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Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki (1956)

Chapter: ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY

« Previous: THE ANALYSIS OF THE BIRTHWEIGHT DATA
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
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Page 151
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 152
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 153
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 154
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 155
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 156
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 157
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 158
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 159
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 160
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 161
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
×
Page 162
Suggested Citation:"ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY." National Research Council. 1956. Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki. Washington, DC: The National Academies Press. doi: 10.17226/18776.
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Page 163

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Chapter XI ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY 11.1 The trait. — Although from its very first usage the Genetics Short Form included a question concerning death following delivery, the collection of data with reference to death after the first week following delivery was not originally systematic. However, the instruction to the midwives regarding promptly notifying the ABCC in the event of an abnormal preg- nancy termination included a statement regard- ing death during the first days of life. As the autopsy program developed, the midwives often voluntarily informed the ABCC of death at any time during and after the first week postpartum. The routine follow-up visit was usually made between the seventh and fourteenth postpartum days — sometimes later, usually in consequence of recurrent transportation crises in the "motor pool," seldom earlier, due largely to the system of collecting Genetics Short Forms from the midwives and also a natural and proper reluc- tance on the part of Japanese mothers, espe- cially during the winter months, to permit the examination of their children at an earlier date. At the time of this follow-up visit, any deaths which had occurred were noted. This system led to quite complete information regarding death during the first week of life. In the actual analysis, we have confined our attention to the occurrence of death during the first six days postpartum. In the strict sense, this is not the neonatal period, which is usually thought of as including the first month of life, but we shall apply the term "neonatal" to it as a matter of convenience. In addition to this information regarding neonatal death, there is available supplementary information from the "9-months program." As noted earlier, infants were selected for follow-up studies at age 9 months on the basis of the terminal digit in their registration num- bers. Thus, depending on the personnel and facilities available, one month an attempt might be made to re-examine all infants whose regis- tration number ended in 0 or 5, the next month 0, 5, or 9, etc. At the time of the contacts necessary to arrange for this examination, it could be determined if the infant had died in the interval between our initial examination and the time of the second contact. There is thus available supplementary information for 21,788 infants concerning the occurrence of death be- tween birth and the ninth month following de- livery. The latter figure is somewhat approxi- mate because of variations in the "contact day," but no bias exists with reference to parental radiation history. 11.2 The genetic argument for radiation-in- duced changes in the neonatal death rate. — The argument from which one might expect radiation-induced genetic changes in the neo- natal death rate is wholly analogous to the argu- ment for differences in the stillbirth rate with increasing parental exposure (see Sec. 9.2). Mutations detected in the first generation of offspring by a study of the neonatal death rate would consist largely of the dominant lethals (or possibly in a more strict sense the suble- thals) although some recessive lethals might also be recovered because of the fortuitous com- bination in some individuals of an induced lethal mutation with an allelic lethal mutation of spontaneous origin. Accordingly, we might expect as one manifestation of radiation-induced genetic damage an increase in the frequency of neonatal deaths with increasing parental ex- posure. 151

152 Chapter XI Genetic Effects of Atomic Bombs 11.3 Concomitant variables known to influ- ence the occurrence of a neonatal death. — The sources of extraneous variation affecting the frequency of neonatal deaths are not unlike those variables influencing the frequency of stillbirths (see Sec. 9.3). Among the con- comitant variables common to both of the afore- mentioned indicators are maternal disease (principally syphilis), nutrition, birth injury, maternal age, order of birth, and rate of repro- mother to infant with increasing maternal age. The age distribution among the exposure cells is such that this bias would tend to inflate the neonatal death rate among the non-exposed or less heavily exposed parents. It was felt that these effects could be ignored. 2. There is ample evidence attesting to the importance of nutrition and birth injury in the neonatal death rate, but these two variables will be ignored in our presentation because there 5.CH 4.5 4.0- 3.5 NEONATAL DEATHS (PER CENT) 2.5 2.O 1.5 1.0 0.5 PARITY IS 20 30 MOTHER'S AGE 40 FIGURE 11.1 — The distribution of the frequency of neonatal deaths by age of mother for specified parities. duction. In the case of neonatal death this list must be augmented by the addition of at least one more extraneous variable, namely, infantile infectious diseases. In the first six days of life, the principal infectious diseases, which could and frequently do lead to the death of an in- fant, are respiratory infections and infantile diarrhea. The observations and comments with regard to maternal disease, nutrition, and birth injury made in Chapter IX with regard to stillbirths are no less pertinent here. To recapitulate briefly, we noted that: 1. There existed a gradual but significant de- cline in the rate of transmission of syphilis from are no demonstrable or probable differences among exposure cells. With regard to the effect of maternal age and parity on the neonatal death rate the reader is referred to Figures 11.1 and 11.2 and Tables 11.1 and 11.2. The latter figure gives the distribution of the frequency of neonatal death by parity for specified maternal ages. The former figure gives the distribution of the frequency of neonatal death by maternal age for specified parities. From these two figures and tables we note that the effect of maternal age and parity on the frequency of neonatal death is strikingly similar to the effect of age and parity on the

