Abstract
The Fukushima Daiichi Nuclear Disaster (FDND) occurred in 2011, which occurred after the Great East Japan Earthquake. However, how the incidence of radiation‐induced malformations in Fukushima has been affected by FDND remains to be elucidated. To address this, we analyzed birth data from Fukushima and other areas in Japan from the International Clearinghouse for Birth Defects Surveillance and Research Japan Center, including information on birth defects between January 2010 and December 2022. Among the registered birth defects, microcephaly, microphthalmia, and neural tube defects were classified as radiation‐induced malformations. Our study included 90 433 births in Fukushima, accounting for 52.6% of all births. Among these, birth defects were observed in 1376 (1.52%) births, of which 28 (0.031%) were diagnosed with radiation‐induced malformations. With regard to other areas in Japan, 1 323 391 births, which accounted for 10.9% of all births, were registered; births with birth defects and radiation‐induced malformations were observed in 37 490 (3.67%) and 889 (0.067%), respectively. Because sampling bias was suspected, we compared the rates of radiation‐induced malformations in Fukushima and other areas in Japan by adjusting the incidence in Fukushima with the incidences of ventricular septal defects in both areas. However, there was no statistically significant difference between them. Our results, which covered the largest number of births in Fukushima, did not find a significant increase in the incidence of radiation‐induced malformations in Fukushima since FDND.
Keywords: radiation‐induced congenital malformations, the Fukushima Daiichi Nuclear Disaster, the Great East Japan Earthquake, the International Clearinghouse for Birth Defects Surveillance and Research
1. INTRODUCTION
Nuclear power plant accidents are rare but serious disasters that have detrimental effects on health outcomes; some medical conditions occur directly from radiation exposure, while others arise from the secondary effects of these accidents. 1 Five nuclear power plant accidents occurred: Kyshtym (1957), Windscale Piles (1957), Three Mile Island (1979), Chernobyl (1986), and Fukushima (Japan, 2011). 1 The Fukushima Daiichi Nuclear Disaster (FDND) was caused by the 2011 Great East Japan Earthquake and a subsequent tsunami, resulting in the release of radioactive contaminants.
Radiation exposures during pregnancy can negatively affect fetuses, and adverse outcomes include spontaneous pregnancy loss, fetal growth retardation, congenital birth defects, intellectual disabilities, and cancers. 2 , 3 , 4 Chernobyl nuclear power plant accidents have been reported to cause a higher incidence of neural tube closure defects, microcephaly, and microphthalmia, especially in highly contaminated areas. 5 , 6 Although several reports have mentioned that perinatal outcomes have not worsened after the accidents, 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 there have been no reports focusing on the incidence of radiation‐induced malformations.
Therefore, we conducted this study with the aim to assess the incidence of radiation‐induced malformations in Fukushima using the International Clearinghouse for Birth Defects Surveillance and Research Japan Center (ICBDSR Japan Branch), which traced nearly half of the births in Fukushima 13 years after FDND.
2. MATERIALS AND METHODS
2.1. Data collection
The ICBDSR Japan Branch conducts statistical surveys of congenital malformations in Japan, and we obtained the birth data in the ICBDSR between January 1, 2010, and December 31, 2022, which totaled 90 433 and 1 323 391 births in Fukushima and other areas in Japan, respectively. Briefly, the ICBDSR Japan Branch was established in 1972 by the Japan Society for Maternal Protection and Obstetrics and Gynecology (now the Japan Society of Obstetricians and Gynecologists) to monitor congenital birth defects on a nationwide scale, and it has been conducting statistical surveys on congenital birth defects thenceforth. Diagnoses of congenital birth defects were made by attending obstetricians at collaborating institutions according to the 120 diagnoses listed in the ICBDSR survey form, which were sent to the ICBDSR Japan Branch. The survey collected information on neonates and their mothers. Neonatal information included diagnoses of congenital birth defects, birth month and year, gestational age at the time of delivery, birth weight, and birth outcomes (normal delivery, fetal distress, or stillbirth). Maternal information included clinical background, age, medical history, and obstetric history. Additionally, data regarding smoking history, alcohol consumption, oral medication use, and radiation exposure before 16 weeks of gestation were collected. The total number of deliveries in the collaborating institutions was also sent to the ICBDSR Japan Branch. The requirement for informed consent was waived in this study because of its size, which included over one hundred thousand participants annually. Obtaining informed consent is impractical, and including only those with consent may result in bias. We have provided details about the research on this website (https://icbdsr-j.jp/) to make it publicly available.
