history of stillbirth for the prevalence. Women with syphilis during pregnancy had significantly more adverse outcomes. We support the recommendation that in addition to the initial testing, a second routine test for syphilis ought to be established early in the third trimester even in low prevalence areas.

Adult↗

[Sleeping position to prevent sudden infant death syndrome in Latin-american and Caribbean hospitals].

Background The prone sleeping position for sleeping has been identified as the principal risk factor for sudden infant death syndrome (SIDS).ObjectiveThe aim of this study was to determine the prevalence of different sleeping positions and other risk factors for SIDS and to identify the advice given to parents in several maternity units in Latin America and the Caribbean through a specially-designed questionnaire.MethodsDescriptive cross-sectional study based in hospitals. All the countries in Latin America and the Caribbean were contacted through the Pan American Health Organization and responses were obtained from 16 countries.ResultsTwo hundred thirteen hospitals answered the survey. The preferred sleeping position for healthy infants was prone in 8.5 % of the hospitals, side in 48.8 %, and supine in 25.2 %. In 17.5 % of the hospitals no position was preferred or the answers were inconsistent.Concerning the recommendations given to parents on the best position for their infants at home, 25.7 % recommended the supine position, 7.6 % the prone position, 59.0 % the side position while 7.6 % made no recommendations.ConclusionsThe results of this study show that in the hospitals surveyed there is a policy of not placing healthy neonates in the prone position. However, the most frequent position was the side, which is not advisable as it increases the risk of SIDS. To reduce in the incidence of SIDS, campaigns to increase the use of the supine position should be carried out in hospitals and among the general public.

Caribbean Region↗

Methodological considerations on the design and analysis of an equivalence stratified cluster randomization trial.

The World Health Organization and collaborating institutions in four developing countries have conducted a multi-centre randomized controlled trial, in which clinics were allocated at random to two antenatal care (ANC) models. These were the standard 'Western' ANC model and a 'new' ANC model consisting of tests, clinical procedures and follow-up actions scientifically demonstrated to be effective in improving maternal and newborn outcomes. The two models were compared using the equivalence approach. This paper discusses the implications of the equivalence approach in the sample size calculation, analysis and interpretation of results of this cluster randomized trial. It reviews the ethical aspects regarding informed consent, concluding that the Zelen design has a place in cluster randomization trials. It describes the estimation of the intracluster correlation coefficient (ICC) in a stratified cluster randomized trial using two methods and reports estimates of the ICC obtained for many maternal, newborn and perinatal outcomes. Finally, it discusses analytical problems that arose: issues encountered using a composite index, heterogeneity of the intervention effect across sites, the choice of the method of analysis and the importance of efficacy analyses. The choice of the clustered Woolf estimator and the generalized estimating equations (GEE) as the methods of analysis applied is discussed.

Adult↗

Maternal morbidity and mortality associated with interpregnancy interval: cross sectional study.

OBJECTIVE: To study the impact of interpregnancy interval on maternal morbidity and mortality. DESIGN: Retrospective cross sectional study with data from the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay. SETTING: Latin America and the Caribbean, 1985-97. PARTICIPANTS: 456 889 parous women delivering singleton infants. MAIN OUTCOME MEASURES: Crude and adjusted odds ratios of the effects of short and long interpregnancy intervals on maternal death, pre-eclampsia, eclampsia, gestational diabetes mellitus, third trimester bleeding, premature rupture of membranes, postpartum haemorrhage, puerperal endometritis, and anaemia. RESULTS: Short (<6 months) and long (>59 months) interpregnancy intervals were observed for 2.8% and 19.5% of women, respectively. After adjustment for major confounding factors, compared with those conceiving at 18 to 23 months after a previous birth, women with interpregnancy intervals of 5 months or less had higher risks for maternal death (odds ratio 2.54; 95% confidence interval 1.22 to 5.38), third trimester bleeding (1.73; 1.42 to 2.24), premature rupture of membranes (1.72; 1.53 to 1.93), puerperal endometritis (1.33; 1.22 to 1.45), and anaemia (1.30; 1.18 to 1.43). Compared with women with interpregnancy intervals of 18 to 23 months, women with interpregnancy intervals longer than 59 months had significantly increased risks of pre-eclampsia (1.83; 1.72 to 1.94) and eclampsia (1.80; 1.38 to 2.32). CONCLUSIONS: Interpregnancy intervals less than 6 months and longer than 59 months are associated with an increased risk of adverse maternal outcomes.

Abortion, Spontaneous↗

Risk factors for pre-eclampsia in a large cohort of Latin American and Caribbean women.

