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Incidence of congenital malformations in Tokyo Metropolitan Hospitals, 1979–1993
ELSEVIER
Brain & Development
Q
1996; 18: 230-233
Short communication
Incidence of congenital malformations in Tokyo Metropolitan Hospitals, 1979- 1993 Kyoko a Department
Kato a,* , Keiko Fujiki
b
ofNeurology,Tokyo
Metropolitan Institutefor Neuroscience, 2-6 Musashidai, Fuchu-city, Tokyo 183, Japan b Department of Ophthalmology, Juntendo Unicersity School of Medicine, Tokyo 113, Japan Received 3 1 March 1995; accepted
I8 September 1995
Congenital malformations in all babies delivered at 11 Tokyo Metropolitan Hospitals (TMH) (8 hospitals since July 1989) for 15 years, January 1979 to December 1993, were monitored. Congenital malformations found within 7 days after birth were observed in 2085 babies (1.5%) of 138544 births including stillbirths after 16 weeks gestation. The prevalence rates of selected malformations were calculated and compared in the 5-year periods of 1979-1983, 1984-1988 and 1989-1993. There was no typical secular trend in prevalence rates of malformations except for the heart and circulatory system, which showed an increase because of the recent progress in prenatal diagnosis of these malformations. The specificity of the TMH Monitoring System is also discussed. Keywords;
Monitoring;
Congenital
malformation;
Tokyo Metropolitan
Hospitals;
1. INTRODUCTION A birth defect monitoring program is one of the most important strategies for detecting the emergence of new mutations, teratogens or new abnormalities in newborn babies. It can also be used in evaluating any possible effect of preventive measures against the occurrence of congenital malformations in general. For these purposes, congenital malformations have been monitored in all babies delivered at the Tokyo Metropolitan Hospitals (TMH) since April 1978 [l-3]. In the present study, a secular trend was analyzed every 5 years of prevalence of congenital malformations in all babies delivered in TMH during the period 1979- 1993.
2. SUBJECTS
AND METHODS
The data were collected by visiting the hospitals every l-2 months since the TMH monitoring system was started in April 1978. The gestational age (weeks), birth weight, maternal age at birth, congenital malformation of newborn babies and other relevant information were registered. Congenital malformation was defined in this study as a gross physical or anatomical
* Corresponding
author. Fax: (81) (423) 21-8678.
0387-7604/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0387-7604(95)00113-l
Prevalence
rate; Secular trend
developmental malformation found within 7 days after birth. Malformations were classified according to ICD-9 (International Classification of Disease-9). During the 15year period 1979- 1993, congenital malformations were observed in 2085 babies out of the 138544 newborn babies including stillbirths after 16 weeks gestation at 11 hospitals (10 hospitals since 198 1 and 8 since July 1989). Seventy-eight percent of the pregnant women were from the districts of Metropolitan Tokyo (North-west 35.4%, West 28.3%, Center 7.7% and South 6.3%), 8.7% from the suburbs of Tokyo, 11.4% from the neighboring districts and 2% were from other prefectures. TMH monitoring is a hospital-based system covering 7-8% of the total births in Tokyo, that is 55 655 (8.0%) births among 691078 total births in Tokyo in 1979-1983, 49079 (8.0%) among 612005 total births in 1984-1988 and 33810 (6.6%) among 5 12 945 total births in 1989- 1993. The number of births has gradually decreased in TMH as well as in all of Japan. Baseline rates are fundamental to the detection of increased rates of specific malformations. In the TMH monitoring system, a total of 104734 births including stillbirths after 16 weeks gestation have been accumulated during the IO-year period I979- 1988, therefore prevalence rates of 66 malformations have been calculated as the baseline markers [4]. These values have been used as baseline rates in TMH in this paper. The data were divided into three groups: 1979-1983. 19844 1988 and 1989-1993. The trend of prevalence of congenital malformations was statistically investigated. Multiple malforma-
K. Kate, K. Fujiki/Brain
231
& Development 1996; 18: 230-23-Z
up in 198 1 and covers one half of all births (40 000 births annually) in that prefecture. All live births and stillbirths are screened for 44 marker malformations found within 7 days after birth. The ascertainment ratio for each marker malformation was estimated and respected, and incidences adjusted by each ascertainment ratio were presented. Some of the prevalence rates per 10000 births are: anencephaly 4.8, total cleft lip 14.9 (corresponds to cleft lip and cleft palate with cleft lip in Table 2 of this paper), anorectal malformation 5.6, and Down syndrome 8.3 [6]. These values are also useful as standard background data for our hospital-based monitoring system. The prevalence of each malformation in TMH was compared with that in KAMP and JAMW. The prevalence rate of anencephaly in TMH (7.29 per 10000 births) was significantly higher than in KAMP (4.8) and JAMW (5.8, 1987-1991). The prevalence of Down syndrome was also significantly higher at 10.54 per 10000 births in TMH as compared to 8.3 in KAMP and 5.14 (1978-1991) in JAMW. The reasons for these differences were analyzed. In TMH, highrisk pregnancies from neighboring hospitals are brought in. The incidence rate of anencephaly in these pregnant women from neighboring hospitals was 2.1% (l/48), which was 1.75 times (statistically not significant) higher than the I .2% (117/9419) of the local women in 1981-1983; 3.9% (9/228) vs. 2.0% (173/8528) in 1985- 1987 which was I .95 times (P < 0.05); and 4.6% (28/605) vs. 1.7% (109/6565) in 199 I - 1993, which is 2.7 times (P < 0.01) higher than in the local women. This may be one of the reasons for the higher prevalence rates in TMH compared with KAMP and JAMW. Another reason for the high incidence of anencephaly in TMH was the inclusion of stillbirths from 16 weeks gestation onward in the TMH study compared to 22 or 24 weeks in KAMP and JAMW. Also, it was recognized that the age distribution of the pregnant women in TMH was wider than that nationwide. This will be one of the causes for having babies with a high risk of Down syndrome [7]. The prevalence of malformations in the heart and circulatory system, as shown in Table 2, gradually increased to 38.6, 63.2 and 74.8 per 10000 births in 1979-1983, 1984-1988 and 19891993, respectively. As there is no information on the heart and circulatory system in KAMP and JAMW, the data could not be compared: however. it is considered that this increase is due to
tions were divided into each system and recorded. Therefore, the total number of anomalies was 2828 for 2085 malformed babies.