2.2. Diagnoses of congenital anomalies and radiation‐induced malformations
Among the diagnoses listed in the survey form, microcephaly, microphthalmia, and neural tube defects were used as indicators of radiation‐induced malformations. 6 , 16 Neural tube closure disorder was defined as a spinal meningocele and a herniated cerebral aneurysm. Although the ICBDSR did not provide strict criteria for the diagnosis of microcephaly, it was generally defined as a newborn head circumference measurement of less than −2 standard deviations. 17 Microphthalmia was diagnosed when the total axial length of the eyeball was <16 mm at birth. 18
2.3. Statistical analysis
Since sampling bias was suspected between the data obtained in Fukushima and other areas, and the data in Fukushima included a substantial portion of the target population, descriptive analysis was employed for the main analysis instead of the inferential statistical methods. We calculated the incidence of radiation‐induced malformations between Fukushima and other areas in Japan and compared them on a year‐by‐year basis. We calculated 95% confidence intervals of the percentages of incidence using the Wilson method. Moreover, we calculated 95% confidence intervals of the odds ratios of radiation‐induced malformations using the chi‐squared test. Given the possibility of sampling bias, we calculated adjusted incidences of radiation‐induced malformations in Fukushima using the incidences of ventricular septal defects (VSDs) in Fukushima and other areas. The adjustment was calculated using the following formula: (adjusted incidence of radiation‐induced malformations in Fukushima) = ([VSD incidence in other areas]/[VSD incidence in Fukushima]) × (incidence of radiation‐induced malformations in other areas).
Because this was an exploratory study, we did not conduct multiplicity adjustments. All statistical tests were two‐sided with a significance threshold of p < 0.05. These analyses were conducted using statistical models (version 0.14.2) and SciPy (version 1.14.0) packages in Python 3.12.4. 19 , 20
2.4. Ethical considerations
This study was conducted according to the principles of the Declaration of Helsinki. This study was approved by the Institutional Review Board of Yokohama City University School of Medicine (A140925013).
3. RESULTS
Between January 1, 2010, and December 31, 2022, 1 413 824 births were recorded in the ICBDSR, with 90 433 births in Fukushima and 1 323 391 births in other areas in Japan, which accounted for 52.8% and 10.9% of all births in Fukushima and other areas in Japan, respectively (Table 1). Survey rates in Fukushima increased markedly after FDND, whereas no significant changes were observed in the survey rates in other areas in Japan. Survey reports were collected from primary and tertiary centers in Fukushima. In contrast, a major part of the survey reports in the other areas came from secondary or tertiary centers (data not shown).
TABLE 1.
Number of births reported from collaborating institutions.
| Year | Fukushima | The other areas in Japan | ||||
|---|---|---|---|---|---|---|
| ICBDSR | Population survey | Percentage (%) | ICBDSR | Population survey | Percentage (%) | |
| 2010 | 560 | 16 169 | 3.46 | 90 522 | 1 055 136 | 8.58 |
| 2011 | 240 | 15 190 | 1.58 | 94 527 | 1 035 617 | 9.13 |
| 2012 | 7813 | 13 799 | 56.62 | 100 274 | 1 023 433 | 9.80 |
| 2013 | 10 258 | 14 476 | 70.86 | 100 923 | 1 015 341 | 9.94 |
| 2014 | 10 429 | 14 541 | 71.72 | 102 604 | 989 068 | 10.37 |
| 2015 | 9993 | 14 252 | 70.12 | 103 841 | 991 469 | 10.47 |
| 2016 | 9503 | 13 753 | 69.10 | 107 102 | 963 489 | 11.12 |
| 2017 | 8672 | 13 331 | 65.05 | 105 728 | 932 815 | 11.33 |
| 2018 | 8322 | 12 570 | 66.21 | 110 546 | 905 830 | 12.20 |
| 2019 | 7129 | 11 595 | 61.48 | 105 091 | 853 644 | 12.31 |
| 2020 | 6663 | 11 265 | 59.15 | 103 892 | 829 570 | 12.52 |
| 2021 | 5660 | 10 683 | 52.98 | 100 241 | 800 939 | 12.52 |
| 2022 | 5191 | 9804 | 52.95 | 98 100 | 760 955 | 12.89 |
| 2010–2022 | 90 433 | 171 428 | 52.75 | 1 323 391 | 12 157 306 | 10.89 |
Note: ICBDSR data account for 52.8% and 10.9% in Fukushima and the other areas in Japan, respectively.
