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Comparison of Stillborn Birth Weights and Postmortem Weights

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Halit Pinar MD*, Murat Iyigun PhD**

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*Department of Pathology and Laboratory Medicine

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Division of Perinatal and Pediatric Pathology

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Alpert School of Medicine at Brown University

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**Department of Economics University of Colorado, Boulder

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Corresponding author:

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Halit Pinar, MD

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Women and Infants Hospital

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101 Dudley Street,

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Providence, RI 02905

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Email: [email protected]

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Phone: (401) 274 1122, extension 1190

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Fax: (401)

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Abstract Objective: To compare the agreement (concordance) of fetal birth weights (BW), and the postmortem weights (BMW) of stillborns. Methods: Birth weights obtained by the nurses in the labor and delivery

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(LDR) were compared with the weights obtained prior to the postmortem

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examination prospectively in 110 stillborns. The affects of gestational age,

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degree of maceration and time elapsed from delivery to postmortem

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examinations were also examined.

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Results: There were 45 female and 65 male stillborns in the study. The

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gestational ages ranged from 17 to 40 weeks. Degree of maceration ranged from

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0 to 5; 0 being no maceration and 5 representing the most extreme condition,

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which was mummification. There was a decrease in the weights of all stillborns

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when their birthweights and postmortem weights were compared. The average

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relative weight loss was 7.3%. When all the variables were examined, only the

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degree of maceration was identified to play a significant role (p=008). Higher

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the degree of maceration meant more weight loss.

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Conclusion: There is significant discrepancy between the birth and

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postmortem weights of stillborns. While gender, gestational age and time

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elapsed from delivery to postmortem examination did not have a significant

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impact, degree of maceration affected this observed weight loss. In stillborns

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birth weights are more accurate than the postmortem weights.

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Introduction

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Body weight is one of the most significant parameters in the assessment of

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growth in the developing organisms. Postmortem examination plays an

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essential role in our efforts to elucidate the causes of stillbirth. Measuring the

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body weight is an integral part of this process. Initial weights of the stillborns

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are routinely obtained in the delivery room usually within minutes of delivery.

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Due to our initial observations of inconsistencies in these two values, we

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decided to compare the weights obtained at birth and before the postmortem

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examination in a prospective manner. The possible effects of gestational age,

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duration of the elapsed time from delivery to the postmortem examination and

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degree of maceration on the weight of the fetus were analyzed.

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Methods

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Over a period of a year beginning in January 2002, 110 stillborns were

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prospectively evaluated for birth and postmortem weights, gestational age,

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degree of maceration and the time elapsed from delivery to the time of the

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postmortem examination. The birth weights of these stillborns obtained

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immediately after delivery and they were weighed again before the initiation of

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the postmortem examination. Clinically determined gestational ages were used 3

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in our evaluations. Degree of maceration was determined using a standardized

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grading system that ranged from 0 (no maceration) to 5 (maximum degree of

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maceration – mummification) (Table 1). The scales that were used in both

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locations were the same make and model (Fisher-xxxxx, model xxxx) and had

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been maintained by the same team of technicians. The temperature of the

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morgue was monitored as part of the CAP requirements and did not show any

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aberrations. The ambient room temperatures were similar in both locations and

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did not differ between seasons. Immediately after delivery the fetuses were

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weighed with one or two plastic cord clamps and one or two absorbent sheets

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then they were placed in special body bags (made by xxxxx®) and kept in this

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manner in the morgue. Postmortem weights were obtained without the body

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bag but with the cord clamps and absorbent pads. The weights were recorded in

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grams and values rounded up to two decimal places.

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Statistical analysis was performed using

Results

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There were 45 female and 65 male stillborns comprising the 110 cases in

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the study. Gestational ages ranged from 17 to 40 weeks. There were 12 cases

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≤19 weeks gestational age. Days elapsed from delivery to the postmortem

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examination ranged from 0 to 5. The average was 000 days. There was only one

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case that underwent a postmortem examination after 5 days. Placentas were 4

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available and examined in all the cases. Distribution of major diagnoses made

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after the postmortem and placental examination is shown in Table 2.

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In this prospective study when we compared the birth weights with

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postmortem weights of 110 stillborns, we found that relative postmortem

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weights were consistently 7.3% was lower than their birthweights. Gender,

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birthweight, gestational age and elapsed time from delivery to the postmortem

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examination did not have a measurable effect on the weight loss. Stillborns, who

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had a higher degree of maceration lost more weight.