3. RESULTS The base data obtained during 1979-1993 are summarized in Table 1. Among 138 544 newborn babies, the rate of stillbirths was 12.9 per 1000 births. The overall prevalence rate of malformations was IS%, 1.62% in males and 1.37% in females (P < 0.01). The prevalence of malformations showed practically no secular changes in total births including stillbirths during the 15 years monitored. The prevalence in each system and the selected malformations are shown in Table 2. Comparison of the three groups, the periods 1979-1983, 1984-1988 and 1989-1993, showed practically no secular change in the prevalence of each malformation during the 15 years monitored except for the heart and circulatory system.
4. DISCUSSION The frequency of malformed babies was 1.4% in 1979-1983, 1.6% in 1984-1988, and 1.6% in 1989-1993 as shown in Table 1. There was no secular change in the frequency of malformed babies with congenital malformations. According to the report of the Japan Association for Maternal Welfare (JAMW) Monitoring System, which is also a hospital-based monitoring system, the frequency of malformed babies increased slightly from 0.7% (731/106081) in 1972 to 1.0% (1156/114785) in 1991 [5]. Hydrocephaly increased from 1.32 per 10000 births in 1972 to 7.75 per 10000 births in 1991, and cleft palate with cleft lip also increased from 7.73 per 10000 births in 1972 to 8.89 per 10000 in 1991. Anencephaly decreased from 8.39 per 10000 births in 1984 to 4.70 per 10 000 births in 1991. Down syndrome increased from 2.77 per 10000 in 1978 to 7.61 per 10000 births in 1989 and decreased to 5.31 per 10000 births in 1991. The Kanagawa Birth Defects Monitoring Program (KAMP) in Kanagawa prefecture is a population-based monitoring system set
Table I Summary of the base data for the present study, 1979- 1993 1979-1983 Births Total births Male Female Intersex Unknown Live births Male Female Intersex Stillbirths Male Female Intersex Unknown
55655 28 674 26 892 3 87 54 809 28 222 26587 0 846 452 305 2 87
1984-1988 Anom.
Rate
775 420 352 2 1 711 382 329 0 64 38 23 2
I
1.39
1.46 1.31 66.67 1.15 I .30 1.35 1.24 7.57 8.41 7.54 100.00 1.15
1989-1993
Births
Anom.
49 079 25 043 23 962
778 427 348
Rate
I
I
73 48 485 24718 23 767 0 594 325 195 1 73
2 720 396 324 0 58 31 24 1 2
1.59 I .71
Births
All births Anom.
Rate
I .36
33 810 17344 16407 1 58 33 464 17 186 16277
I
I
9.76 9.54 12.31 100.00 2.74
346 158 130 0 58
39 23 13 0 3
1.45 100.00 2.74
1.48 1.60
532 304 224
I 3 493 281 211
1.57 I .75 1.37 100.00 5.17 I .47 1.64 I .30 100.00 11.27 14.56 10.00 5.17
Births I38 544 71061 67261 5 218 136758 70 126 66631 1 1786 935 630 3 21x
Anom.
