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Bruckner TA, Chakrabarti S, Bustos B, Catalano R, Gemmill A, Casey JA, Lee H. Missing Black males among preterm births in the US, 1995 to 2019. PLoS One 2024; 19:e0295557. [PMID: 38498466 PMCID: PMC10947666 DOI: 10.1371/journal.pone.0295557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 11/24/2023] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND In the US, non-Hispanic (NH) Black birthing persons show a two-fold greater risk of fetal death relative to NH white birthing persons. Since males more than females show a greater risk of fetal death, such loss in utero may affect the sex composition of live births born preterm (PTB; <37 weeks gestational age). We examine US birth data from 1995 to 2019 to determine whether the ratio of male to female preterm (i.e., PTB sex ratios) among NH Black births falls below that of NH whites and Hispanics. METHODS We acquired data on all live births in the US from January 1995 to December 2019. We arrayed 63 million live births into 293 "conception cohort" months of which 2,475,928 NH Black, 5,746,953 NH white, and 2,511,450 Hispanic infants were PTB. We used linear regression methods to identify trend and seasonal patterns in PTB sex ratios. We also examined subgroup differences in PTB sex ratios (e.g., advanced maternal ages, twin gestations, and narrower gestational age ranges). RESULTS The mean PTB sex ratio for NH Black births over the entire test period (1.06, 95% Confidence Interval [CI]: 1.05, 1.07) is much lower than that for NH white births (1.18, 95% CI: 1.17, 1.19). NH Black PTB sex ratios are especially low for twins and for births to mothers 35 years or older. Only NH white PTB sex ratios show a trend over the test period. CONCLUSIONS Analysis of over 10 million PTBs reveals a persistently low male PTB frequency among NH Black conception cohorts relative to NH white cohorts. Low PTB sex ratios among NH Black births concentrate among subgroups that show an elevated risk of fetal death. PTB sex ratios may serve as an indicator of racial/ethnic and subgroup differences in fetal death, especially among male gestations.
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Affiliation(s)
- Tim A. Bruckner
- Department of Health, Society, and Behavior, and the Center for Population, Inequality, and Policy, University of California, Irvine, Irvine, California, United States of America
| | | | - Brenda Bustos
- Program in Public Health, University of California, Irvine, Irvine, California, United States of America
| | - Ralph Catalano
- School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Alison Gemmill
- Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Joan A. Casey
- Department of Environmental and Occupational Health Sciences, University of Washington School of Public Health, Seattle, Washington, United States of America
| | - Hedwig Lee
- Department of Sociology, Duke University, Durham, North Carolina, United States of America
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Margerison CE, Bruckner TA, MacCallum-Bridges C, Catalano R, Casey JA, Gemmill A. Exposure to the early COVID-19 pandemic and early, moderate and overall preterm births in the United States: A conception cohort approach. Paediatr Perinat Epidemiol 2023; 37:104-112. [PMID: 35830303 PMCID: PMC9350314 DOI: 10.1111/ppe.12894] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/27/2022] [Accepted: 05/01/2022] [Indexed: 01/17/2023]
Abstract
BACKGROUND The United States (US) data suggest fewer-than-expected preterm births in 2020, but no study has examined the impact of exposure to the early COVID-19 pandemic at different points in gestation on preterm birth. OBJECTIVE Our objective was to determine-among cohorts exposed to the early COVID-19 pandemic-whether observed counts of overall, early and moderately preterm birth fell outside the expected range. METHODS We used de-identified, cross-sectional, national birth certificate data from 2014 to 2020. We used month and year of birth and gestational age to estimate month of conception for birth. We calculated the count of overall (<37 weeks gestation), early (<33 weeks gestation) and moderately (33 to <37 weeks gestation) preterm birth by month of conception. We employed time series methods to estimate expected counts of preterm birth for exposed conception cohorts and identified cohorts for whom the observed counts of preterm birth fell outside the 95% detection interval of the expected value. RESULTS Among the 23,731,146 births in our study, the mean prevalence of preterm birth among monthly conception cohorts was 9.7 per 100 live births. Gestations conceived in July, August or December of 2019-that is exposed to the early COVID-19 pandemic in the first or third trimester-yielded approximately 3245 fewer moderately preterm and 3627 fewer overall preterm births than the expected values for moderate and overall preterm. Gestations conceived in August and October of 2019-that is exposed to the early COVID-19 pandemic in the late second to third trimester-produced approximately 498 fewer early preterm births than the expected count for early preterm. CONCLUSIONS Exposure to the early COVID-19 pandemic may have promoted longer gestation among close-to-term pregnancies, reduced risk of later preterm delivery among gestations exposed in the first trimester or induced selective loss of gestations.
