Original Article
A Randomized Trial of Psychosocial Support during High-Risk Pregnancies
N Engl J Med 1992; 327:1266-1271October 29, 1992
- Abstract
- Abstract
Background.
It is often suggested that psychological and social support and health education for women at high risk for delivering a low-birth-weight infant can improve the outcomes of pregnancy, but the evidence is inconclusive. We undertook this prospective trial to evaluate a program of home visits designed to provide psychosocial support during pregnancy.
Methods.
At four centers in Latin America, 2235 women at higher-than-average risk for delivering a low-birth-weight infant were recruited before the 20th week of pregnancy. The women were randomly assigned either to an intervention group (n = 1115) that received four to six home visits from a nurse or social worker in addition to routine prenatal care or to a control group (n = 1120) that received only routine prenatal care (with a mean of eight prenatal visits). The principal measures of outcome were low birth weight (<2500 g), preterm delivery (<37 weeks of gestation), and specified categories of maternal and neonatal morbidity.
Results.
The women who received the home visits as well as routine prenatal care had outcomes that differed little from those of the women who received only routine care. The risks of low birth weight (odds ratio for the intervention group as compared with the control group, 0.93; 95 percent confidence interval, 0.68 to 1.28), preterm delivery (odds ratio, 0.88; 95 percent confidence interval, 0.67 to 1.16), and intrauterine growth retardation (odds ratio, 1.08; 95 percent confidence interval, 0.83 to 1.40) were similar in the two groups. There was no evidence that the intervention had any significant effect on the type of delivery, the length of hospital stay, perinatal mortality, or neonatal morbidity in the first 40 days. There was no protective effect of the psychosocial-support program even among the mothers at highest risk.
Conclusions.
Interventions designed to provide psychosocial support and health education during high-risk pregnancies are unlikely to improve maternal health or to reduce the incidence of low birth weight among infants. (N Engl J Med 1992;327:1266–71.)
Media in This Article
Table 1
Distribution of Risk Factors at Entry, According to Treatment Group.*Table 2
Base-Line Characteristics of the Women, According to Treatment Group.*Article Activity
- Article
PRETERM delivery and intrauterine growth retardation remain major health problems in both developing and developed societies.1 , 2 Although several epidemiologic studies in Latin America3 , 4 and elsewhere5 have consistently identified risk factors associated with low birth weight, programs aimed at controlling or preventing these risk factors have had only limited effects,6 , 7 unless intensive and long-term interventions were undertaken8 or the target populations were extremely underprivileged.9
Most of the interventions that have been formally tested in randomized controlled trials have been medically oriented, and it has been suggested that too little consideration has been given to pregnant women's psychological and social well-being. These aspects of maternal health could be as important as biologic factors, it has been argued, particularly among women living in poverty who are at high risk for poor outcomes of pregnancy. Psychological stress and lack of social support, together with the adverse effects of high-risk medical conditions, could interact with an unhealthy lifestyle and a reduced access to adequate health care,10 , 11 thereby adversely affecting the outcome of pregnancy.
In a large, randomized multicenter trial, we compared the outcomes of pregnancy among women at high risk who received standard prenatal care with those among women whose prenatal care was supplemented with four to six home visits designed to provide psychosocial support and health education.
Methods
The trial was conducted from January 1989 through March 1991 under the auspices of the Latin American Network for Perinatal and Reproductive Research11 12 13 in its centers in the cities of Rosario, Argentina; Pelotas, Brazil; Havana, Cuba; and Mexico City. The research protocol was approved by the human studies committees of the four institutions.
Subjects
The principal criteria for entry into the trial were the presence of one or more of the following risk factors for delivering a low-birth-weight infant: previous delivery of a low-birth-weight or preterm infant; previous fetal or infant death; age <18 years; body weight ≤50 kg, height ≤1.5 m; low family income defined according to locally adapted cutoff points; less than three years of school; smoking or heavy alcohol consumption; and residence apart from the child's father.
Women who met these criteria were recruited if they started prenatal care during weeks 15 to 22 of a singleton pregnancy and had no history of major mental illness, cervical cerclage, or Rh isoimmunization. Randomization was carried out by the Data Coordinating Center in Pelotas; a computer-generated code was used for randomization within balanced blocks of 20 women, stratified according to center. Formal entry into the trial was delayed until a base-line interview had been completed and the woman had given informed consent. A sequence of sealed, opaque envelopes was used by a single investigator in each hospital to assign the women to treatment groups, and a particular woman's group assignment was known only to this investigator, the study supervisor, and the home visitor.