Data Concerning Death During Period Following Delivery 153 stillbirth rate.1 We find that the age-specific parity distributions or the parity-specific age distributions of the frequency of neonatal death tend to be U-shaped. However, unlike the still- birth data the minima of the age-specific parity distributions appear quite similar, whereas the minima of the parity-specific age distributions tend to occur at a higher level with increasing 5.0-1 4.5 4.0- • 3.5- 3.0- exposure cells would require also taking into account variation in maternal age. However, as in the case of stillbirths, a partitioning of the data as elegant as that required to effect the "best" control would seriously jeopardize the validity of the tests because of (a) the large number of empty cells, and (b) the very small expected values in the bulk of the occupied cells. 2.5- NEONATAL DEATHS (PER CENT) 2.0- 1.5- 1.0 0.5- •4- •*• 2 H 7« 3 4 S 6 PARITY FIGURE 11.2 — The distribution of the frequency of neonatal deaths by parity for specified maternal ages. parity. These findings would suggest a signifi- cant effect of parity which varies by mother's age on the frequency of neonatal death (a rate of reproduction effect), but no significant inde- pendent effect of mother's age. This is consistent with Yerushalmy's (1938) observations in the United States. Now since the effect of parity is not independent of maternal age, adequate ad- justment to control variation in parity between 1 A full description of these data is to be published elsewhere. Accordingly, the data were further partitioned only with regard to parity. We recognized five parity classes, namely, parity 1, parities 2-3, 4-5, 6-7, and 8 and higher. The bias which might remain after this partitioning would be one difficult to specify adequately but probably would lead to an increase in neonatal mortality among the more heavily exposed cells because of increased maternal age within these latter cells. The possibility of a spurious irradiation effect

154 Chapter XI Genetic Effects of Atomic Bombs 1} TABLE 11.1 THE EFFECT OF MATERNAL AGE AT FIXED PARITY ON THE FREQUENCY OF NEONATAL DEATHS Total Normal Neonatal % births births deaths neonatal Parity 1 < 21 1,882 1,849 33 1.75 21-25 8,479 8,356 123 1.45 26-30 3,125 3,062 63 2.02 31-35 595 587 8 1.34 36-40 171 164 7 4.09 41+ 18 16 2 11.11 Total 14,270 14,034 236 — X2, = 21.293** IAD=. 08215 Parity 2 <21 415 413 2 21-25 6,572 6,482 90 26-30 6,294 6,225 69 31-35 1,399 1,383 16 36-40 360 353 41 + 46 46 Total 15,086 14,902 184 X24 = 4.818 IAD = .06543 Parity 3 <21 36 35 1 21-25 2,188 2,151 37 26-30 5,729 5,658 71 31-35 2,357 2.330 27 3^40 514 508 6 41 + 66 65 1 Total 10,890 10,747 143 X1, = 3.864 IAD = .06327 Parity 4 <21 4 4 21-25 472 460 26-30 2,828 2,788 40 31-35 2,487 2,455 32 36-40 736 728 8 41 + 83 82 1 Total 6,610 6,517 93 — Xf4 = 5.087 IAD = .06014 (>,, = .12044 = .26001 0.48 1.37 1.10 1.14 1.72 = .27488 2.78 1.69 1.24 1.15 1.17 1.52 =. 19843 2.52 1.41 1.29 1.09 1.20 AD .00808 .07422 .04877 .00793 .01797 .00733 .16430 .01684 .05416 .04273 .00585 .01127 .13086 .00374 .05859 .02997 .02799 .00531 .00094 .12654 .05783 .00230 .03262 .02569 .00183 .12028