Rate
2085 1151 924 4 6 1924 I059 864
I 161 92 60 3 6
I .50 1.62 1.37 80.00 2.75 1.41 1.51 I .30 ioo.00 9.01 9.84 9.52
100.00 2.75
232
K. Kato, K. Fujiki/Brain
Table 2 The number of anomalous cases and the prevalence Year
& Development
rate per 10000 births
ICD code
Baseline
740-742 740.0 741 742.0 742.1 742.2
104734 14.9 7.2 2.5 1.0 1.1 0.7
742.3 743 143 743.2 743.4 744 744.0
1979- 1983 Number
All births Nervous system Anencephaly Spina bifida Cranioschisis Microcephaly Holoprosencephaly, arhinencephalia or hypoplasia of cerebrum Congenital hydrocephaly Eye Anophthalmus or microphthalmus Buphthalmus Anomalies of iris Ear, face and neck Atresia or stenosis of auditory canal with or without ear Microtia or hypoplastic ear Heart and circulatory system Transposition of great vessels Tetralogy of Fallot Ventricular septal defect Atria1 septal defect Endocardial cushion defect Hypoplastic left heart syndrome Coarctation of aorta or interruption of aortic arch Pulmonary stenosis Respiratory system Malformed nose Aplasia, atresia or stenosis of bronchus and trachea Aplasia or hypoplasia of lung Digestive system Cleft palate Cleft lip Cleft palate with cleft lip Trachea-esophageal fistula or esophageal atresia Atresia or stenosis of small intestine Anal agenesis, anal atresia or anorectal stenosis Genital system Epispadias Hypospadias Intersex, hermaphroditism Urinary system Renal aplasia or hypoplasia Hydronephrosis, ureteral stenosis Horseshoe kidney, other anomalies of kidney Exstrophy of bladder Musculoskeletal system Polydactyly Syndactyly Polydactyly with syndactyly Upper limb reduction defects Lower limb reduction defects Upper and lower limb reduction defects Cleft hand
1996; 18: 230-233
55 655 81 39 13 3 7 5
1.9 3.2 I .o 0.3 0.2 18.9 2.4
744.2 745-747 745.1 745.2 745.4 745.5 745.6 746.7 747. I 747.3 748 748.1 748.3
1984-1988 Rate
Number
14.55 7.01 2.34 0.54 1.26 0.90
49079 75 36 13 7 5 2
10 I2 6 I 1 104 I6
1.80 2.16 1.08 0.18 0.18 18.69 2.87
2.8 50.1 1.1 1.2 16.4 1.3 0.8 0.6 0.9
16 215 6 5 64 4 2 2 3
1.0 3.3 1.0 0.7
1989-1993 Rate
Number
15.28 7.34 2.65 1.43 I .02 0.41
33810 46 26 10 3 2 1
IO 21 4 2 1 94 9
2.04 4.28 0.82 0.4 1 0.20 19.15 1.83
2.87 38.63 1.08 0.90 11.50 0.72 0.36 0.36 0.54
13 310 5 8 108 IO 6 4 6
3 19 7 2
0.54 3.41 I .26 0.36
1.4 35.8 6.6 5.4 7.9 2.1
8 196 33 29 45 9
751.lg
1.8
75 1.2c
Total Rate
Number
Rate
13.61 7.69 2.96 0.89 0.59 0.30
138544 202 101 36 I3 I4 8
14.58 7.29 2.60 0.94 I.01 0.58
4 11 3 0 I 47 11
1.18 3.25 0.89 0.00 0.30 13.90 3.25
24 44 I3 3 3 245 36
I .73 3.18 0.94 0.22 0.22 17.68 2.60
2.65 63.16 I .02 1.63 22.01 2.04 1.22 0.82 I .22
6 253 9 14 114 21 4 5 4
1.77 74.83 2.66 4.14 33.72 6.21 1.18 1.48 1.18
35 778 20 27 286 35 I2 II 13
2.53 56.16 I .44 1.95 20.64 2.53 0.87 0.79 0.94
7 16 3 5
1.43 3.26 0.61 1.02
16 13 0 4
4.73 3.85 0.00 1.18
26 48 10 11
1.88 3.46 0.72 0.79
1.44 35.22 5.93 5.21 8.09 1.62
7 179 36 28 38 13
1.43 36.41 1.34 5.71 7.74 2.65
8 112 16 14 27 5
2.37 33.13 4.73 4.14 7.99 1.48
23 487 85 71 I IO 27
1.66 35.15 6.14 5.12 7.94 I .95
9
1.62
10
2.04
7
2.07
26
I .88
5.4
31
5.57
26
5.30
20
5.92
77
5.56
752 752.6 752.6 752.7 753 753.0 753.2 753.3
8.3 0.2 2.7 1.0 4.1 0.7 0.9 0.4
47 1 10 6 18 4 1 1
8.44 0.18 1.80 1.08 3.23 0.72 0.18 0.18
40 I 18 4 25 3 8 3
8.15 0.20 3.67 0.82 5.09 0.61 1.63 0.61
29 0 12 5 12 3 4 0
8.58 0.00 3.55 1.48 3.55 0.89 1.18 0.00
II6 2 40 15 55 10 13 4
8.37 0.14 2.89 1.08 3.97 0.72 0.94 0.29
753.5 754-756 755.0 755.1 755 755.2 755.3 755 755.5