Abbreviation: ICBDSR, The International Clearinghouse for Birth Defects Surveillance and Research Japan Center.
Given the discrepancies between the survey rates in Fukushima and those in other areas, we suspected sampling bias between these two populations. To assess this, we calculated the rates of newborns with congenital birth defects in these two populations. The rates in Fukushima were lower than those in the other areas (Table 2). We also compared the backgrounds of the survey data of the two populations (Table 3 and Figure S1). The multiple birth rate in the other areas outnumbered that in Fukushima, and oral medication use before 16 weeks of gestation was frequently observed in Fukushima. These results suggest potential biases, including sampling and confounding biases, with particular attention given to sampling bias in further analyses.
TABLE 2.
Number of newborns with congenital birth defects.
| Year | Fukushima | The other areas in Japan | ||||
|---|---|---|---|---|---|---|
| Number | Total | Percentage (%) | Number | Total | Percentage (%) | |
| 2010 | 33 | 560 | 5.89 | 2069 | 90 522 | 2.29 |
| 2011 | 17 | 240 | 7.08 | 2287 | 94 527 | 2.42 |
| 2012 | 135 | 7813 | 1.73 | 2389 | 100 274 | 2.38 |
| 2013 | 133 | 10 258 | 1.30 | 2509 | 100 923 | 2.49 |
| 2014 | 127 | 10 429 | 1.22 | 2667 | 102 604 | 2.60 |
| 2015 | 120 | 9993 | 1.20 | 2793 | 103 841 | 2.69 |
| 2016 | 115 | 9503 | 1.21 | 2910 | 107 102 | 2.72 |
| 2017 | 133 | 8672 | 1.53 | 3074 | 105 728 | 2.91 |
| 2018 | 134 | 8322 | 1.61 | 3308 | 110 546 | 2.99 |
| 2019 | 143 | 7129 | 2.01 | 3270 | 105 091 | 3.11 |
| 2020 | 103 | 6663 | 1.55 | 3375 | 103 892 | 3.25 |
| 2021 | 88 | 5660 | 1.55 | 3461 | 100 241 | 3.45 |
| 2022 | 95 | 5191 | 1.83 | 3378 | 98 100 | 3.44 |
| 2010–2022 | 1376 | 90 433 | 1.52 | 37 490 | 1 323 391 | 2.83 |
TABLE 3.
Participant background.