OBJECTIVE: To study risk factors for pre-eclampsia in a large cohort of Latin American and Caribbean women. DESIGN: Retrospective cross-sectional study from the Perinatal Information System, the database of the Latin American Center for Perinatology and Human Development, Montevideo, Uruguay. SETTING: Latin America and the Caribbean, 1985-1997. Population 878,680 pregnancies at 700 hospitals; of these 42,530 were complicated by pre-eclampsia and 1,872 by eclampsia. MAIN OUTCOME MEASURES: Crude and adjusted relative risks (RR) of risk factors for pre-eclampsia. Adjusted relative risks were obtained after adjustment for potential confounding factors through multiple logistic regression models based on the method of generalised estimating equations. RESULTS: The following risk factors were significantly associated with increased risk of pre-eclampsia: nulliparity (RR 2 x 38; 95% CI 2 x 28-2 x 49); multiple pregnancy (RR 2 x 10; 95% CI 1 x 90-2 x 32); history of chronic hypertension (RR 1 x 99; 95% CI 1 x 78-2 x 22); gestational diabetes mellitus (RR 1 x 93; 95% CI 1 x 66-2 x 25); maternal age > or = 35 years (RR 1 x 67; 95% CI 1 x 58-1 x 77); fetal malformation (RR 1 x 26; 95% CI 1 x 16-1 x 37); and mother not living with infant's father (RR 1 x 21; 95% CI 1 x 15-1 x 26). Pre-eclampsia risk increased according to pre-pregnancy body mass index (BMI). In comparison with women with a normal pre-pregnancy BMI (19 x 8 to 26 x 0), the RR estimates were 1 x 57 (95% CI 1 x 49-1 x 64) and 2 x 81 95% CI 2 x 69-2 x 94), respectively, for overweight women (pre-pregnancy BMI = 26 x 1 to 29 x 0) and obese women (pre-pregnancy BMI > 29 x 0). Cigarette smoking during pregnancy and a pre-pregnancy BMI < 19 x 8 were significant protective factors against the development of pre-eclampsia. The pattern of risk factors among nulliparous and multiparous women was quite similar. CONCLUSIONS: Risk factors for pre-eclampsia observed among Latin American and Caribbean women are similar to those found among North American and European women.

Adolescent↗

Same nutrient, different hypotheses: disparities in trials of calcium supplementation during pregnancy.

Calcium supplementation during pregnancy has been provided either to increase the intake in those with a deficiency or to obtain a pharmacologic, perhaps nonnutritional, effect in individuals with an adequate calcium intake. A systematic review, including only randomized, double-blind, controlled trials of calcium supplementation during pregnancy was prepared independently for the Cochrane Library and updated by us for this paper. In view of the heterogeneity of results included in the meta-analysis, a stratified analysis by baseline dietary calcium intake (mean calcium intake in the population < or >/=900 mg/d) was conducted. On the basis of the results of the 5 randomized, controlled trials available, the risk of high blood pressure was lower in women with low baseline dietary calcium [typical relative risk (TRR): 0.49; 95% CI: 0.38, 0.62]. Of the 4 trials in which subjects had adequate dietary calcium, the TRR of high blood pressure was 0.90 (95% CI: 0.81, 0.99). The risk of preeclampsia was considerably reduced in the 6 trials conducted in populations with low-calcium diets (TRR: 0.32; 95% CI: 0.21, 0.49) but was not reduced as much in women enrolled in the 4 trials with adequate-calcium diets (TRR: 0.86; 95% CI: 0.71, 1.05). On the basis of these results, it seems clear that calcium supplementation during pregnancy for women with deficient calcium intake is a promising preventive strategy for preeclampsia. Calcium supplementation in pregnancy should be evaluated definitively in an adequately sized trial conducted in a population with a low calcium intake because this is the most likely population to benefit from such a nutritional intervention. Long-term health benefits for the offspring are also an attractive possibility.

Calcium, Dietary↗

Epidemiology of fetal death in Latin America.