Data Concerning Death During Period Following Delivery 155 TABLE \l.\- Continued Total births Normal births Neonatal deaths % neonatal 7.89 1.54 1.44 0.98 9.09 1.93 0.74 1.27 2.96 Parity 5 <21 .......................... — — — 21-25 ......................... 76 70 6 26-30 ......................... 975 960 15 31-35 ......................... 1,737 1,712 25 36-40 ......................... 823 814 9\ 41+ .......................... 95 95 — J Total ........................ 3,706 3,651 55 — X2, = 22.999** I»D = .09971 pT = .06753 Parity 6 <21 ......................... — — — — 21-25 ......................... 11 10 1 26-30 ......................... 259 254 5 31-35 ......................... 943 936 7 36-40 ......................... 785 775 10 41 + ......................... 135 131 4 Total ........................ 2,133 2,106 27 — X24 = 11.484* IAD =.18519 pT = . 03887 Parity 7 + <21 ......................... — — — — 21-25 ......................... 3 } — 1 26-30 ......................... 55 54 1J 31-35 ......................... 479 471 8 36-40 ......................... 1,167 1,146 21 41 + .......................... 483 476 7 Total ........................ 2,187 2,150 37 — X2S = .254 hn = .03506 pT = .03985 All parities <21 .......................... 2,337 2,301 36 21-25 ......................... 17,801 17,532 269 26-30 ......................... 19,265 19,001 264 31-35 ......................... 9,997 9,874 123 36-40 ......................... 4,556 4,488 68 41+ .......................... 926 911 15 Total ........................ 54,882 54,107 775 X2B = 4.641 I'AD (for age) =.07447 Heterogeneity x" = 65.158** DF=23 1.72 1.67 1.80 1.45 1.54 1.51 1.37 1.23 1.49 1.62 AD .08992 .00979 .01437 .08534 .19942 .03229 .06458 .18519 .00237 .08594 .37038 .00052 .00285 .03454 .03221 .07012 .00392 .02307 .01053 .02378 .00480 .00252

156 Chapter XI Genetic Effects of Atomic Bombs TABLE 11.2 THE EFFECT OF PARITY AT FIXED MATERNAL AGE ON THE FREQUENCY OF NEONATAL DEATHS Total births Normal births Mother's age: < 21 1 1.882 1,849 2 415 413 3 36 35 4+ 4 4 Total 2,337 2,301 X22 = 3.872 IAD =.12393 Mother's age: 21-25 1 8.479 8,356 2 6,572 6,482 3 2,188 2,151 4 472 460 5 76 70 6 ' 11 10 7+ 3 3 Total 17,801 17,532 X20 = 28.736* * IAD = .05452 Mother's age: 26-30 1 3,125 3,062 2 6,294 6,225 3 5,729 5,658 4 2,828 2,788 5 975 960 6 259 254 7+ 55 54 Total 19,265 19,001 X26 = 14.791* IAD = .09509 Mother's age: 31-35 1 595 587 2 1,399 1,383 3 2,357 2,330 4 2,487 2,455 5 1,737 1,712 6 943 936 7 + 479 471 Total 9,997 9,874 X1, = 3.589 IAD = .06433 Mother's age: 36-40 1 171 164 2 360 353 3 514 508 4 736 728 5 823 814 6 785 775 7+ 1,167 1,146 Total 4,556 4,488 X28= 11.456 ho = .14417 Neonatal deaths 33 2 36 123 90 37 12 6 269 63 69 71 40 15 5 1 264 8 16 27 32 25 7 8 123 7 7 6 8 9 10 21 68 neonatal 1.75 0.48 2.50 = .04258 1.45 1.37 1.69 2.54 7.89 7.14 = ..32435 2.02 1.10 1.24 1.41 1.54 1.93 1.81 pT = .35103 1.34 1.14 1.15 1.29 1.44 0.74 1.67 pT = . 18215 4.09 1.94 1.17 1.09 1.09 1.27 1.80 =. 08301 AD .11310 .12393 .01083 .24786 .01937 .03515 .01486 .01837 .01831 .00298 .10904 .07749 .06625 .02883 .00479 .00629 .00557 .00095 .19018 .00559 .00998 .01646 .01153 .02987 .03788 .01734 .12866 .06640 .02429 .02496 .04456 .04902 .02562 .05348 .28834