0.9 50.3 9.6 7.0 5.3 4.2 1.1 0.9 0.6
7 292 54 43 28 28 11 7 3
1.26 52.47 9.70 7.73 5.03 5.03 1.98 1.26 0.54
2 235 47 30 27 16 0 2 3
0.41 47.88 9.58 6.1 I 5.50 3.26 0.00 0.41 0.61
0 158 28 16 12 12 5 3 0
0.00 46.73 8.28 4.73 3.55 3.55 1.48 0.89 0.00
9 685 129 89 67 56 16 I2 6
0.65 49.44 9.31 6.42 4.84 4.04 1.15 0.87 0.43
748.5 749-75 1 749.0 749.1 749.2 750.3a
K. Kato, K. Fujiki/
Brain & Development
1996; 18: 230-233
233
Table 2 (continued Year
ICD code
Baseline
1979-1983 Number
Cleft foot Defects of diaphragm Diaphragmatic hernia Abdominal wall defects Gastroschisia Exomphaloa Integumentary system Ichthyosis congenita Aplasia cutis Epidermolysis bullosa hereditaria Chromosomal anomalies Down syndrome Patau syndrome Edwards syndrome Other and unspecified congenital anomalies Ring constriction syndrome Double monsters Acardius acephalus Cyclopia Total
755.6 156.6 756.6 756.1 756.7 756.7 757 757.1 757.3 751.3 758 758.0 758.1 758.2 759
0.4 0.4 1.5 0.3 0.9 2.3 6.2 0.3 0.5 0.3 13.3 10.6 0.3 I .4 6.0
755 759.4 759.8 759.8
0.5 0.3 0.1 0.2 201.2
the recent
diagnosis
progress
of
prenatal
in
life.
ACKNOWLEDGEMENTS This study was partially grant from the Japan Ministry of Health and Welfare.
1 2 8
0.18 0.36
1
0.18 0.90 2.52 6.29 0.54 0.36 0.36 Il.86 IO.24 0.18 I .08 6.83
5 14 35 3 2 2 66 57
I 6 38
early
These facts show that the specificity should be taken into consideration for monitoring.
intrauterine
3 2 1 1 1057
stages
1984-198X Rate
of 3.
by a
4.
5.
REFERENCES 6. Kondo K, Kato K, Henmi 1, Kurosu T. Birth defects monitoring in the Tokyo metropolitatl hospitals, 5 years report, 1978- 1982 (in Japanese). Tokyo: Tokyo Metropolitan Institute for Neuroscience, 1984. Kato K, Yokochi M, Yoshimura K, Fujiki K, Kurosu T, Shimamura M. Birth defects monitoring in Tokyo metropolitan hospitals, 10 years
I 73 54 2 9 25
0.54 0.36 0.18 0.18 189.92
7.
2 1 0
1 -
1989-1993 Rate
3 2 8 2 4 10 30 0 3
1.44
of TMH
supported
Number
I050
0.6 I 0.4 I I .63 0.4 I 0.82 2.04 6.1 I
Total Rate
Number
0.41 1.83 5.09
I4 3 2 0 53 35 I 9 26
0.30 0.30 2.96 0.00 I .4x 2.96 -1.13 0.89 0.59 0.00 15.68 IO.35 0.30 2.66 7.69
0.41 0.20 0.00 0.20 213.94
2 0 I I 721
0.59 0.00 0.30 0.30 213.25
0.00 0.61 0.20 14.87
I I .oo
I I I0
0 5 IO
Number
s s 36 3 I4 34 79 6 7
3 192 146 4 24 x9 7 3 2 3 2828
Rate 0.36 0.36 1.88
0.22 I.01 2.45 5.70 0.13 0.5 I
0.22 13.86 IO.54 0.29 I .73 6.32 0.5 1 0.22 0. I4 0.22 204. I2
report, /979-198X (in Japanese). Tokyo: Tokyo Metropolitan Institute for Neuroscience, 1990. Kato K. Annual trends in incidence of congenital anomalies in Tokyo metropolitan hospitals (in Japanese). Nihon Koshu Ei.rei Gakkai Zu~hi (Tokyoi 1995; 42: 129-38. Kato K. Frequencies of congenital anomalies - baseline rate from monitoring system in the Tokyo metropolitan hospitals (in Japanese). Shusanki Igaku (Tokyol 1994; 24: 569-15. Maruyama M. Sumiyoshi Y, Seida A. eda. Tokyo: Surveillance of congenital anomalies, 1972- 199/ (in Japanese). Tokyo: Japan Association for Maternal Welfare. 1993. Kuroki Y. Imaizumi K, Konishi H. The incidences of naturally occurring birth defects in the neonates based on the data obtained in the Kanagawa Birth Defects Monitoring Program (KAMP) (abstract). Jpn .I Hum Genet f Tokyo) 1995: 40: 92. Kato K, Fujiki K. A study of congenital malformations in Tokyo metropolitan hospitals for 15 years (absract). XXXV Annual Meeting of the Japanese Teratology Society. Co?i,~ Anom 1995; 35: 39 I.