Treatment
The intervention was aimed primarily at increasing social support and reducing stress and anxiety. Four home visits were made during or near weeks 22, 26, 30, and 34 of gestation, with the option for two more visits at the discretion of the woman and the study staff.
Specially trained female social workers in Argentina, Brazil, and Mexico and obstetrical nurses in Cuba carried out the home visits. Before the study, training was provided in 26 sessions of four hours each; it included theoretical and practical instructions and the use of role playing that focused on how to conduct the visits and respond to possible personal or social situations. The home visitors were paid a full-time salary equivalent to that received by social workers or nurses in the public health sector.
Schedules for the visits were set in advance with the patient and her family or designated "support person." Each visit was planned to last between one and two hours; the home visitor used a standard manual in conducting the visits. The manual and the proposed activities for the visits were based on information from ethnographic studies conducted in each site before the initiation of the trial. The manual included detailed descriptions of various situations that home visitors were likely to encounter, with suggested interventions. It was intended that home visitors at the different study sites would act in a similar way, with adaptations appropriate to the local culture.
The main objective of the visits was the strengthening of the pregnant woman's social network. A support person (husband or partner, mother, sister, friend, or neighbor) was selected by the patient to share all intervention activities beginning with the first visit. The support person was strongly encouraged to remain involved with the woman throughout the pregnancy, to participate in the decision-making process, to help the woman resolve personal problems, to promote healthful behavior, and to encourage attendance at visits for prenatal care. The home visitor provided direct emotional support to the woman and helped her to cope with problems related to medical recommendations or prenatal care.
The first part of each visit was devoted to encouraging the pregnant woman and her support person to discuss the pregnancy, especially any changes, worries, or doubts. Using this information as background, the home visitor adapted the themes defined in the study protocol, focusing the discussion on information relevant to each woman. The home visitor discussed her proposed strategy with the study supervisor after the first visit and designed an individual plan for each woman. Changes were made, if necessary, during subsequent visits.
To complement the provision of psychosocial support during the home visits, a special support office for women in the intervention group was established in each hospital. Women could visit without prior appointments or call on a telephone line reserved for such calls. The office was intended to help women with problems related to attendance at prenatal care appointments and compliance with treatment or laboratory tests, and to monitor adherence to doctors' recommendations. Women close to term had a guided tour of the hospital that focused on the labor and delivery unit and the emergency room.
Finally, health education was provided during the home visit; this included education about nutrition and suggestions about reducing smoking and alcohol or drug use. A carefully designed poster and booklet were given to each woman during the first home visit. Using familiar terms and situations, these materials gave advice and encouraged healthful behavior and good nutrition. No attempt was made to provide medical care during the home visits.
The control group was provided with the routine prenatal care available at each of the participating institutions. Physicians and nurses in the prenatal clinics were not selected for the study, and the women were assigned for care according to the standard hospital procedures. The clinic personnel were never told whether women were in the trial, although some may have identified themselves as participants.
Evaluation of the Intervention
To evaluate whether the planned material was covered during the home visits, a precoded form was completed by the home visitor at the end of each visit and reviewed by the project coordinator. Five percent of all home visits, selected randomly, were observed by the project coordinator, without previous notification, and a second set of forms identical to those used by the home visitor was independently completed by the project coordinator. Similarly, a 5 percent random sample of the postpartum questionnaires was also independently repeated. Results of comparisons between the two sets of data were used to identify social workers and interviewers to undergo retraining.
Data for the evaluation of procedures and treatment effects were collected by a team of independent professional interviewers who were not informed about the nature of the study. The interviews were carried out for the intervention and control groups at home during the 36th week of gestation, in the hospital immediately after delivery, and 40 days post partum at home. At the 36-week interview, information was obtained on social support, knowledge about pregnancy and delivery and health-related behavior, as well as levels of psychological distress. After delivery, data were collected from medical records on prenatal care, labor and delivery, and the health status of the newborn. During the 40-day postpartum visit information was collected on maternal and infant morbidity and feeding practices.