| Fukushima (n = 1247) | Other areas (n = 36 365) | |
|---|---|---|
| Median maternal age—year (range) | 31 (15–49) | 33 (14–53) |
| Primipara—number (%) | 607 (48.7) | 18 563 (51.0) |
| History of miscarriage—number (%) | 228 (18.3) | 7737 (21.2) |
| History of stillbirth—number (%) | 13 (1.0) | 372 (1.0) |
| Median birth weight—gram (range) | 2926 (266–4330) | 2763 (74–5408) |
| Male—number (%) | 662 (53.1) | 19 792 (54.4) |
| Female—number (%) | 584 (46.8) | 16 454 (45.2) |
| Gender unknown—number (%) | 1 (0.1) | 119 (0.3) |
| Single birth—number (%) | 1211 (97.6) | 34 531 (95.0) |
| Multiple births—number (%) | 36 (2.9) | 1846 (5.1) |
| Smoking less than 16 weeks' gestation—number (%) | 124 (9.9) | 1982 (5.4) |
| Alcohol consumption less than 16 weeks' gestation—number (%) | 95 (7.6) | 2051 (5.6) |
| Oral medication less than 16 weeks' gestation—number (%) | 258 (20.7) | 4387 (12.1) |
| Radiation exposure less than 16 weeks' gestation—number (%) | 10 (0.8) | 160 (0.4) |
| Oral folic acid—number (%) | 391 (31.4) | 8826 (24.2) |
We assessed the incidence of radiation‐induced malformations in Fukushima and other areas in Japan by calculating the incidence of microcephaly, microphthalmia, and neural tube defects. After FDND, the incidence of radiation‐induced malformations in Fukushima never surpassed that in Japan, with statistical significance (Figure 1A and Table S1). In Fukushima, the incidence of radiation‐induced malformations never surpassed 0.07% since 2011, whereas in other areas in Japan, the incidence was between 0.048 and 0.079. Since sampling bias was suspected, we adjusted the incidence of radiation‐induced malformations in Fukushima using the incidence of VSDs in Fukushima and other areas in Japan (Figure 1B and Table S2). After the adjustment, the incidences in Fukushima were between 0.057% and 0.151%, which were not higher than those in the other areas with statistical significance, except in 2017 (Figure 1B). In 2017, six patients with radiation‐induced malformations in Fukushima were observed. One patient and five patients were diagnosed with microphthalmia and spina bifida, respectively.
FIGURE 1.
Incidence of radiation‐induced congenital birth defects in Fukushima and other areas in Japan. (A) Raw data. (B) Adjusted incidences in Fukushima were calculated using the numbers of VSDs in both areas. CI, confidence interval.
4. DISCUSSION
This study showed no increase in radiation‐induced malformations such as neural tube closure defects, microcephaly, or microphthalmia in Fukushima after FDND. This study has two strengths. First, using data from the ICBDSR, the only Japanese survey of congenital birth defects, we were able to evaluate the annual trends in congenital birth defects on a national scale. Second, the Fukushima Prefecture participant population in this study represents the general population of pregnant Japanese women, including both low‐ and high‐risk pregnant women.
In our analysis, the incidence of radiation‐induced malformations has never surpassed 0.07% in Fukushima since 2011. They are not higher than those in other areas in Japan. Among the phenotypes we used for radiation‐induced malformations, neural tube defects occur most frequently, of which an estimated average global prevalence is 0.2%. 21 Microcephaly and microphthalmia are rarer phenotypes. Their prevalences vary across studies but are generally reported to be less than 0.1%. 22 , 23 Taken together, the incidences of these phenotypes in Fukushima were not higher than national and worldwide baseline prevalences.
Several reports have mentioned the relationship between FDND and health issues in Fukushima, including congenital birth defects, some of which are inconsistent. The UNSCEAR 2023 report states that there is no reliable evidence of birth defects, stillbirths, premature births, or low birth weight related to radiation exposure from FDND. 15 Additionally, several reports have mentioned that perinatal outcomes after FDND did not worsen. Yasuda et al. conducted a questionnaire survey of women who experienced FDND and compared perinatal outcomes based on estimated external radiation dose and reported no increase in congenital anomalies, low birth weight, or preterm delivery. 12 In a nationwide birth cohort study between 2011 and 2014, Kyozuka et al. reported that congenital birth defects were not higher in Fukushima Prefecture than those in other areas in Japan. 24 These studies differ from our study in that their endpoint was the number of all congenital birth defects, not only radiation‐induced malformations but also other diagnosable birth defects, in Fukushima Prefecture. Our study complements these previous reports in that we evaluated annual trends in radiation‐induced malformations, and the results suggest a low impact of radiation on pregnancies after FDND.