Brain & Development
Q
1996; 18: 230-233
Short communication
Incidence of congenital malformations in Tokyo Metropolitan Hospitals, 1979- 1993 Kyoko a Department
Kato a,* , Keiko Fujiki
b
ofNeurology,Tokyo
Metropolitan Institutefor Neuroscience, 2-6 Musashidai, Fuchu-city, Tokyo 183, Japan b Department of Ophthalmology, Juntendo Unicersity School of Medicine, Tokyo 113, Japan Received 3 1 March 1995; accepted
I8 September 1995
Congenital malformations in all babies delivered at 11 Tokyo Metropolitan Hospitals (TMH) (8 hospitals since July 1989) for 15 years, January 1979 to December 1993, were monitored. Congenital malformations found within 7 days after birth were observed in 2085 babies (1.5%) of 138544 births including stillbirths after 16 weeks gestation. The prevalence rates of selected malformations were calculated and compared in the 5-year periods of 1979-1983, 1984-1988 and 1989-1993. There was no typical secular trend in prevalence rates of malformations except for the heart and circulatory system, which showed an increase because of the recent progress in prenatal diagnosis of these malformations. The specificity of the TMH Monitoring System is also discussed. Keywords;
Monitoring;
Congenital
malformation;
Tokyo Metropolitan
Hospitals;
1. INTRODUCTION A birth defect monitoring program is one of the most important strategies for detecting the emergence of new mutations, teratogens or new abnormalities in newborn babies. It can also be used in evaluating any possible effect of preventive measures against the occurrence of congenital malformations in general. For these purposes, congenital malformations have been monitored in all babies delivered at the Tokyo Metropolitan Hospitals (TMH) since April 1978 [l-3]. In the present study, a secular trend was analyzed every 5 years of prevalence of congenital malformations in all babies delivered in TMH during the period 1979- 1993.
2. SUBJECTS
AND METHODS
The data were collected by visiting the hospitals every l-2 months since the TMH monitoring system was started in April 1978. The gestational age (weeks), birth weight, maternal age at birth, congenital malformation of newborn babies and other relevant information were registered. Congenital malformation was defined in this study as a gross physical or anatomical
* Corresponding
author. Fax: (81) (423) 21-8678.
0387-7604/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0387-7604(95)00113-l
Prevalence
rate; Secular trend
developmental malformation found within 7 days after birth. Malformations were classified according to ICD-9 (International Classification of Disease-9). During the 15year period 1979- 1993, congenital malformations were observed in 2085 babies out of the 138544 newborn babies including stillbirths after 16 weeks gestation at 11 hospitals (10 hospitals since 198 1 and 8 since July 1989). Seventy-eight percent of the pregnant women were from the districts of Metropolitan Tokyo (North-west 35.4%, West 28.3%, Center 7.7% and South 6.3%), 8.7% from the suburbs of Tokyo, 11.4% from the neighboring districts and 2% were from other prefectures. TMH monitoring is a hospital-based system covering 7-8% of the total births in Tokyo, that is 55 655 (8.0%) births among 691078 total births in Tokyo in 1979-1983, 49079 (8.0%) among 612005 total births in 1984-1988 and 33810 (6.6%) among 5 12 945 total births in 1989- 1993. The number of births has gradually decreased in TMH as well as in all of Japan. Baseline rates are fundamental to the detection of increased rates of specific malformations. In the TMH monitoring system, a total of 104734 births including stillbirths after 16 weeks gestation have been accumulated during the IO-year period I979- 1988, therefore prevalence rates of 66 malformations have been calculated as the baseline markers [4]. These values have been used as baseline rates in TMH in this paper. The data were divided into three groups: 1979-1983. 19844 1988 and 1989-1993. The trend of prevalence of congenital malformations was statistically investigated. Multiple malforma-
K. Kate, K. Fujiki/Brain
231
& Development 1996; 18: 230-23-Z
up in 198 1 and covers one half of all births (40 000 births annually) in that prefecture. All live births and stillbirths are screened for 44 marker malformations found within 7 days after birth. The ascertainment ratio for each marker malformation was estimated and respected, and incidences adjusted by each ascertainment ratio were presented. Some of the prevalence rates per 10000 births are: anencephaly 4.8, total cleft lip 14.9 (corresponds to cleft lip and cleft palate with cleft lip in Table 2 of this paper), anorectal malformation 5.6, and Down syndrome 8.3 [6]. These values are also useful as standard background data for our hospital-based monitoring system. The prevalence of each malformation in TMH was compared with that in KAMP and JAMW. The prevalence rate of anencephaly in TMH (7.29 per 10000 births) was significantly higher than in KAMP (4.8) and JAMW (5.8, 1987-1991). The prevalence of Down syndrome was also significantly higher at 10.54 per 10000 births in TMH as compared to 8.3 in KAMP and 5.14 (1978-1991) in JAMW. The reasons for these differences were analyzed. In TMH, highrisk pregnancies from neighboring hospitals are brought in. The incidence rate of anencephaly in these pregnant women from neighboring hospitals was 2.1% (l/48), which was 1.75 times (statistically not significant) higher than the I .2% (117/9419) of the local women in 1981-1983; 3.9% (9/228) vs. 2.0% (173/8528) in 1985- 1987 which was I .95 times (P < 0.05); and 4.6% (28/605) vs. 1.7% (109/6565) in 199 I - 1993, which is 2.7 times (P < 0.01) higher than in the local women. This may be one of the reasons for the higher prevalence rates in TMH compared with KAMP and JAMW. Another reason for the high incidence of anencephaly in TMH was the inclusion of stillbirths from 16 weeks gestation onward in the TMH study compared to 22 or 24 weeks in KAMP and JAMW. Also, it was recognized that the age distribution of the pregnant women in TMH was wider than that nationwide. This will be one of the causes for having babies with a high risk of Down syndrome [7]. The prevalence of malformations in the heart and circulatory system, as shown in Table 2, gradually increased to 38.6, 63.2 and 74.8 per 10000 births in 1979-1983, 1984-1988 and 19891993, respectively. As there is no information on the heart and circulatory system in KAMP and JAMW, the data could not be compared: however. it is considered that this increase is due to
tions were divided into each system and recorded. Therefore, the total number of anomalies was 2828 for 2085 malformed babies.