Base-line information on several indicators of psychological distress and social support was used to construct two summary variables. The psychological-distress variable was a weighted normalized score, including the results of the Spielberger anxiety test,14 reported feelings toward the pregnancy, expectations about delivery, and fears about being a bad mother. The social-support variable was obtained from a factor analysis, including information on whether the father was present, his attitude, and any help he provided, support provided at home by others, and the woman's degree of satisfaction with this help. Women were classified as having a low level of distress or social support if their scores were at or below the median value for these variables in the total study sample, and as having a high level of distress or social support if their scores were above the corresponding median.
Statistical Analysis
It was calculated before the study began that a sample size of 1200 women in each group would provide 90 percent power (α = 0.05) of identifying a reduction in the frequency of low birth weight, from 20 percent in the control group to 15 percent in the intervention group, allowing for attrition of 20 percent. However, the actual rate of low birth weight in the control group was 9.4 percent. The actual sample size of 2235 gave the study 80 percent power (α = 0.05) of detecting a reduction from this rate to 6 percent in the intervention group. The data were analyzed on an intention-to-treat basis according to the group to which the women were randomly assigned.
We compared the two groups using the chi-square test or z-test. Crude analyses and analyses adjusted for potential confounding variables were carried out when appropriate. Logistic regression was used to calculate odds ratios and 95 percent confidence intervals for dichotomous outcome variables, and linear regression for estimating differences in continuous outcome variables.
Stratified analyses were conducted to compare the results among previously designated subgroups in the intervention and control groups, specifically women with high levels of psychological distress and low levels of social support at base line, those who smoked, nulliparous women, women with a history of adverse pregnancy outcome, and those less than 18 years of age.
This report focuses on the effect of the intervention on the incidence of low birth weight (<2500 g), preterm delivery (<37 weeks), intrauterine growth retardation (<10th percentile for a reference population15), intrapartum interventions, and neonatal morbidity and mortality. We have not included any effects of the intervention on the women's psychological well-being in this report.
Results
A total of 5990 women were screened for the risk factors required for trial entry, and 2235 (37 percent) were considered eligible and agreed to participate in the study. Of these women, 1115 were randomly assigned to the intervention group and 1120 to the control group.
The distribution of risk factors at entry was similar in the two groups (Table 1Table 1
Distribution of Risk Factors at Entry, According to Treatment Group.*). The mean (±SD) gestational age at randomization was 18.3±2.3 weeks for both groups. Overall, the two groups had similar demographic, obstetrical, and psychological characteristics at base line (Table 2Table 2Base-Line Characteristics of the Women, According to Treatment Group.*). Despite the good overall comparability of the intervention and control groups, there were differences in some variables when the two groups were considered on a country-by-country basis. Those variables and country of residence were treated as potential confounding variables in the adjusted analyses.Most (83 percent) of the women randomly assigned to the intervention group received the planned number of home visits, and 90 percent were visited at least once. The various planned components of the home visit, including health education, discussions of specific topics, and encouragement of the use of health services, were included in more than 80 percent of the visits. The support person was present at 66 percent of the first visits, 57 percent of the second visits, 51 percent of the third visits, and 52 percent of the fourth visits. The groups had similar numbers of visits to the medical center for prenatal care (8.1 ±3.7 in the control group vs. 8.0±3.8 in the intervention group). By the 37th week of gestation, the women in the intervention group had significantly greater knowledge of the signs and symptoms of pregnancy complications and more favorable expectations about delivery. The proportion of smokers in the intervention group declined from 24 percent at entry to 19 percent at 37 weeks. The comparable proportions were 22 percent and 20 percent, respectively, in the control group.
Low Birth Weight, Preterm Delivery, and Intrauterine Growth Retardation
No differences were observed between the groups in any of the principal measures of outcome (Table 3Table 3
Effect of Psychosocial Support during Pregnancy on Primary Outcome Measures.). The rate of low birth weight was 8.7 percent in the intervention group and 9.4 percent in the control group (odds ratio, 0.93; 95 percent confidence interval, 0.68 to 1.28), and the rate of preterm delivery was 11.1 percent and 12.5 percent (odds ratio, 0.88; 95 percent confidence interval, 0.67 to 1.16). The rate of intrauterine growth retardation was 14.3 percent in the intervention group and 13.3 percent in the control group (odds ratio, 1.08; 95 percent confidence interval, 0.83 to 1.40). Adjustments for smoking, maternal age, previous cesarean section, obstetrical history, parity, interval since the birth of the previous child, alcohol consumption, and study site did not alter these results.The infants born to the women in the intervention group had a crude mean birth weight that was 19 g heavier (95 percent confidence interval, -29.3 to 67.3 g) than that of the infants of the women in the control group. After adjustment, the infants in the intervention group were 20.2 g heavier and 0.27 cm taller, and they had a mean gestational age that was 0.24 week longer; these differences were not statistically significant.