Data Concerning Death During Period Following Delivery 157 Mother's age: 41 + 1 2 3 4 5 6 7+ TABLE 112—Continued Total Normal births births 18 16 46 46 66 65 83 82 95 95 135 131 483 476 Neonatal deaths Total 24 = 3.781 926 911 IAD = .18815 All ages: 1 14,270 2 15,086 3 10,890 4 6,610 5 3,706 6 2,133 7+ 2,187 Total 54,882 X28 = 12.462' Heterogeneity x' = 53.763* * on the neonatal death rate due to a non-random distribution (by parental exposure) of contacts with the agents responsible for the more serious infectious infantile diseases such as the respira- tory infections and infantile diarrhea is difficult to evaluate. We are not aware of any widespread outbreaks of respiratory infections or diarrhea among the newborn infants of Hiroshima and Nagasaki during the interval 1948-1953. 11.4 The data. — In Tables 11.3 and 11.4 are given the distribution of neonatal deaths by sex of infant, parental exposure and city without and with allowance for parity. The corresponding analytical results are given in Tables 11.5 and 11.6. Let us consider first the evidence for an irradiation effect from the data prior to partitioning by parity. From inspection of Table 11.3 and from the results given in Table 11.5 we note a significant mother-father exposure interaction. The occurrence of this interaction considerably complicates further analysis of these data since, as in the non- orthogonal case of the analysis of variance, the disproportion among the numbers of observa- tions in the various ways of classification leads to distortion of main effects tests based upon the marginal totals, due to the unequal contributions to the marginal class totals. Under the circum- 14,034 14,902 10,747 6,517 3,651 2,106 2,150 4 4 7 15 236 184 143 93 55 27 37 % neonatal 3.13 1.52 0.56 2.96 1.45 = .01687 1.65 1.22 1.31 1.41 1.48 1.27 1.69 AD .06528 .00468 .12763 .12287 .05584 .37630 .04514 .03800 .01411 .00045 .00349 .00408 .00801 54,107 775 — — I%D (for parity) = .08320 DF = 23 stances it would seem that the most appropriate tests for those ways of classification other than those involved in the interactions, here mother's exposure and father's exposure, would be the sum of the chi-squares obtained by testing a given way of classification at each level of the ways of classification involved in the interac- tion. Thus, in this instance, the test of the city effect would be obtained by summing the six- teen chi-squares and their degrees of freedom obtained by testing the effect of city on the vari- ate at each of the sixteen mother-father levels. The disadvantage of this procedure is that all sixteen tests contribute equally to the sum, whereas the power of the individual tests will vary considerably. Ideally, perhaps, one would weight the individual contributions of these tests to the sum by their power functions. This has not been done, and hence the sum tests will probably be somewhat biased. When the data are analyzed as just outlined, for only one of the eight exposure tests when the exposure of one parent is held constant does a significant effect of mother's or father's ex- posure emerge. The weight this one positive finding should be given in the face of seven non-significant, similar tests is debatable. There are significant differences between the sexes but