3. RESULTS The base data obtained during 1979-1993 are summarized in Table 1. Among 138 544 newborn babies, the rate of stillbirths was 12.9 per 1000 births. The overall prevalence rate of malformations was IS%, 1.62% in males and 1.37% in females (P < 0.01). The prevalence of malformations showed practically no secular changes in total births including stillbirths during the 15 years monitored. The prevalence in each system and the selected malformations are shown in Table 2. Comparison of the three groups, the periods 1979-1983, 1984-1988 and 1989-1993, showed practically no secular change in the prevalence of each malformation during the 15 years monitored except for the heart and circulatory system.
4. DISCUSSION The frequency of malformed babies was 1.4% in 1979-1983, 1.6% in 1984-1988, and 1.6% in 1989-1993 as shown in Table 1. There was no secular change in the frequency of malformed babies with congenital malformations. According to the report of the Japan Association for Maternal Welfare (JAMW) Monitoring System, which is also a hospital-based monitoring system, the frequency of malformed babies increased slightly from 0.7% (731/106081) in 1972 to 1.0% (1156/114785) in 1991 [5]. Hydrocephaly increased from 1.32 per 10000 births in 1972 to 7.75 per 10000 births in 1991, and cleft palate with cleft lip also increased from 7.73 per 10000 births in 1972 to 8.89 per 10000 in 1991. Anencephaly decreased from 8.39 per 10000 births in 1984 to 4.70 per 10 000 births in 1991. Down syndrome increased from 2.77 per 10000 in 1978 to 7.61 per 10000 births in 1989 and decreased to 5.31 per 10000 births in 1991. The Kanagawa Birth Defects Monitoring Program (KAMP) in Kanagawa prefecture is a population-based monitoring system set
Table I Summary of the base data for the present study, 1979- 1993 1979-1983 Births Total births Male Female Intersex Unknown Live births Male Female Intersex Stillbirths Male Female Intersex Unknown
55655 28 674 26 892 3 87 54 809 28 222 26587 0 846 452 305 2 87
1984-1988 Anom.
Rate
775 420 352 2 1 711 382 329 0 64 38 23 2
I
1.39
1.46 1.31 66.67 1.15 I .30 1.35 1.24 7.57 8.41 7.54 100.00 1.15
1989-1993
Births
Anom.
49 079 25 043 23 962
778 427 348
Rate
I
I
73 48 485 24718 23 767 0 594 325 195 1 73
2 720 396 324 0 58 31 24 1 2
1.59 I .71
Births
All births Anom.
Rate
I .36
33 810 17344 16407 1 58 33 464 17 186 16277
I
I
9.76 9.54 12.31 100.00 2.74
346 158 130 0 58
39 23 13 0 3
1.45 100.00 2.74
1.48 1.60
532 304 224
I 3 493 281 211
1.57 I .75 1.37 100.00 5.17 I .47 1.64 I .30 100.00 11.27 14.56 10.00 5.17
Births I38 544 71061 67261 5 218 136758 70 126 66631 1 1786 935 630 3 21x
Anom.
