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Glossary Abruptio placentae premature detachment of the placenta. Balance study a method for estimating nutrient requirements by measur- ing all dietary intake and physiologic loss of the nutrient and comparing intake with loss. Bioavailability proportion of a nutrient absorbed from food and available for physiologic function. Body mass index (B MI) an expression of body weight for height used for children and adults. In this report, metric units are used, namely, BMI = [(kgim2) x 100] Carotene a precursor of vitamin A, sometimes called provitamin ~ Case-control study a study in which individuals with a particular condition (the cases) are selected for comparison with a series of individuals in whom the condition is absent (the controls). Cases and controls are compared with respect to exposures believed to be relevant to the development of the condition being studied. Ceruloplasmin a protein that carries the majority of the copper in the blood. Chelator a substance that binds metals (e.g., trace elements such as cop- per). 443
444 GLOSSARY Confounding variable a variable that biases the apparent relationship between an exposure (putative cause) and outcome (putative effect) under study. ~ qualify as a confounder, a variable must itself be a cause of the outcome and associated with the exposure but must not lie on the causal path between exposure and outcome. Congenital anomalies birth defects. Consequences health outcomes (effects) caused by the determinants. Determinants causal (etiologic) factors. Disproportionality the condition of having a low ponderal index (defined below). Dizygotic twins twins who are the product of two ova, often called frater- nal twins; of monozygotic twins. Effect modifier a factor that increases or decreases the magnitude of the effect of a determinant on a particular consequence. Embryo the developing organism from 1 week after conception to the end of the second month of gestation. Emb~yogenesis, period of the period during which the embryo develops, i.e., from the first week through the second month of gestation. See embryo. Essential amino acids amino acids with essential functions that cannot be synthesized by humans. See nonessential amino acids. Estrus the period of ovulation and sexual activity in nonhuman female animals. Etiologic fraction population attributable risk, that is, the proportion of all cases of a disease or other condition in a specified population that is attributable to an exposure. Factorial approach a method for estimating nutrient requirements by summing the estimated amounts of nutrient required for each of several purposes, e.g., replacement of endogenous loss and growth. Fetal alcohol syndrome a syndrome related to alcohol use during preg- nancy and characterized by prenatal or postnatal growth retardation, distinct facial anomalies, and mental deficiency. Fetopelvic disproportion a disparity between the size of the mother's pelvis and the size, shape, or position of the head of the fetus. This can result in prolonged labor and inability to deliver vaginally. Often called cephalopelvic disproportion. Fetus the developing organism in the human uterus after the second month of gestation.
GLOSSARY 445 Functional measurements of nutritional status tests to determine the adequacy of nutritional status to support the functions of subcellular constituents, cells, tissues, organs, biologic systems, or the whole body. Gestational duration the duration of pregnancy, usually calculated from the first day of the last normal menstrual period to delivery. Normal gestational durations average approximately 280 days. Gestational weight gain weight gained between conception and delivery. Ordinarily it includes maternal body weight and the weight of the products of conception. See discussion in Chapter 4. Goitrogens gland. substances that cause goiters or enlargement of the thyroid High birth weight infant birth weight greater than 4,000 g. Homeostatic pertaining to a stable state of the internal environment of the body that is maintained by dynamic processes of feedback and regulation. Hyperemesis gravidarum nancy. severe and prolonged vomiting during preg Hypocalciuria a low concentration of calcium in the urine. Infant mortality rate deaths during the first year of life per 1,000 live births. Intrauterine growth retardation lower-than-expected birth weight for a given gestational age. Usually defined as a birth weight below the 10th percentile for gestational age based on a given reference population and, hence, often used synonymously with small-for-gestational age. Keshan disease a serious, often fatal cardiomyopathy resulting from selenium deficiency. Lactation performance degree of success of breastfeeding, as determined by measurements such as milk volume, milk composition, duration of breastfeeding, and infant growth. Lactose intolerance a condition in which the intestinal enzyme lactase, which breaks down lactose to glucose plus galactose, is lacking; this may lead to cramps and diarrhea after consumption of certain lactose- containing foods (e.g., milk). Large-for-gestational age usually defined as birth weight above the 90th percentile for gestational age, based on a given reference population. Low birth weight infant birth weight less than 2,500 g. Menarche the initiation of menstruation.
446 GLOSSARY Menorrhagia excessive menstrual blood loss (>80 ml of menstrual blood per month). Micronutrients vitamins and minerals. Monozygotic twins originating from a single fertilized ovum, applied to identical twins; of dizygotic. Multiple pregnancy carrying more than one fetus, e.g., twins or triplets. Neonatal during the first 28 days after birth. Net weight gain total gestational weight gain minus the infant's birth weight. Nonessential amino acids amino acids with essential functions that can be synthesized by humans if suitable sources of carbon, nitrogen, and energy are available. Odds ratio the ratio of the odds of a condition occurring in exposed individuals compared with the odds in unexposed persons; generally used as an approximation of the relative risk Optimally grown infants defined in this report as an infant born at week 39 to 41 of gestation with a birth weight between 3,000 and 4,000 grams. Parity the number of children previously born to a woman. Periconceptional period a period from 1 to 3 months prior to gestation through the first 6 weeks of gestation. Pica ingestion of nonfood substances such as laundry starch and clay. Ponderal index an expression of weight for height used mainly for infants. In newborns, the index is usually expressed as birth weight in grams x 100 divided by the birth length in centimeters cubed. Postterm birth birth occurring after a gestation of 42 or more weeks. Preeclampsia _, ~7 hypertension accompanied by generalized pitting edema or proteinuria after the twentieth week of gestation. Preterm birth ~ ~ ~ ~ ~ ~ Primigravida a woman during her first pregnancy. Priminara ^ ~ - ~ ~ran . i. birth occurring after a gestation of less than 37 weeks. ~ woman woo nas produced one ow-g 1nIant for alter week 20 of gestation), regardless of the infant's viability. Rate of weight gain per week weight gained over a specified period divided by the duration of that period in weeks. Recurrent neural tube defect more than one child with a neural tube defect born to the same parents. Retinol preformed vitamin ~
GLOSSARY 447 Reverse causality the erroneous inference that a factor under study causes a given outcome when, in fact, the factor is an effect (consequence) of that outcome. The error arises because of failure to ensure that exposure to the factor actually preceded development of the outcome. Shoulder dystocia difficulty in delivering the shoulders of the fetus through the birth canal after its head has emerged. Small-for-gestational age see Intrauterine growth retardation. Spontaneous abortion miscarriage. Stadiometer a device for measuring height. Static measurements of nutritional status determination of overt signs of clinical deficiency and of nutrient or metabolite levels in blood or tissues. Teratogenic causing deformities in the fetus. Thermogenesis heat production (energy expenditure) following the in- gestion of food or exposure to cold above that produced by basal metabolism. Toxemia (eclampsia) coma and convulsive seizures occurring between approximately the twentieth week of pregnancy and the end of the first week postpartum. Turnover utilization and replacement (of nutrients). Very low birth weight infant birth weight less than 1,500 g. Vitamer any one of a number of compounds that have specific vitamin activity.