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Discussion

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The first essential step when examining the embryo, fetus, or infant is to

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determine where the case fits in the scale of human development. Typically,

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human form, function, and size change in a normal and predictable manner

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from conception. If pathologic processes are to be understood, the changes

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during normal growth and development must have reference either to the age of

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the subject or to the stage of gestation. The most obvious change with time is an

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increase in size or mass, and the simplest view of human fetal and infant

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development would regard weight as the main criterion needed for the

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assessment of fetal maturity. Small newborns have more significant morbidity

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and mortality than individuals in any other comparable time of life [1-3], and

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the smaller the baby, the greater the risk. Premature stillborns weigh less than their liveborn counterparts. For similar reasons, weight plays a major role in the evaluation of stillborns

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in attempts to identify the cause and the classification of death. In the absence

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of reliable dates, the weights of the stillborns are used to distinguish a second

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trimester spontaneous abortion from a stillbirth. Currently in the United States

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the most common definition of stillbirth is a fetal death occurring at ≥20 weeks

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gestational age or ≥350 g birth weight. So the weight of the stillborn, especially

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when the gestational age is not known, is especially significant and weighing

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errors result in unwanted consequences.

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It is a known fact that the bodies if left exposed to the forces of nature are

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affected according to the prevailing conditions. In dry and hot climates in the

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loss of water and weights is fast. In wet and hot climates it takes longer for the

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body to decompose. In wet and cold climate the decomposition takes even

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longer. During the interval from fetal death until delivery, the retained fetus

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undergoes maceration, a progressive deterioration of external and internal

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macroscopic and microscopic features. Maceration is characterized by softening

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and peeling of the skin, discoloration and softening of viscera, and fluid

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accumulation in body cavities. These changes are nonputrefactive and result

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from fetal immersion in amnionic fluid and digestion of fetal tissues by autolytic

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enzymes.

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The most likely explanation of the effects of maceration after delivery is

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fluid loss from the fetal body surface. In advanced stages of maceration, loss of

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epidermis increases. This results in the increase of the raw area where fluid can

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be lost in some manner. Despite the stillborn were wrapped, placed in special

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body bags and preserved in temperature-controlled environments, fluid loss

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from these exposed areas could not be avoided. Since the bodies were wrapped

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in special absorbent sheets, fluid loss was probably in the form absorption

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rather than evaporation. Although in adults small fluctuations of weight do not

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carry any clinical significance, in the fetal period any error in the measurement

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of weights will carry significant consequences.

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In conclusion, we have shown the discrepancy between the birth and

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postmortem weights of the stillborns and we are recommending to use the

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birthweights in the investigation of the stillbirths whenever they are available.

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References

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beginning and end of labor. Int J Gynaecol Obstet. 2008;101(2):133-6.

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Pinar H. Postmortem findings in term neonates. Semin Neonatol 2004;4:289302. Potter EL, Craig JM. Postmortem examination. In: The pathology of the fetus and the infant. 3rd ed. Chicago: Year Book Medical Publishers. 1975:84-5. Shanklin DR. Cimino DA, Lamb TH. Fetal maceration: I. An experimental sequence in the rabbit. Am J Obstet Gynecol 1964;88:213-23. Shanklin DR. Fetal maceration: II. An analysis of 53 human stillborn infants. Am J Obstet Gynecol. 1964;88:224-9. Smith GCS. First trimester origins of fetal growth impairment. Seminars Perinatol. 2004;28(1):41– 50. Strachan GI. The pathology of foetal maceration: A study of 24 cases. Br Med J 1922;2:80-2. Wigglesworth JS. The macerated stillborn fetus. In: Wigglesworth JS. Perinatal pathology. Philadelphia, WB Saunders, 1984,84-92.

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Table 1. Description of grades of maceration Physical Findings at PM Examination

Grade

No maceration. Tissue appears normal.

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Desquamation involving ≤ 1% of total body surface and brown-red discoloration of umbilical cord stump. Tissue appears red/pink and fresh with focal discoloration.

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Desquamation of face, abdomen or back involving ≥1% and ≤5% total body surface. Tissue appears red/pink and fresh with focal discoloration and serous fluid collection.

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Desquamation involving > 5% of body surface. Tissue appears red/pink and mixed with brown.

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Total brown skin discoloration. Tissue appears brown/gray.

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Mummification. Tissue appears gray.

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Table 2. The distribution of diagnoses of the 000 stillborns in the study

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