Rate
2085 1151 924 4 6 1924 I059 864
I 161 92 60 3 6
I .50 1.62 1.37 80.00 2.75 1.41 1.51 I .30 ioo.00 9.01 9.84 9.52
100.00 2.75
232
K. Kato, K. Fujiki/Brain
Table 2 The number of anomalous cases and the prevalence Year
& Development
rate per 10000 births
ICD code
Baseline
740-742 740.0 741 742.0 742.1 742.2
104734 14.9 7.2 2.5 1.0 1.1 0.7
742.3 743 143 743.2 743.4 744 744.0
1979- 1983 Number
All births Nervous system Anencephaly Spina bifida Cranioschisis Microcephaly Holoprosencephaly, arhinencephalia or hypoplasia of cerebrum Congenital hydrocephaly Eye Anophthalmus or microphthalmus Buphthalmus Anomalies of iris Ear, face and neck Atresia or stenosis of auditory canal with or without ear Microtia or hypoplastic ear Heart and circulatory system Transposition of great vessels Tetralogy of Fallot Ventricular septal defect Atria1 septal defect Endocardial cushion defect Hypoplastic left heart syndrome Coarctation of aorta or interruption of aortic arch Pulmonary stenosis Respiratory system Malformed nose Aplasia, atresia or stenosis of bronchus and trachea Aplasia or hypoplasia of lung Digestive system Cleft palate Cleft lip Cleft palate with cleft lip Trachea-esophageal fistula or esophageal atresia Atresia or stenosis of small intestine Anal agenesis, anal atresia or anorectal stenosis Genital system Epispadias Hypospadias Intersex, hermaphroditism Urinary system Renal aplasia or hypoplasia Hydronephrosis, ureteral stenosis Horseshoe kidney, other anomalies of kidney Exstrophy of bladder Musculoskeletal system Polydactyly Syndactyly Polydactyly with syndactyly Upper limb reduction defects Lower limb reduction defects Upper and lower limb reduction defects Cleft hand
1996; 18: 230-233
55 655 81 39 13 3 7 5
1.9 3.2 I .o 0.3 0.2 18.9 2.4
744.2 745-747 745.1 745.2 745.4 745.5 745.6 746.7 747. I 747.3 748 748.1 748.3
1984-1988 Rate
Number
14.55 7.01 2.34 0.54 1.26 0.90
49079 75 36 13 7 5 2
10 I2 6 I 1 104 I6
1.80 2.16 1.08 0.18 0.18 18.69 2.87
2.8 50.1 1.1 1.2 16.4 1.3 0.8 0.6 0.9
16 215 6 5 64 4 2 2 3
1.0 3.3 1.0 0.7
1989-1993 Rate
Number
15.28 7.34 2.65 1.43 I .02 0.41
33810 46 26 10 3 2 1
IO 21 4 2 1 94 9
2.04 4.28 0.82 0.4 1 0.20 19.15 1.83
2.87 38.63 1.08 0.90 11.50 0.72 0.36 0.36 0.54
13 310 5 8 108 IO 6 4 6
3 19 7 2
0.54 3.41 I .26 0.36
1.4 35.8 6.6 5.4 7.9 2.1
8 196 33 29 45 9
751.lg
1.8
75 1.2c
Total Rate
Number
Rate
13.61 7.69 2.96 0.89 0.59 0.30
138544 202 101 36 I3 I4 8
14.58 7.29 2.60 0.94 I.01 0.58
4 11 3 0 I 47 11
1.18 3.25 0.89 0.00 0.30 13.90 3.25
24 44 I3 3 3 245 36
I .73 3.18 0.94 0.22 0.22 17.68 2.60
2.65 63.16 I .02 1.63 22.01 2.04 1.22 0.82 I .22
6 253 9 14 114 21 4 5 4
1.77 74.83 2.66 4.14 33.72 6.21 1.18 1.48 1.18
35 778 20 27 286 35 I2 II 13
2.53 56.16 I .44 1.95 20.64 2.53 0.87 0.79 0.94
7 16 3 5
1.43 3.26 0.61 1.02
16 13 0 4
4.73 3.85 0.00 1.18
26 48 10 11
1.88 3.46 0.72 0.79
1.44 35.22 5.93 5.21 8.09 1.62
7 179 36 28 38 13
1.43 36.41 1.34 5.71 7.74 2.65
8 112 16 14 27 5
2.37 33.13 4.73 4.14 7.99 1.48
23 487 85 71 I IO 27
1.66 35.15 6.14 5.12 7.94 I .95
9
1.62
10
2.04
7
2.07
26
I .88
5.4
31
5.57
26
5.30
20
5.92
77
5.56
752 752.6 752.6 752.7 753 753.0 753.2 753.3
8.3 0.2 2.7 1.0 4.1 0.7 0.9 0.4
47 1 10 6 18 4 1 1
8.44 0.18 1.80 1.08 3.23 0.72 0.18 0.18
40 I 18 4 25 3 8 3
8.15 0.20 3.67 0.82 5.09 0.61 1.63 0.61
29 0 12 5 12 3 4 0
8.58 0.00 3.55 1.48 3.55 0.89 1.18 0.00
II6 2 40 15 55 10 13 4
8.37 0.14 2.89 1.08 3.97 0.72 0.94 0.29
753.5 754-756 755.0 755.1 755 755.2 755.3 755 755.5