BACKGROUND: To identify risk factors associated with fetal death, and to measure the rate and the risk of fetal death in a large cohort of Latin American women. METHODS: We analyzed 837,232 singleton births recorded in the Perinatal Information System Database of the Latin American Center for Perinatology and Human Development (CLAP) between 1985 and 1997. The risk factors analyzed included fetal factors and maternal sociodemographic, obstetric, and clinical characteristics. Adjusted relative risks were obtained, after adjustment for potential confounding factors, through multiple logistic regression models based on the method of generalized estimating equations. RESULTS: There were 14,713 fetal deaths (rate=17.6 per 1000 births). The fetal death risk increased exponentially as pregnancy advanced. Thirty-seven percent of all fetal deaths occurred at term, and 64% were antepartum. The main risk factors associated with fetal death were lack of antenatal care (adjusted relative risk [aRR]=4.26; 95% confidence interval, 3.84-4.71) and small for gestational age (aRR=3.26; 95% CI, 3.13-3.40). In addition, the risk of death during the intrapartum period was almost tenfold higher for fetuses in noncephalic presentations. Other risk factors associated with stillbirth were: third trimester bleeding, eclampsia, chronic hypertension, preeclampsia, syphilis, gestational diabetes mellitus, Rh isoimmunization, interpregnancy interval<6 months, parity > or =4, maternal age > or =35 years, illiteracy, premature rupture of membranes, body mass index > or =29.0, maternal anemia, previous abortion, and previous adverse perinatal outcomes. CONCLUSIONS: There are several preventable factors that should be dealt with in order to reduce the gap in fetal mortality between Latin America and developed countries.

Adolescent↗

Maternal morbidity and mortality associated with multiple gestations.

OBJECTIVE: To test the hypothesis that women with multiple gestations are at increased risk of adverse maternal outcomes. METHODS: We studied the association between multiple gestation and frequency of adverse maternal outcomes in 885,338 pregnancies recorded in the Perinatal Information System database of the Latin American Center for Perinatology and Human Development, Montevideo, Uruguay, between 1985 and 1997. Relative risks (RRs) were adjusted for 14 potential confounding factors through multiple logistic regression models. RESULTS: There were 15,484 multiple gestations. Among parous women, multiple gestation was associated with a twofold increase in risk of death compared with singleton gestations [adjusted RR 2.1; 95% confidence interval (CI) 1.1, 3.9]. Compared with singleton gestations, women with multiple gestations had adjusted RRs of 3.0 (95% CI, 2.9, 3.3) for eclampsia, 2.2 (95% CI, 1. 9, 2.5) for preeclampsia, and 2.0 (95% CI, 1.9, 2.0) for postpartum hemorrhage. Likewise, there was significant association between multiple gestation and increased incidence of preterm labor, anemia, urinary tract infection, puerperal endometritis, and cesarean delivery. The incidences of premature rupture of membranes, third-trimester bleeding, and gestational diabetes mellitus were not statistically different for singleton and multiple gestations. CONCLUSION: Multiple gestation increases the risk of significant maternal morbidity and mortality.

Adult↗

Rates and implications of caesarean sections in Latin America: ecological study.

OBJECTIVES: To estimate the incidences of caesarean sections in Latin American countries and correlate these with socioeconomic, demographic, and healthcare variables. DESIGN: Descriptive and ecological study. SETTING: 19 Latin American countries. MAIN OUTCOME MEASURES: National estimates of caesarean section rates in each country. RESULTS: Seven countries had caesarean section rates below 15%. The remaining 12 countries had rates above 15% (range 16.8% to 40.0%). These 12 countries account for 81% of the deliveries in the region. A positive and significant correlation was observed between the gross national product per capita and rate of caesarean section (r(s)=0.746), and higher rates were observed in private hospitals than in public ones. Taking 15% as a medically justified accepted rate, over 850 000 unnecessary caesarean sections are performed each year in the region. CONCLUSIONS: The reported figures represent an unnecessary increased risk for young women and their babies. From the economic perspective, this is a burden to health systems that work with limited budgets.

Cesarean Section↗

Cigarette smoking during pregnancy and risk of preeclampsia: a systematic review.

In this systematic review of the existing evidence regarding the relationship between cigarette smoking during pregnancy and preeclampsia, studies were found through searches of MEDLINE (1966-October 31, 1998), Embase, Popline, CINAHL, Lilacs, bibliographies of identified studies, and proceedings of meetings on preeclampsia, and also through contact with relevant researchers. No language restrictions were imposed. Only cohort and case-control studies dealing with the relationship between cigarette smoking and preeclampsia were considered. Assessment of methodologic quality and data extraction of each study were carried out by 2 authors working independently. Typical relative risks and odds ratios with 95% confidence intervals were calculated for cohort and case-control studies, respectively, with both fixed and random effects models. Twenty-eight cohort studies and 7 case-control studies including a total of 833,714 women were included. All cohort studies reported an inverse association between cigarette smoking during pregnancy and incidence of preeclampsia (typical relative risk, 0.68; 95% confidence interval, 0.67-0.69). The findings were similar for case-control studies (typical odds ratio, 0.68; 95% confidence interval, 0.57-0.81). An inverse dose-response relationship was also found. Pooled data from cohort and case-control studies showed a lower risk of preeclampsia associated with cigarette smoking during pregnancy.