158 Chapter XI Genetic Effects of Atomic Bombs TABLE 11.3 THE FREQUENCY OF NEONATAL DEATHS BY PARENTAL EXPOSURE, CITY, AND SEX OF INFANT (Unrelated parents) Male infants Hiroshima Fathers 1 2 3 4-5 Total fn 8,805 751 304 206 10,066 Jd IP 132 7 9 7 155 .0150 .0093 .0296 .0340 .0154 fn 2,760 909 190 116 3,975 2Jd 45 11 — 2 58 IP .0163 .0121 — .0172 .0146 Mothers JJ 1,081 16 .0148 219 258 79 1,637 20 2 .0078 2 IP .0253 .0122 fn 551 108 51 56 766 4-5-U IP 10 — 3 1 .0183 14 .0181 — .0588 .0179 f n 13,197 1,987 803 457 16,444 TotaU d 203 18 14 12 247 IP .0154 .0091 .0174 .0263 .0150 Male infants Nagasaki Fathers 1 2 3 4-5 Total r 'I3 IP 7,417 130 .0175 1,087 19 .0175 124 72 8,700 152 .0175 .0242 3 ,{3 4,732 80 .0169 2,055 31 .0151 2 .0146 137 103 7,027 113 .0161 IP I 3Jd 349 10 131 50 13 543 1 IP .0287 .0076 1 — — .0203 11 fn 274 55 18 15 362 4-5 -M IP 2 2 1 — 5 .0073 .0364 .0556 — .0138 f" 12,772 3,328 329 203 16,632 TotaU d 222 53 6 — 281 I IP .0174 .0159 .0182 — .0169

Data Concerning Death During Period Following Delivery 159 TABLE 11 .3 — Continued Female infants Hiroshima Fathers 1 2 3 4-5 Total f r " 8,086 711 271 177 9,245 'I? 87 11 5 2 105 .0108 .0155 .0185 .0113 .0114 2Jd fn 2,466 886 182 118 3,652 IP 32 12 1 — 45 .0130 .0135 .0055 — .0123 C fn 1,039 8 199 1 246 75 1,559 9 QJ -g . o LP .0077 .0050 — — .0058 fn 533 90 55 58 736 4-5 -M I? .0131 7 .0111 1 — — .0109 8 — — fn 12,124 1,886 754 428 15,192 TotaU d 134 25 6 2 167 IP .0111 Female infants .0133 .0080 .0047 .0110 Nagasaki Fathers 1 2 3 4-5 Total Jd f" 6,843 1,023 112 64 8,042 IP 82 12 2 1 97 .0120 .0117 .0179 .0156 .0121 f 4,373 1.967 131 70 6,541 1 60 26 2 — 88 LP .0137 .0132 0153 — .0135 |. J! 373 139 1 43 21 576 8 .0139 6 .0161 1 IP .0072 .0233 fn 272 58 1 16 13 359 4-5^ d LP f" 5 .0184 .0172 .0167 6 11,861 3,187 302 168 15,518 TotaU d IP 153 40 5 1 199 .0129 .0126 .0166 .0060 .0128