0.9 50.3 9.6 7.0 5.3 4.2 1.1 0.9 0.6
7 292 54 43 28 28 11 7 3
1.26 52.47 9.70 7.73 5.03 5.03 1.98 1.26 0.54
2 235 47 30 27 16 0 2 3
0.41 47.88 9.58 6.1 I 5.50 3.26 0.00 0.41 0.61
0 158 28 16 12 12 5 3 0
0.00 46.73 8.28 4.73 3.55 3.55 1.48 0.89 0.00
9 685 129 89 67 56 16 I2 6
0.65 49.44 9.31 6.42 4.84 4.04 1.15 0.87 0.43
748.5 749-75 1 749.0 749.1 749.2 750.3a
K. Kato, K. Fujiki/
Brain & Development
1996; 18: 230-233
233
Table 2 (continued Year
ICD code
Baseline
1979-1983 Number
Cleft foot Defects of diaphragm Diaphragmatic hernia Abdominal wall defects Gastroschisia Exomphaloa Integumentary system Ichthyosis congenita Aplasia cutis Epidermolysis bullosa hereditaria Chromosomal anomalies Down syndrome Patau syndrome Edwards syndrome Other and unspecified congenital anomalies Ring constriction syndrome Double monsters Acardius acephalus Cyclopia Total
755.6 156.6 756.6 756.1 756.7 756.7 757 757.1 757.3 751.3 758 758.0 758.1 758.2 759
0.4 0.4 1.5 0.3 0.9 2.3 6.2 0.3 0.5 0.3 13.3 10.6 0.3 I .4 6.0
755 759.4 759.8 759.8
0.5 0.3 0.1 0.2 201.2
the recent
diagnosis
progress
of
prenatal
in
life.
ACKNOWLEDGEMENTS This study was partially grant from the Japan Ministry of Health and Welfare.
1 2 8
0.18 0.36
1
0.18 0.90 2.52 6.29 0.54 0.36 0.36 Il.86 IO.24 0.18 I .08 6.83
5 14 35 3 2 2 66 57
I 6 38
early
These facts show that the specificity should be taken into consideration for monitoring.
intrauterine
3 2 1 1 1057
stages
1984-198X Rate
of 3.
by a
4.
5.
REFERENCES 6. Kondo K, Kato K, Henmi 1, Kurosu T. Birth defects monitoring in the Tokyo metropolitatl hospitals, 5 years report, 1978- 1982 (in Japanese). Tokyo: Tokyo Metropolitan Institute for Neuroscience, 1984. Kato K, Yokochi M, Yoshimura K, Fujiki K, Kurosu T, Shimamura M. Birth defects monitoring in Tokyo metropolitan hospitals, 10 years
I 73 54 2 9 25
0.54 0.36 0.18 0.18 189.92
7.
2 1 0
1 -
1989-1993 Rate
3 2 8 2 4 10 30 0 3
1.44
of TMH
supported
Number
I050
0.6 I 0.4 I I .63 0.4 I 0.82 2.04 6.1 I
Total Rate
Number
0.41 1.83 5.09
I4 3 2 0 53 35 I 9 26
0.30 0.30 2.96 0.00 I .4x 2.96 -1.13 0.89 0.59 0.00 15.68 IO.35 0.30 2.66 7.69
0.41 0.20 0.00 0.20 213.94
2 0 I I 721
0.59 0.00 0.30 0.30 213.25
0.00 0.61 0.20 14.87
I I .oo
I I I0
0 5 IO
Number
s s 36 3 I4 34 79 6 7
3 192 146 4 24 x9 7 3 2 3 2828
Rate 0.36 0.36 1.88
0.22 I.01 2.45 5.70 0.13 0.5 I
0.22 13.86 IO.54 0.29 I .73 6.32 0.5 1 0.22 0. I4 0.22 204. I2
report, /979-198X (in Japanese). Tokyo: Tokyo Metropolitan Institute for Neuroscience, 1990. Kato K. Annual trends in incidence of congenital anomalies in Tokyo metropolitan hospitals (in Japanese). Nihon Koshu Ei.rei Gakkai Zu~hi (Tokyoi 1995; 42: 129-38. Kato K. Frequencies of congenital anomalies - baseline rate from monitoring system in the Tokyo metropolitan hospitals (in Japanese). Shusanki Igaku (Tokyol 1994; 24: 569-15. Maruyama M. Sumiyoshi Y, Seida A. eda. Tokyo: Surveillance of congenital anomalies, 1972- 199/ (in Japanese). Tokyo: Japan Association for Maternal Welfare. 1993. Kuroki Y. Imaizumi K, Konishi H. The incidences of naturally occurring birth defects in the neonates based on the data obtained in the Kanagawa Birth Defects Monitoring Program (KAMP) (abstract). Jpn .I Hum Genet f Tokyo) 1995: 40: 92. Kato K, Fujiki K. A study of congenital malformations in Tokyo metropolitan hospitals for 15 years (absract). XXXV Annual Meeting of the Japanese Teratology Society. Co?i,~ Anom 1995; 35: 39 I.