Our findings were consistent with those of previous reports; radiation exposure in Fukushima was lower than the threshold that causes radiation‐induced congenital malformations, which is estimated to be approximately 100–120 mGy. 25 , 26 For FDND, the estimated average effective dose of radiation for adult evacuees was <9 mSv. Another report states that in Fukushima Prefecture, the average external radiation dose during 4 months after the Great East Japan Earthquake was 0.7 mSv, and even in the highest area, the dose was estimated to be 4.0 mSv. 27 This lower radiation exposure might have benefited from the evacuation measures that took place soon after the Great East Japan Earthquake. 1 It was inferred that FDND did not cause radiation exposure sufficiently high to cause radiation‐induced malformations, and our results support this finding.
This study has several limitations. First, as mentioned in the Results section, sampling bias was suspected. In Japan, approximately half of the deliveries take place in primary care facilities, and the other half are handled in secondary or tertiary care centers, including centers for fetal diagnosis. 28 In general, low‐risk pregnancies are treated in primary care facilities, while high‐risk pregnancies, including maternal or fetal complications, are treated in secondary or tertiary centers. Therefore, we assume that the results from Fukushima reflect the general population, whereas those from other areas in Japan reflect a biased population of pregnancies with complications and fetal abnormalities. To address this, we adjusted the incidence of radiation‐induced malformations using the incidence of VSDs, which is the most common congenital birth defect and accounts for 1% of the general population. Nonetheless, this adjustment may be insufficient because the diagnostic rate of VSDs, especially small VSDs, varies among facilities, and the potential influence of radiation on VSD incidence has not been fully elucidated. Second, the patient backgrounds of the total population were not obtained; therefore, the patients were at a risk of observational bias. Third, the participants' radiation exposure was not quantified, and the place of residence of the participants in Fukushima was unavailable. Finally, the ICBDSR reports congenital birth defects identified in the first week after birth; therefore, it is impossible to assess diseases diagnosed later in that period, such as developmental issues and neoplasms. Due to these limitations, we were unable to conclude if a slight increase in Fukushima in 2017 was related to FDND or was coincidental.
In conclusion, we analyzed the ICBDSR data, which is the largest database of congenital malformations in Japan, to assess if radiation‐induced malformations in Fukushima have increased after FDND. Although the ICBDSR data does not include precise radiation exposure measurements and may be subject to sampling bias, our analysis found no evidence of an increase in radiation‐induced malformations in Fukushima.
FUNDING INFORMATION
This work was supported by the MHLW Health Research Program on Children, Youth, and Families (grant number: JPMH22HA2002).
CONFLICT OF INTEREST STATEMENT
Haruka Hamanoue is an Editorial Board member of Congenital Anomalies and a co‐author of this article. Others do not have conflict of interest.
ETHICS STATEMENT
This study was conducted according to the principles of the Declaration of Helsinki. This study was approved by the Institutional Review Board of Yokohama City University School of Medicine (A140925013).
Supporting information
Figure S1. Distributions of maternal ages and birth weights. (A) Fukushima. (B) The other areas of Japan.
Table S1. Incidence rate and 95% confidence interval of radiation‐related birth defects and VSDs (raw).
Table S2. Incidence rate and 95% confidence interval of radiation‐related birth defects in Fukushima (adjusted).
ACKNOWLEDGMENTS
We thank all participants, participating institutions, and medical staff who were involved in this precious data collection. During the submission of this paper, a co‐author, Fumiki Hirahara, passed away. Professor Emeritus Fumiki Hirahara has led the ICBDSR and made significant contributions to this paper. We would like to take this opportunity to express our deepest condolences and gratitude to him.
Kondo S, Itai T, Akamatsu C, et al. Radiation‐induced congenital malformations in Fukushima after the Fukushima Daiichi Nuclear Disaster. Congenit Anom. 2025;65(1):e70013. doi: 10.1111/cga.70013
DATA AVAILABILITY STATEMENT
The raw data for this study are available from the corresponding author upon reasonable request.