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Data Concerning Death During Period Following Delivery 161 TABLE 11.5 CHI-SQUARE ANALYSIS OF THE FRE- QUENCY OF NEONATAL DEATHS BY PARENTAL EXPOSURE, CITY, AND SEX (Unrelated parents) (a) 4X4 Source DF . . 63 x' 83974 P Total 05- 10 Interactions CS , first order 1 0 070 .70-80 CM 3 192 30- 50 CF .... . .. 3 5.336 .10-.20 SM . . . 3 2 202 .50-.70 SF . . . 3 5.224 .10-20 MF . . . 9 22 986 001-01 Main effect Mothers: s Fathers 1 1.223 .70-80 Fathers 2 j 4.365 .20-.30 Fathers 3 . . . 3 12.480 001-01 Fathers 4,5. ... . . . 3 4.378 20- 30 Fathers: Mothers 1. 3 6 258 10— 20 Mothers 2 3 5 280 10- 20 Mothers 3 . . . 3 7.132 .05-.10 Mothers 4,5 ... . . . 3 2.479 .30-.50 Sot:1 M,F, 1 13.296 < .001 M,F, 0 051 80-90 1 1 840 10-20 MjF, . 1 2 504 10-20 M,F, . . . 1 0.077 .70-.80 . . . 1 0.070 .80- 90 . . . 1 2.080 .10-.20 M, , ,F, . . . 1 0.204 .50-.70 M« F ' ' . . . 1 6266 01-02 Sum . 9 26.388 001-01 City: * M]Fj 1 2 048 .10-20 M,F, 1 0 091 70-80 M, , 5F, . . 1 1.837 .10-.20 MjF, , . . 1 0.361 .50-.70 M,F, . . . 1 0.168 .50-70 M,,,,tF, M,F, , , ... 1 . . . 1 3.265 0.780 .05-.10 .30-.50 . . . 1 1.093 .20-.30 ... 1 0.036 .80-.90 Sum . 9 9.679 .30-.50 TABLE 11.5 — Continued (b) 3X3 Source DF x" 35 39.587 1 0.161 2 0.425 2 4.354 2 2.258 2 5.007 4 5.441 Total , Interactions, first order CS CM CF SM MF Main effects Sex (S) • Mother's exposure — 2... 1 0.106 Mother's exposure — 3... 1 0.432 Mother's exposure — 4,5.. 1 2.604 Sum . City (C) • Mother's exposure — 2... 1 Mother's exposure — 3... 1 Mother's exposure — 4,5.. 1 Sum 3 Mother (M) 2 Father (F) ' Mother's exposure — 2... 2 Mother's exposure — 3... 2 P .50-.60 .50-.70 .80-.90 .10-.20 .30-.50 .05-.10 .20-.30 .70-.80 .50-.70 .10-.20 3 3.142 .30-.50 Sum ' Adjusted for mothers. 1.005 0.454 0.980 2.439 6.216 3.708 1.108 Mother's exposure — 4,5.. 2 2.421 .30-.50 .50-.70 .30-.50 .30-.50 .02-.05 .10-.20 .50-.70 .20-.30 6 7.237 .20-.30 • To increase the numbers of observations, cate- gories 3, 4, and 5 have been pooled in these tests.

