TY - JOUR
T1 - Effects of maternal exposure to lead on secondary sex ratio in Japan
T2 - The Japan Environment and Children's Study
AU - The Japan Environment and Children's Study Group
AU - Tatsuta, Nozomi
AU - Nakai, Kunihiko
AU - Nakayama, Shoji F.
AU - Takeuchi, Ayano
AU - Arima, Takahiro
AU - Yaegashi, Nobuo
AU - Kamijima, Michihiro
AU - Yamazaki, Shin
AU - Ohya, Yukihiro
AU - Kishi, Reiko
AU - Hashimoto, Koichi
AU - Mori, Chisato
AU - Ito, Shuichi
AU - Yamagata, Zentaro
AU - Inadera, Hidekuni
AU - Nakayama, Takeo
AU - Iso, Hiroyasu
AU - Shima, Masayuki
AU - Kurozawa, Youichi
AU - Suganuma, Narufumi
AU - Kusuhara, Koichi
AU - Katoh, Takahiko
N1 - Funding Information:
This study was funded by the Ministry of the Environment, Japan . The funding sources had no role in the study protocol, in the collection, analysis, and interpretation of data, the writing of the report, or in the decision to submit the paper for publication. For this reason, the findings and conclusions of this article are solely the responsibility of the authors and do not represent the official views of the above government agencies.
Publisher Copyright:
© 2021
PY - 2022/4/15
Y1 - 2022/4/15
N2 - A decline in the proportion of male births (secondary sex ratio, SSR) has been seen in several countries including Japan in recent years. Although previous studies have reported that the SSR is affected by exposure to chemical substances such as dioxins and polychlorinated biphenyls, as well as heavy metals such as methylmercury, the effects of lead exposure on the SSR have been little studied. The aim of this study was to determine the association between maternal lead exposure and SSR. In a large-scale nationwide birth cohort study, maternal blood lead level (BLL) was determined using whole blood from the second or third trimester of pregnancy. The association between SSR and maternal BLL was estimated using multivariable logistic models. Binomial distribution was applied to examine the differences in SSR by dividing the participants into five groups based on BLL. The primary outcome was SSR, and the child sex was obtained from the medical record transcripts. Of 104,062 fetal records, 85,171 were examined for analysis. The median maternal BLL was 5.85 ng/g (5th–95th percentile 3.45–10.6 ng/g). The overall proportion of males among participating infants was 0.512. In logistic regression models adjusted for covariates, the analysis revealed an increased odds ratio for SSR with higher blood lead concentrations [Group 2: adjusted OR 1.082, 95% confidence interval 1.037 to 1.129, Group 3: 1.122, 1.074 to 1.171, Group 4: 1.214, 1.163 to 1.268, Group 5: 1.279, 1.224 to 1.336]. Compared to the general birth probability in Japan, the group with low BLL had a lower SSR and the group with high BLL had a higher SSR. Higher maternal lead exposures during pregnancy were associated with increased SSR. Further investigations including assessment of paternal lead exposure are necessary to understand the association between lead exposure and SSR.
AB - A decline in the proportion of male births (secondary sex ratio, SSR) has been seen in several countries including Japan in recent years. Although previous studies have reported that the SSR is affected by exposure to chemical substances such as dioxins and polychlorinated biphenyls, as well as heavy metals such as methylmercury, the effects of lead exposure on the SSR have been little studied. The aim of this study was to determine the association between maternal lead exposure and SSR. In a large-scale nationwide birth cohort study, maternal blood lead level (BLL) was determined using whole blood from the second or third trimester of pregnancy. The association between SSR and maternal BLL was estimated using multivariable logistic models. Binomial distribution was applied to examine the differences in SSR by dividing the participants into five groups based on BLL. The primary outcome was SSR, and the child sex was obtained from the medical record transcripts. Of 104,062 fetal records, 85,171 were examined for analysis. The median maternal BLL was 5.85 ng/g (5th–95th percentile 3.45–10.6 ng/g). The overall proportion of males among participating infants was 0.512. In logistic regression models adjusted for covariates, the analysis revealed an increased odds ratio for SSR with higher blood lead concentrations [Group 2: adjusted OR 1.082, 95% confidence interval 1.037 to 1.129, Group 3: 1.122, 1.074 to 1.171, Group 4: 1.214, 1.163 to 1.268, Group 5: 1.279, 1.224 to 1.336]. Compared to the general birth probability in Japan, the group with low BLL had a lower SSR and the group with high BLL had a higher SSR. Higher maternal lead exposures during pregnancy were associated with increased SSR. Further investigations including assessment of paternal lead exposure are necessary to understand the association between lead exposure and SSR.
KW - Air lead level
KW - Blood lead level
KW - Lead
KW - Prenatal exposure
KW - Secondary sex ratio
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UR - http://www.scopus.com/inward/citedby.url?scp=85122970633&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2021.152726
DO - 10.1016/j.scitotenv.2021.152726
M3 - Article
C2 - 34995582
AN - SCOPUS:85122970633
SN - 0048-9697
VL - 817
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 152726
ER -