REFERENCES
- 1. Hasegawa A, Tanigawa K, Ohtsuru A, et al. Health effects of radiation and other health problems in the aftermath of nuclear accidents, with an emphasis on Fukushima. Lancet. 2015;386(9992):479‐488. doi: 10.1016/s0140-6736(15)61106-0 [DOI] [PubMed] [Google Scholar]
- 2. Streffer C, Shore R, Konermann G, et al. Biological effects after prenatal irradiation (embryo and fetus). A report of the international commission on radiological protection. Ann ICRP. 2003;33(1–2):5‐206. [PubMed] [Google Scholar]
- 3. De Santis M, Di Gianantonio E, Straface G, et al. Ionizing radiations in pregnancy and teratogenesis: a review of literature. Reprod Toxicol. 2005;20(3):323‐329. doi: 10.1016/j.reprotox.2005.04.004 [DOI] [PubMed] [Google Scholar]
- 4. Dekaban AS. Abnormalities in children exposed to x‐radiation during various stages of gestation: tentative timetable of radiation injury to the human fetus. J Nucl Med. 1968;9(9):471‐477. [PubMed] [Google Scholar]
- 5. Wertelecki W. Malformations in a chornobyl‐impacted region. Pediatrics. 2010;125(4):e836‐e843. doi: 10.1542/peds.2009-2219 [DOI] [PubMed] [Google Scholar]
- 6. Wertelecki W, Yevtushok L, Kuznietsov I, et al. Chornobyl, radiation, neural tube defects, and microcephaly. Eur J Med Genet. 2018;61(9):556‐563. doi: 10.1016/j.ejmg.2018.06.005 [DOI] [PubMed] [Google Scholar]
- 7. Kyozuka H, Murata T, Yasuda S, et al. The effects of the Great East Japan Earthquake on perinatal outcomes: results of the pregnancy and birth survey in the Fukushima health management survey. J Epidemiol. 2022;32(Suppl_XII):S57‐S63. doi: 10.2188/jea.JE20210444 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Leppold C, Nomura S, Sawano T, et al. Birth outcomes after the Fukushima Daiichi nuclear power plant disaster: a long‐term retrospective study. Int J Environ Res Public Health. 2017;14(5):542. doi: 10.3390/ijerph14050542 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Nishigori H, Fujimori K, Hosoya M, et al. Congenital anomalies in infants in Fukushima from 2011 to 2014: the Japan Environment and Children's Study. JMA J. 2023;6(1):36‐47. doi: 10.31662/jmaj.2022-0087 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10. United Nations . UNSCEAR 2020/2021 Report Volume I. Accessed Februar 10, 2025. https://www.unscear.org/unscear/en/publications/2020_2021_1.html
- 11. Yasuda S, Kyozuka H, Nomura Y, et al. Influence of the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Disaster on the birth weight of newborns in Fukushima prefecture: Fukushima Health Management Survey. J Matern Fetal Neonatal Med. 2017;30(24):2900‐2904. doi: 10.1080/14767058.2016.1245718 [DOI] [PubMed] [Google Scholar]
- 12. Yasuda S, Okazaki K, Nakano H, et al. Effects of external radiation exposure on perinatal outcomes in pregnant women after the Fukushima Daiichi nuclear power plant accident: the Fukushima Health Management Survey. J Epidemiol. 2022;32(Suppl_XII):S104‐S114. doi: 10.2188/jea.JE20210252 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13. Yasumura S, Ohira T, Ishikawa T, et al. Achievements and current status of the Fukushima Health Management Survey. J Epidemiol. 2022;32(Suppl_XII):S3‐S10. doi: 10.2188/jea.JE20210390 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14. Fujimori K, Kyozuka H, Yasuda S, et al. Pregnancy and birth survey after the Great East Japan Earthquake and Fukushima Daiichi nuclear power plant accident in Fukushima prefecture. Fukushima J Med Sci. 2014;60(1):75‐81. doi: 10.5387/fms.2014-9 [DOI] [PubMed] [Google Scholar]
- 15. United Nations . UNSCEAR 2020/2021 Report Volume II. Accessed February 10, 2025. https://www.unscear.org/unscear/publications/2020_2021_2.html
- 16. Craenen K, Verslegers M, Buset J, Baatout S, Moons L, Benotmane MA. A detailed characterization of congenital defects and mortality following moderate x‐ray doses during neurulation. Birth Defects Res. 2018;110(6):467‐482. doi: 10.1002/bdr2.1161 [DOI] [PubMed] [Google Scholar]
- 17. Leibovitz Z, Daniel‐Spiegel E, Malinger G, et al. Prediction of microcephaly at birth using three reference ranges for fetal head circumference: can we improve prenatal diagnosis? Ultrasound Obstet Gynecol. 2016;47(5):586‐592. doi: 10.1002/uog.15801 [DOI] [PubMed] [Google Scholar]
- 18. Shah SP, Taylor AE, Sowden JC, et al. Anophthalmos, microphthalmos, and typical coloboma in the United Kingdom: a prospective study of incidence and risk. Invest Ophthalmol Vis Sci. 2011;52(1):558‐564. doi: 10.1167/iovs.10-5263 [DOI] [PubMed] [Google Scholar]
- 19. statsmodels: Econometric and statistical modeling with python. 9th Python in Science Conference; 2010.