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Affiliation(s)
| | - Tim A. Bruckner
- Department of Health, Society, and Behavior, and the Center for Population, Inequality, and Policy, University of California, Irvine
| | | | - Ralph Catalano
- School of Public Health, University of California, Berkeley
| | - Joan A. Casey
- Department of Environmental Health Sciences, Columbia Mailman School of Public Health
| | - Alison Gemmill
- Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health
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African American Unemployment and the Disparity in Periviable Births. J Racial Ethn Health Disparities 2021; 9:840-848. [PMID: 33783756 PMCID: PMC9061667 DOI: 10.1007/s40615-021-01022-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/11/2021] [Accepted: 03/14/2021] [Indexed: 11/16/2022]
Abstract
Periviable infants (i.e., born before 26 complete weeks of gestation) represent fewer than .5% of births in the US but account for 40% of infant mortality and 20% of billed hospital obstetric costs. African American women contribute about 14% of live births in the US, but these include nearly a third of the country’s periviable births. Consistent with theory and with periviable births among other race/ethnicity groups, males predominate among African American periviable births in stressed populations. We test the hypothesis that the disparity in periviable male births among African American and non-Hispanic white populations responds to the African American unemployment rate because that indicator not only traces, but also contributes to, the prevalence of stress in the population. We use time-series methods that control for autocorrelation including secular trends, seasonality, and the tendency to remain elevated or depressed after high or low values. The racial disparity in male periviable birth increases by 4.45% for each percentage point increase in the unemployment rate of African Americans above its expected value. We infer that unemployment—a population stressor over which our institutions exercise considerable control—affects the disparity between African American and non-Hispanic white periviable births in the US.
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Catalano R, Bruckner TA, Karasek D, Yang W, Shaw GM. Reproductive suppression, birth defects, and periviable birth. Evol Appl 2018; 11:762-767. [PMID: 29875817 PMCID: PMC5979761 DOI: 10.1111/eva.12585] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/13/2017] [Indexed: 12/15/2022] Open
Abstract
We argue that reproductive suppression has clinical implications beyond its contribution to the burden of spontaneous abortion. We theorize that the incidence of births before the 28th week of gestation, which contribute disproportionately to infant morbidity and mortality, varies over time in part due to reproductive suppression in the form of selection in utero. We further theorize that the prevalence of structural birth defects among survivors to birth from conception cohorts gauges selection in utero. We based these theories on literature positing that natural selection conserved mechanisms that spontaneously abort "risky" pregnancies including those otherwise likely to yield infants with structural birth defects or small-for-gestational age males. We test our theory using high-quality birth defect surveillance data. We identify 479,885 male infants exposed to strong selection defined as membership in conception cohorts ranked in the lowest quartile of odds of a birth defect among live-born females. We estimate the risk of periviable birth among these infants as a function of selective pressure as well as of mother's race/ethnicity and age. We find that male infants from exposed conception cohorts exhibited 10% lower odds of periviable birth than males from other conception cohorts. Our findings support the argument that selection in utero has implications beyond its contribution to the burden of spontaneous abortion.
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Affiliation(s)
- Ralph Catalano
- School of Public HealthUniversity of CaliforniaBerkeleyCAUSA
| | | | - Deborah Karasek
- School of Public HealthUniversity of CaliforniaBerkeleyCAUSA
| | - Wei Yang
- Department of PediatricsDivision of NeonatologyStanford University School of MedicineStanfordCAUSA
| | - Gary M. Shaw
- Department of PediatricsDivision of NeonatologyStanford University School of MedicineStanfordCAUSA
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Bruckner TA, Karasek D, Yang W, Shaw GM, Catalano RA. Cohort Variation in Selection During Pregnancy and Risk of Selected Birth Defects Among Males. Epidemiology 2018; 28:580-586. [PMID: 28346269 DOI: 10.1097/ede.0000000000000661] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The literature theorizes, but does not test, that variation over time in selective loss in utero affects the observed count of live-born birth defects cases. We test the hypothesis that the risk of birth defects among live-born males varies inversely with the strength of selection against males in utero. METHODS We identified a subset of six birth defect phenotypes among males from the California Birth Defects Monitoring Program, an active surveillance system for over 490,000 male singletons born in eight California counties from 1986 to 2004. We assigned each birth defect case infant to a monthly conception cohort at risk of selection in utero. We used the monthly sex ratio at birth (M:F), derived from each conception cohort, as the indicator of selection against males. We analyzed the odds ratio of birth defects with both individual-level logistic regression and aggregate time-series methods. RESULTS Consistent with selection in utero, male infants from conception cohorts with low outlying sex ratios (i.e., stronger selectivity) exhibit fewer than expected birth defects (adjusted odds ratio [OR] = 0.86; 95% confidence interval [CI] = 0.76, 0.98). Aggregate time-series tests also yield similar findings (OR = 0.81; 95% CI = 0.71, 0.90). CONCLUSIONS Our findings among males indicate that variation in the strength of selectivity in utero accounts for a portion of observed cohort differences in morbidity due to birth defects. These findings suggest that "revealed prevalence" of morbidity across birth cohorts varies, at least in part, from selective loss in utero. See video abstract at, http://links.lww.com/EDE/B209.
