Intrauterine growth retardation and preterm delivery: prenatal risk factors in an indigent population Shi Wu Wen, MS: Robert L. Goldenberg, MD: Gary R. Cutter, PhD: Howard J. Hoffman, MA,c and Suzanne P. Cliver, BAa
Birmingham, Alabama, and Bethesda, Maryland Prenatally ascertained risk factors for low birth weight were evaluated in a population of 17,000 indigent women for their specific effect on intrauterine growth retardation and on the rate of preterm delivery. In a univariate analysis, intrauterine growth retardation occurred more frequently in women who were black, single, primiparous, < 17 or >30 years old. short, thin, had a previous preterm delivery. consumed alcohol, took drugs, or gained limited weight. Preterm delivery occurred significantly more frequently in women who were black. single, thin, 30 years old, had less than a twelfth grade education, or gained limited weight. In logistic regression analyses. race, parity, maternal age, a history of preterm delivery, smoking, short stature, low weight, and low weight gain remained significant risk factors of intrauterine growth retardation. Of these factors, smoking, short stature, low weight, and low weight gain showed the greatest correlation. Factors significantly related to preterm delivery included black race, single marital status, younger or older ages, previous preterm delivery, smoking, low weight, and very low or high weight gain. A previous preterm delivery and very low maternal weight had the greatest correlation. Identification of specific risk factors of both intrauterine growth retardation and preterm delivery should aid in the development of strategies to reduce the prevalence of these conditions. (AM J OBSTET GYNECOL 1990;162:213-8.)
Key words: Intrauterine growth retardation, preterm delivery. low birth weight
Low birth weight (LBW) and its two component parts. preterm delivery and intrauterine growth retardation (IUGR), are major predictors of perinatal mortality and morbidity. 1 However, because of the frequent difficulty in the determination of an accurate gestational age, many previous studies that examined risk factors of LBW have not tried to distinguish between infants who were preterm or IUGR.' Other studies have evaluated risk factors of each condition individually,"· but rarely have the risk factors of IUGR and preterm delivery been studied in the same population. Therefore, we considered it important to examine a number of factors previously reported to be associated with LBW and to concurrently determine the effect of these factors on both IUGR and preterm delivery in women in whom a great deal of effort had been given to gestational age determination.' Identification of specific risk factors for both IUGR and preterm delivery
From the Pennatal Epldemwlogy Unit. Department of Obstetncs and G_~necology," and School of Publzc Health,' Universzty of Alabama at Bzrmingham, and Biometry Branch, PreventIOn Research Program, NatIOnal Instztute of Chzld Health and Human Development, Natwnal Institutes of Health.' Supported In part by Natwnal Institutes of Health contract NO I-HD-4-2811. Reprint requests: Robert L. Goldenberg, MD, Department of Obstetncs and Gynecology, Unzverslt.~ of Alabama at Bmmngham. Umversity StatIOn. Bmnzngham. AL 35294. 611 /15545
should aid in the development of strategies and programs to reduce the prevalence of these conditions.
Material and methods Women seen for prenatal care and delivered of infants at the University of Alabama or Cooper Green Hospitals in Birmingham. Alabama, from January 1983 through December 1987 were included in this study. Women without prenatal care «2%), those transferred for delivery of infants only, those with diabetes, and those whose pregnancies involved multiple births, fetal death, and congenital malformation were later excluded from the study. As a result, 17,149 deliveries were analyzed. Characteristics studied included genetic and constitutional factors such as infant sex and maternal height, demographic factors such as mother's race, age, educational level, and marital status, obstetric factors such as parity and previous preterm delivery, nutritional factors such as maternal weight and weight gain, and toxic exposures such as cigarette smoking and alcohol and drug consumption. The data, collected prospectively but examined retrospectively, came from an automated medical record. 6 Quantification of the amount of cigarette smoking, alcohol, and drugs involved was not available. Height and prepregnancy weight were based on patient reports. Because many patients did not report a prepregnancy weight but nearly all had their weight recorded at the first visit, and because the analysis of both measure213