- 20. Virtanen P, Gommers R, Oliphant TE, et al. SciPy 1.0: fundamental algorithms for scientific computing in python. Nat Methods. 2020;17(3):261‐272. doi: 10.1038/s41592-019-0686-2 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21. Kancherla V. Neural tube defects: a review of global prevalence, causes, and primary prevention. Childs Nerv Syst. 2023;39(7):1703‐1710. doi: 10.1007/s00381-023-05910-7 [DOI] [PubMed] [Google Scholar]
- 22. Morris JK, Rankin J, Garne E, et al. Prevalence of microcephaly in Europe: population based study. BMJ. 2016;354:i4721. doi: 10.1136/bmj.i4721 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23. Chambers TM, Agopian AJ, Lewis RA, et al. Epidemiology of anophthalmia and microphthalmia: prevalence and patterns in Texas, 1999–2009. Am J Med Genet A. 2018;176(9):1810‐1818. doi: 10.1002/ajmg.a.40352 [DOI] [PubMed] [Google Scholar]
- 24. Kyozuka H, Fujimori K, Hosoya M, et al. The Japan Environment and Children's Study (JECS) in Fukushima prefecture: pregnancy outcome after the Great East Japan Earthquake. Tohoku J Exp Med. 2018;246(1):27‐33. doi: 10.1620/tjem.246.27 [DOI] [PubMed] [Google Scholar]
- 25. De Santis M, Cesari E, Nobili E, Straface G, Cavaliere AF, Caruso A. Radiation effects on development. Birth Defects Res C Embryo Today. 2007;81(3):177‐182. doi: 10.1002/bdrc.20099 [DOI] [PubMed] [Google Scholar]
- 26. Otake MSW, Yoshimaru H. A review of forty‐five years study of Hiroshima and Nagasaki atomic bomb survivors. Brain damage among the prenatally exposed. J Radiat Res. 1991;32:249‐264. [DOI] [PubMed] [Google Scholar]
- 27. Ishikawa T, Yasumura S, Akahane K, et al. External doses available for epidemiological studies related to the Fukushima health management survey: first 4‐month individual doses and municipality‐average doses for the first year. J Epidemiol. 2022;32(Suppl_XII):S11‐S22. doi: 10.2188/jea.JE20210166 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28. Japan Association of Obstetricians and Gynecologists . Survey of Obstetrics and Gynecology Facilities in Japan. Accessed February 10, 2025. https://www.jaog.or.jp/wp/wp-content/uploads/2023/02/48dc1841822ac2ca56d3d7ee4b107c28.pdf
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Figure S1. Distributions of maternal ages and birth weights. (A) Fukushima. (B) The other areas of Japan.
Table S1. Incidence rate and 95% confidence interval of radiation‐related birth defects and VSDs (raw).
Table S2. Incidence rate and 95% confidence interval of radiation‐related birth defects in Fukushima (adjusted).
Data Availability Statement
The raw data for this study are available from the corresponding author upon reasonable request.