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Affiliation(s)
- Tim A Bruckner
- From the aProgram in Public Health, University of California, Irvine, Irvine, CA; bSchool of Public Health, University of California, Berkeley, Berkeley, CA; and cDivision of Neonatology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA
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James WH, Grech V. Can sex ratios at birth be used in the assessment of public health, and in the identification of causes of selected pathologies? Early Hum Dev 2018; 118:15-21. [PMID: 29428574 DOI: 10.1016/j.earlhumdev.2018.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 12/31/2017] [Accepted: 02/06/2018] [Indexed: 02/09/2023]
Abstract
This paper will consist of two parts. In the first, further support is given to the proposal that offspring sex ratios (proportions male) may usefully be regarded as indicators of public health. In the second, it is shown that sex ratios may help in the identification of the causes and effects of several pathologies that seriously impinge on public health viz. autism, testicular cancer, hepatitis B and toxoplasmosis.
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Affiliation(s)
- William H James
- Galton Laboratory, Department of Genetics, Evolution and Environment, University College London, London WC1E 6HH, UK
| | - Victor Grech
- Victor Grech, Academic Department of Paediatrics, University of Malta Medical School, Msida, Malta.
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Catalano R, Gemmill A, Casey J, Karasek D, Stewart H, Saxton K. Separating the Bruce and Trivers-Willard effects in theory and in human data. Am J Hum Biol 2017; 30. [PMID: 29083077 DOI: 10.1002/ajhb.23074] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 08/21/2017] [Accepted: 10/12/2017] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVES Theories of reproductive suppression predict that natural selection would conserve mechanisms that abort the gestation of offspring otherwise unlikely to thrive in prevailing environments. Research reports evidence among humans of at least two such mechanisms-the Trivers-Willard and Bruce Effects. No literature, however, compares the mechanisms nor estimates their relative contribution to observed characteristics of human birth cohorts. We describe similarities and differences between the Trivers-Willard and Bruce Effects and explore high quality historical data from Sweden to determine which mechanism better describes temporal variation in the ratio of males to females in birth cohorts. METHODS We measure Trivers-Willard exposures with the death rate among women of reproductive age. We measure Bruce exposures with the death rate among children. We use time-series regression methods to estimate the relative contribution of the Trivers-Willard and Bruce Effects to temporal variation in historical Swedish secondary sex ratio data. RESULTS We find that the Bruce Effect appears to be a better predictor of the secondary sex ratio than does the Trivers-Willard Effect. CONCLUSIONS Attempts to identify mechanisms by which reproductive suppression affects fetal loss and characteristics of human birth cohorts should consider the Bruce Effect as an alternative to the Trivers-Willard Effect.
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Affiliation(s)
- Ralph Catalano
- School of Public Health, University of California, Berkeley, Berkeley, California 94704
| | - Alison Gemmill
- Department of Demography, University of California, Berkeley, Berkeley, California 94720
| | - Joan Casey
- School of Public Health, University of California, Berkeley, Berkeley, California 94704
| | - Deborah Karasek
- School of Public Health, University of California, Berkeley, Berkeley, California 94704
| | - Holly Stewart
- School of Public Health, University of California, Berkeley, Berkeley, California 94704
| | - Katherine Saxton
- Department of Biology, Santa Clara University, Santa Clara, California 95053
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Abstract
The human sex ratio (proportion male) at birth (SRB) varies with many variables. Some of this variation has an established proximate cause. For instance, low SRB (more females) at birth are associated with various forms of stressful events or circumstances during or prior to pregnancy. These low SRB are almost certainly mainly caused by maternal-stress-induced male foetal loss. Other types of SRB variation are thought to be caused by hormonal variation in either or both parents around the time of conception. One or other of these two types of proximate cause seems to be responsible for most of the established variation of SRB. This will be illustrated here in respect of some selected forms of SRB variation. It seems likely that a clarification of the hormonal causes of SRB variation will also help explain the striking (apparent) inconsistencies in the results of reported tests of the influential Trivers-Willard hypothesis. It is further proposed that an appreciation of the evidence that parental hormones influence SRB may enhance understanding of several important pathologies (hepatitis B, toxoplasmosis, testicular cancer, prostate cancer and autism).
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Affiliation(s)
- William H James
- The Galton Laboratory, Department of Genetics, Evolution and Environment, University College London, United Kingdom.
| | - Victor Grech
- Department of Paediatrics, Mater Dei Hospital Medical School, Malta.
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