Case-Control Studies↗

[Preterm delivery: detection of risks and preventive treatment].

Every year around the world some 13 million premature children are born. Most of these children are born in developing countries, and they account for the largest share of perinatal morbidity and mortality. This review study analyzed scientifically validated data on interventions to prevent at least some portion of these preterm deliveries and to lessen their impact on neonatal health. The Cochrane and MEDLINE bibliographic databases were consulted. Fifty review pieces and research articles were studied, relating to the following aspects of preterm delivery: risk factors and early detection of the risk of preterm delivery; preventing the risk of preterm delivery; treating preterm delivery once it has begun; and preventing neonatal respiratory distress syndrome. There were few successful approaches to the prediction, prevention, or early detection of the threat of preterm delivery. The only measures that can be recommended for all pregnant women are screening for and treating asymptomatic bacteriuria as a part of prenatal check-ups. Screening for bacterial vaginosis and treating it reduce the incidence of preterm births in pregnant women with a history of premature delivery. In addition, prophylactic cerclage decreases the incidence of premature births in pregnant women who have had more than three preterm births. To treat a delivery that starts early, with or without premature membrane rupture, the interventions that have proved to be effective are administering betamimetics to the parturient woman in order to delay delivery for 48 hours, and using indomethacin for the same purpose, as the second-choice drug. The prenatal administration of corticosteroids to the pregnant woman can induce lung maturation in the fetus and reduce respiratory distress syndrome and ventricular hemorrhage, thus decreasing neonatal mortality. There is a need to continue and support basic and epidemiological research in order to develop new knowledge on the causes and mechanisms of preterm delivery and on preventing the morbidity and mortality that preterm delivery produces.

Female↗

The WHO antenatal care randomised controlled trial: rationale and study design.

The World Health Organisation and collaborating institutions in developing countries are conducting a multicentre randomised controlled trial to evaluate a new antenatal care (ANC) programme, consisting of tests, clinical procedures and follow-up actions scientifically demonstrated to be effective in improving maternal and newborn outcomes. These activities are distributed, for practical reasons, over four visits during the course of pregnancy and are aimed at achieving predetermined goals. The study is taking place in four countries, Argentina, Cuba, Saudi Arabia and Thailand. Recruitment of study subjects started on 1 May 1996. All 53 ANC clinical units had been enrolled by December 1996. Clinics in each country were randomly allocated (cluster randomisation) to provide either the new programme or the traditional programme currently in use. Approximately 24,000 women presenting for ANC at these clinics over an average period of 18 months will have been recruited. As women attending the control clinics receive the 'best standard treatment' as currently offered in these clinics, individual informed consent is requested only from women attending the intervention clinics. Authorities of the corresponding health districts and all participating clinics have provided written institutional informed consent before randomisation. The primary outcome of the trial in relation to maternal conditions is the rate of a morbidity indicator index, defined as the presence of at least one of the following conditions for which ANC is relevant: (a) pre-eclampsia or eclampsia during pregnancy or within 24 h of delivery; (b) postpartum anaemia (haemoglobin < 90 g/L); or (c) severe urinary tract infection/pyelonephritis, defined as an episode requiring antibiotic treatment and/or hospitalisation. The primary fetal outcome is the rate of low birthweight (< 2500 g). Adverse maternal and fetal outcomes are expected for approximately 10% of the control group. Several maternal and perinatal secondary outcomes are also considered. A comprehensive cost-effectiveness analysis and women's and providers' satisfaction evaluation are performed concurrently with the trial. Health-care programmes should be rigorously evaluated by randomised controlled trials, which are feasible in developing countries and should be conducted before introducing new treatments or health interventions.

Argentina↗

Methodological considerations in the design of the WHO Antenatal Care Randomised Controlled Trial.

We discuss methodological issues arising in a recent evaluation trial of a new antenatal care programme, as sponsored by the Special Programme of Research, Development and Research Training in Human Reproduction, and WHO's Division of Reproductive Health (Technical Support). The randomisation unit for the trial is the antenatal care clinic, with 53 clinics located in four countries randomly allocated to provide either the new programme or the traditional programme currently in use. Approximately 24,000 women presenting for antenatal care over an average period of 18 months will have been recruited.

Argentina↗