Analyses after stratification according to the preselected variables did not identify any statistically significant differences between the intervention and control groups in any of the principal outcome variables (Tables 4Table 4
Effect of Psychosocial Support during Pregnancy on Birth Weight and Gestational Age.* and 5Table 5
Effect of Psychosocial Support during Pregnancy on Birth Weight and Gestational Age, According to the Mother's Level of Psychosocial Support and Psychological Distress at Entry.*). Women with high levels of psychological distress, low levels of social support, or both also received no apparent benefit from the intervention in terms of the frequency of low birth weight, preterm delivery, or intrauterine growth retardation (Table 5). An exploratory post hoc analysis included only women from each group who received fewer than four prenatal visits. There were still no significant differences between the groups or patterns in the rate of low birth weight, prematurity, or intrauterine growth retardation. The sample sizes were very small, however (43 women in the intervention group and 46 women in the control group).Maternal and Neonatal Morbidity
The proportion of women admitted to the hospital for reasons other than delivery and their diagnoses were similar in the two groups, as were the rates of overall morbidity. The duration of postpartum hospitalization was 2.8±2.4 days in the intervention group and 2.8±2.5 days in the control group. Among the women who had vaginal deliveries, the proportion hospitalized for more than four days because of infection was 8.2 percent in the intervention group and 6.4 percent in the control group. The frequency of maternal complications and the use of health services at two and six weeks post partum were not significantly different in the two groups.
Evaluation of the infants at 40 days post partum demonstrated similar rates of respiratory infection, gastrointestinal diseases, nutritional complications, diarrhea, and dehydration in both groups. The overall frequency of hospital admission or visits to the hospital emergency department was 3.2 percent for the 953 infants born to women in the intervention group for whom follow-up data were available and 4.5 percent for the 949 comparable infants born to women in the control group (odds ratio, 0.68; 95 percent confidence interval, 0.41 to 1.13).
Discussion
In this large, randomized multicenter trial, intense formal psychosocial support offered through home visits to socially disadvantaged pregnant women did not improve the biologic outcomes of the pregnancies. The women had risk factors for the delivery of a low-birth-weight infant, high base-line anxiety scores, and low levels of social support — all presumably making them more responsive to this type of intervention.
The study was reasonably successful in carrying out the intervention as planned, and the intensity of the intervention was probably as high as is possible for programs conducted by public prenatal care services in most developing and developed countries. Furthermore, the intervention also attempted to increase the women's knowledge and use of health services, and efforts were made to make it easier for them to carry out the recommendations of health care workers. The intensity of the social-support intervention, the presence of a support person, and the strong elements of education and encouragement and facilitation of the use of health care resources made this intervention different from those described in previous reports.16 , 17 It is evident, however, that the intervention was not sufficient to overcome a lifetime of disadvantage and poor health.
Contamination of the control group by the education component of the intervention is unlikely. There were few opportunities for the women to contact each other because of the large number of patients served by these hospitals. Similarly, the hospital residents and staff rotated frequently, making it unlikely that they deduced which women were in the control group and provided them with additional care or psychosocial support.
Neither the comparisons between the groups after stratification according to the main predictive base-line variables nor the adjusted analyses changed our results in any significant way. Moreover, when we considered only women with high base-line levels of psychological distress, low levels of social support, or both — the group most likely to benefit from the intervention — the intervention still had no detectable effect.
We also calculated the magnitude of the effect of the social-support intervention, including data from a previously reported review,17 a recent report,16 and the results of this study and using a meta-analysis technique.18 There were 10 studies that provided data on preterm delivery and 11 that included low birth weight and type of delivery as outcome variables. These analyses yielded odds ratios of 0.93 (95 percent confidence interval, 0.82 to 1.05) for preterm delivery, 0.93 (95 percent confidence interval, 0.81 to 1.07) for low birth weight, and 0.96 (95 percent confidence interval, 0.86 to 1.07) for forceps delivery or cesarean section. Finally, eight studies with information on intrapartum use of anesthesia had a typical odds ratio of 0.91 (95 percent confidence interval, 0.81 to 1.03).