162 Chapter XI Genetic Effects of Atomic Bombs TABLE 11.6 CHI-SQUARE ANALYSIS OF THE FRE- QUENCY OF NEONATAL DEATHS BY PARENTAL EXPOSURE, CITY, AND PARITY (Unrelated parents) Source DF x* P Total 159 189.601 .05-.10 Interactions, first order CM 3 3.192 .30-.50 CF 3 4.855 .10-.20 CP 4 14.401 .001-.01 MF 9 22.986 .001-.01 MP 12 21.436 .02-.05 FP 12 13.334 .30-.50 Main effects (only CP interaction taken into account) Parity (P) Hiroshima (H) 4 5.872 .20-.30 Nagasaki (N) 4 32.045 < .001 City (C) Parity Class — 1 1 18.585 < .001 Class — 2 1 0.458 .30-.50 Class — 3 1 0.420 .50-.70 Class —4 1 1.720 .10-.20 Class—5 1 0.200 .50-.70 Mother (M) H: Parity Class—1 3 11.753 .001-.01 Class — 2 3 3.424 .30-.50 Class — 3 3 0.809 .80-.90 Class — 4 3 2.882 .30-.50 Class —5 3 0.775 .80-.90 N: Parity Class — 1 3 5.235 .10-.20 Class — 2 3 1.977 .50-.70 Class —3 3 2.552 .30-.50 Class — 4 3 2.409 .30-.50 Class —5 3 4.662 .10-.20 Sum 30 36.478 .10-.20 Father (F) H: Parity Class — 1 3 4.260 .20-.30 Class — 2 3 2.387 .30-.50 Class — 3 3 10.236 .01-.02 Class — 4 3 2.559 .30-.50 Class — 5 3 1.976 .50-.70 N: Parity Class — 1 3 1.085 .70-.80 Class — 2 3 4.322 .20-.30 Class —3 3 3.156 .30-.50 Class — 4 3 2.322 .50-.70 Class — 5 3 0.846 .80-.90 Sum 30 33-149 .30-.50 not the cities. Omission of the category 1 parents from the analysis results in the disappearance of the M-F interaction (Table 11.5b). As be- fore, there is no significant effect of father's exposure but now a barely significant effect of mother's exposure appears. From Tables 11.4 and 11.6, we note that when neonatal deaths are further partitioned by parity rather extensive heterogeneity in the data is revealed. Both the city-parity and mother-father interactions are significant. To adjust the main effects tests as indicated in Chapter VI leads, in this instance, to such ex- tensive partitioning as to seriously jeopardize the validity of the tests. However, one could adjust for one of the interactions at a time. Accordingly, two sets of "main effects" tests could be generated. If one ignores the mother- father interaction, the main effects tests of city, parity, and exposure would be as given in Table 11.6. If the city-parity interaction were ignored, the tests of exposure and city would be as given in Table 11.5a, and there would, in addition, be a test of parity. One must obviously view the results of these two sets of tests as approximate. However, in neither instance does evidence emerge indicating a significant, consistent effect of parental exposure. The results from the "at-birth" examinations are corroborated by the findings at 9 months of age, presented in Table 11.7. The reader should note the following departures from the usual classifications of the 9-months data: (1) sex of infant is ignored, (2) exposure categories 3, 4, and 5 have been pooled, and (3) deaths from birth to 9 months are recorded. The purpose of these latter procedures was to bring to bear on the problem of infant mortality fol- lowing dissimilar exposure experiences on the part of the parents, the largest possible number of observations. No attempt has been made to control concomitant variation which would pre- sumably be no less of a problem here than else- where in these data, and would, in the main, tend to inflate the death rate among infants born to the more heavily exposed parents. The analy- sis of these data is presented in Table 11.8. We note no effect of city, maternal or paternal exposure, or evidence of heterogeneity between the cities or exposure cells. 11.5 Summary. — No consistent, significant effect of parental exposure on neonatal mortality emerges from the data obtained in Hiroshima and Nagasaki on deaths occurring in the first six days postpartum. Analysis of neonatal and infantile mortality obtained at the time of the 9-months examination fails to disclose an effect of parental exposure on infant survival. No consistent exposure trend is exhibited by these data.

Data Concerning Death During Period Following Delivery 163 TABLE 11.7 THE FREQUENCY OF DEATHS BETWEEN BIRTH AND NINE MONTHS OF AGE BY PARENTAL EXPOSURE AND CITY (Unrelated parents) Hiroshima Mothers 1 2 3-4-5 Total n 5,678 1,803 1,064 8,545 i- d 254 85 48 387 P .0447 .0471 .0451 .0453 n 482 528 188 1,198 2- d 24 27 8 59 I f .0498 .0511 .0426 .0492 1 fn 319 186 264 769 £ 3-4-5-M 16 8 14 38 IP .0502 .0430 .0530 .0494 Total J d f° 6,479 294 2,517 120 1,516 70 10,512 484 I IP .0454 .0477 .0462 .0460 Nagasaki Mothers i 2 3-4-5 Total fn 4,225 2,599 396 7,220 Id 209 125 25 359 IP .0495 .0481 .0631 .0497 fn 58) 1,051 117 1,751 21d 20 61 2 83 • IP .0343 .0580 .0171 .0474 J. 0tt 3-4-5 ^d fn 120 149 66 335 £ IP 4 7 5 16 .0333 .0470 .0758 .0478 fn 4,928 3,799 579 9,306 Total J d IP 233 193 32 458 .0473 .0508 .0553 .0492 TABLE 11.8 ANALYSIS OF THE FREQUENCY OF DEATHS BETWEEN BIRTH AND NINE MONTHS OF AGE, BY PARENTAL EXPOSURE AND CITY (Unrelated parents) Source Total DF 17 Interactions, first order CM 2 CF 2 MF 4 Main effects City 1 Mothers 2 Fathers 2 X' 13.146 0.382 0.658 4.647 1.097 1.081 0.087 P .70-.80 .80-.90 .70-.80 .30-.50 .20-.30 .50-.70 .95-.9S

Next: THE ANALYSIS OF THE ANTHROPOMETRIC DATA »
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