214 Wen et al.
January 1990 Am J Obstet Gynecol
Table I. Percentage of the study population with certain characteristics, and of these, the percentage with IUGR and preterm delivery Characteristic
Total population Race White Black Parity 0 1 >1 Marital status Married Unmarried Education (yr) 12 Maternal age (yr)
Birmingham, Alabama, and Bethesda, Maryland Prenatally ascertained risk factors for low birth weight were evaluated in a population of 17,000 indigent women for their specific effect on intrauterine growth retardation and on the rate of preterm delivery. In a univariate analysis, intrauterine growth retardation occurred more frequently in women who were black, single, primiparous, < 17 or >30 years old. short, thin, had a previous preterm delivery. consumed alcohol, took drugs, or gained limited weight. Preterm delivery occurred significantly more frequently in women who were black. single, thin, 30 years old, had less than a twelfth grade education, or gained limited weight. In logistic regression analyses. race, parity, maternal age, a history of preterm delivery, smoking, short stature, low weight, and low weight gain remained significant risk factors of intrauterine growth retardation. Of these factors, smoking, short stature, low weight, and low weight gain showed the greatest correlation. Factors significantly related to preterm delivery included black race, single marital status, younger or older ages, previous preterm delivery, smoking, low weight, and very low or high weight gain. A previous preterm delivery and very low maternal weight had the greatest correlation. Identification of specific risk factors of both intrauterine growth retardation and preterm delivery should aid in the development of strategies to reduce the prevalence of these conditions. (AM J OBSTET GYNECOL 1990;162:213-8.)
Key words: Intrauterine growth retardation, preterm delivery. low birth weight
Low birth weight (LBW) and its two component parts. preterm delivery and intrauterine growth retardation (IUGR), are major predictors of perinatal mortality and morbidity. 1 However, because of the frequent difficulty in the determination of an accurate gestational age, many previous studies that examined risk factors of LBW have not tried to distinguish between infants who were preterm or IUGR.' Other studies have evaluated risk factors of each condition individually,"· but rarely have the risk factors of IUGR and preterm delivery been studied in the same population. Therefore, we considered it important to examine a number of factors previously reported to be associated with LBW and to concurrently determine the effect of these factors on both IUGR and preterm delivery in women in whom a great deal of effort had been given to gestational age determination.' Identification of specific risk factors for both IUGR and preterm delivery
From the Pennatal Epldemwlogy Unit. Department of Obstetncs and G_~necology," and School of Publzc Health,' Universzty of Alabama at Bzrmingham, and Biometry Branch, PreventIOn Research Program, NatIOnal Instztute of Chzld Health and Human Development, Natwnal Institutes of Health.' Supported In part by Natwnal Institutes of Health contract NO I-HD-4-2811. Reprint requests: Robert L. Goldenberg, MD, Department of Obstetncs and Gynecology, Unzverslt.~ of Alabama at Bmmngham. Umversity StatIOn. Bmnzngham. AL 35294. 611 /15545
should aid in the development of strategies and programs to reduce the prevalence of these conditions.
Material and methods Women seen for prenatal care and delivered of infants at the University of Alabama or Cooper Green Hospitals in Birmingham. Alabama, from January 1983 through December 1987 were included in this study. Women without prenatal care «2%), those transferred for delivery of infants only, those with diabetes, and those whose pregnancies involved multiple births, fetal death, and congenital malformation were later excluded from the study. As a result, 17,149 deliveries were analyzed. Characteristics studied included genetic and constitutional factors such as infant sex and maternal height, demographic factors such as mother's race, age, educational level, and marital status, obstetric factors such as parity and previous preterm delivery, nutritional factors such as maternal weight and weight gain, and toxic exposures such as cigarette smoking and alcohol and drug consumption. The data, collected prospectively but examined retrospectively, came from an automated medical record. 6 Quantification of the amount of cigarette smoking, alcohol, and drugs involved was not available. Height and prepregnancy weight were based on patient reports. Because many patients did not report a prepregnancy weight but nearly all had their weight recorded at the first visit, and because the analysis of both measure213
214 Wen et al.
January 1990 Am J Obstet Gynecol
Table I. Percentage of the study population with certain characteristics, and of these, the percentage with IUGR and preterm delivery Characteristic
Total population Race White Black Parity 0 1 >1 Marital status Married Unmarried Education (yr) 12 Maternal age (yr)