These findings therefore confirm that psychosocial support offered to pregnant women in various formats and settings does not appear to improve their neonates' birth weight or gestational age at delivery.16 , 17 , 19 20 21 Conversely, interventions involving the provision of supportive companions for the mother during labor have been shown to affect perinatal outcomes22 , 23 and could have a role in the care of pregnant women in specific short-term stressful situations.
Our intervention included a strong element of health and nutrition education, including culturally adapted, easy-to-follow graphic material. Information and advice were systematically presented during all home visits and focused on topics about which each woman needed the most information. Unfortunately, this component was not effective or, at least, was not sufficiently strong to overcome the negative effect of the preexisting risk factors.
Health education has been consistently recommended as an integral component of health services, particularly for disadvantaged populations and in developing countries. It is assumed that poor people fail to act or engage in risky behavior because they lack knowledge. However, a recent methodologic review found only very limited support for this recommendation in the literature, with only 3 of the 67 studies reviewed containing the four methodologic attributes required; only 21 percent were randomized studies with more than 60 cases or two clusters.24 , 25
Thus, before any special effort is made to incorporate major health-education components into prenatal care, there should be strong evidence of their benefits. If such evidence were a prerequisite, some elements of current prenatal care might not have been incorporated into clinical practice.
It could be argued that limiting entry into our study to women who sought prenatal care before 22 weeks of gestation and who had an adequate number of prenatal visits may have excluded women with the greatest need for this type of intervention. Our study was designed to evaluate the effect of psychosocial support in supplementing prenatal medical care. Women had to be contacted early and had to continue in the program for the intervention to be carried out as planned. It is possible that similar intervention targeted to women who received prenatal care only late in pregnancy, although necessarily less intensive, could be more effective because of these women's greater need. This possibility could be evaluated in future trials.
Although our intervention provided the opportunity for close interaction between the pregnant woman and the home visitor, no specific psychological treatment was provided, and no attempt was made to resolve major family or social problems. A more individualized program that provides, for example, long-term and intense psychological services, may be needed for a selected group of women. Long-term interventions appear to be necessary in other programs as well, such as nutritional supplementation during pregnancy.8
On the basis of data on large numbers of women studied in randomized trials, we conclude that there is no evidence that supplementing prenatal care with formal psychosocial support prevents preterm delivery and intrauterine growth retardation. Any new programs must be demonstrated to be effective before they can be recommended as part of routine prenatal care, even if the theory behind such interventions appears to be logically sound. In the meantime, clinics and hospitals should concentrate on consistently providing the components of prenatal care that have been proved to be effective.
Supported by a grant from the International Development Research Center, Ottawa, Canada.
*The other members of the Latin American Network for Perinatal and Reproductive Research are Laura González, Liana Campodonico, and Marcelo Barroso (Rosario, Argentina); Magda Victora, Jorge Beria, Ina Halal, and Aria Camporese (Pelotas, Brazil); Elba Díaz, Georgina Rojas, Dania Fresneda, and Manuel Garcia (Havana, Cuba); and Cecilia Garcia, Teresa Leis, and Lucille Atkin (Mexico City, Mexico).
We are indebted to Dr. Richard Osborn for his assistance throughout the study, to Dr. Adrian Grant for his comments on early versions of this paper, and to J. Starks for assistance in the preparation of the manuscript.
Source Information
From the Centro Rosarino de Estudios Perinatales, Rosario, Argentina (J.V., J.M.B.); Hospital America Arias, Ministry of Public Health, Havana, Cuba (U.F.); the Centro de Perquisas Epidemiologicas, Universidad Federal de Pelotas, Pelotas, Brazil (F.B., C.V.); and the Centro de Investigaciones en Salud Pública, National Institute of Health, Cuernavaca, and the National Institute of Perinatology, Mexico City, both in Mexico (A.L.). Address reprint requests to Dr. Villar at the Special Programme on Research, Development and Research Training in Human Reproduction, World Health Organization, 1211 Geneva 27, Switzerland.
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