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PloS One 2019Previous research indicated that birth order was associated with physical health outcomes in adulthood. However, evidence on its association with mental health was...
BACKGROUND
Previous research indicated that birth order was associated with physical health outcomes in adulthood. However, evidence on its association with mental health was lacking. The aim of this study was to investigate if birth order was associated with mental wellbeing and psychological distress at mid-life, stratified by gender, and taking into account confounding factors in childhood and adulthood.
METHOD
The sample consisted of 9,354 participants of the 1970 British Cohort Study (BCS70). The Warwick Edinburgh Mental Wellbeing Scale (WEMWBS), the Malaise Index and attending a doctor's consultation in the past year for a mental health issue at age forty-two were used to assess mental wellbeing and psychological distress in midlife. Birth order was ascertained via a parental questionnaire and referred to the numerical birth position of the participants. The associations between birth order, mental wellbeing and psychological distress were tested using linear and logistic regression adjusting for birth characteristics: smoking during pregnancy, maternal age, mother's marital status, father's employment, region of birth, parental years of education and parental social class, and factors at age 42: years of education, employment status and partnership status. Potential mediating variables including breastfeeding and birthweight at birth and parental separation and conduct disorder measured at age ten were also taken into account.
RESULTS
We find no evidence to support an association between birth order and midlife psychological distress or attending a doctor's consultation in both men and women. In unadjusted analysis, there was an association between birth order four and above and a reduced WEMWBS score of -0.79 (95% CI -1.57, -0.02) in men only. This association was attenuated after adjusting for birth characteristics and mediators at birth (0.86, 95% -1.78, 0.07) but was maintained once conduct disorder at age 10 was accounted for (-1.19, 95% CI -2.28, -0.09). However, this association was attenuated once again after adjusting for employment status, years in education and partnership status in adulthood (-1.04, 95% CI -2.11, 0.03).
CONCLUSIONS
In this study, birth order was not associated with psychological distress or having a mental health issue at midlife. Accounting for employment status, years of education and partnership status in adulthood attenuated the relationship between birth order and mental wellbeing.
Topics: Adult; Age Factors; Birth Order; Cohort Studies; Female; Humans; Longitudinal Studies; Male; Mental Health; Outcome Assessment, Health Care; Psychological Distress; Risk Factors; United Kingdom
PubMed: 31527876
DOI: 10.1371/journal.pone.0222184 -
Hormones and Behavior Mar 2020We review research supporting biological mechanisms in the development of sexual orientation. This research includes studies on neural correlates, prenatal hormones and... (Review)
Review
We review research supporting biological mechanisms in the development of sexual orientation. This research includes studies on neural correlates, prenatal hormones and related physical/behavioral correlates, genetics, and the fraternal birth order effect (FBOE). These studies, taken together, have provided substantial support for biological influences underlying the development of sexual orientation, but questions remain unanswered, including how biological mechanisms may differ in contributing to men's and women's sexual orientation development.
Topics: Adult; Biomedical Research; Birth Order; Female; Homosexuality, Male; Hormones; Humans; Male; Pregnancy; Prenatal Exposure Delayed Effects; Sex Determination Processes; Sexual Behavior
PubMed: 31911036
DOI: 10.1016/j.yhbeh.2019.104659 -
International Journal of Cancer Jun 2011The causes of childhood cancers are largely unknown. Birth order has been used as a proxy for prenatal and postnatal exposures, such as frequency of infections and in... (Comparative Study)
Comparative Study
The causes of childhood cancers are largely unknown. Birth order has been used as a proxy for prenatal and postnatal exposures, such as frequency of infections and in utero hormone exposures. We investigated the association between birth order and childhood cancers in a pooled case-control dataset. The subjects were drawn from population-based registries of cancers and births in California, Minnesota, New York, Texas and Washington. We included 17,672 cases <15 years of age who were diagnosed from 1980 to 2004 and 57,966 randomly selected controls born 1970-2004, excluding children with Down syndrome. We calculated odds ratios and 95% confidence intervals using logistic regression, adjusted for sex, birth year, maternal race, maternal age, multiple birth, gestational age and birth weight. Overall, we found an inverse relationship between childhood cancer risk and birth order. For children in the fourth or higher birth order category compared to first-born children, the adjusted OR was 0.87 (95% CI: 0.81, 0.93) for all cancers combined. When we examined risks by cancer type, a decreasing risk with increasing birth order was seen in the central nervous system tumors, neuroblastoma, bilateral retinoblastoma, Wilms tumor and rhabdomyosarcoma. We observed increased risks with increasing birth order for acute myeloid leukemia but a slight decrease in risk for acute lymphoid leukemia. These risk estimates were based on a very large sample size, which allowed us to examine rare cancer types with greater statistical power than in most previous studies, however the biologic mechanisms remain to be elucidated.
Topics: Adolescent; Adult; Birth Order; Case-Control Studies; Child; Child, Preschool; Female; Humans; Incidence; Infant; Infant, Newborn; Leukemia, Myeloid, Acute; Male; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Prognosis; Survival Rate; United States; Young Adult
PubMed: 20715170
DOI: 10.1002/ijc.25593 -
Pediatric Obesity Feb 2016This study aimed to examine the association of birth order and number and sex of siblings with overweight or obesity among 4- to 8-year-olds.
OBJECTIVE
This study aimed to examine the association of birth order and number and sex of siblings with overweight or obesity among 4- to 8-year-olds.
METHODS
This is a cross-sectional study involving 273 low-income mother-child dyads. Questionnaires and anthropometry were completed. Multiple logistic regression was used to examine the association of birth order, having younger siblings, having older siblings, having at least one brother and having at least one sister with odds of overweight or obesity. Analyses were repeated to additionally include non-biological siblings. Models were adjusted for potential confounders and intermediate variables.
RESULTS
Prevalence of child overweight or obesity was 42.5%. Adjusting for covariates, only children and youngest siblings had higher odds of overweight or obesity compared with oldest siblings (odds ratio [OR]: 4.18, 95% confidence interval [CI]: 1.67, 10.46 and OR: 3.21, 95% CI: 1.41, 7.33, respectively). Having one or more younger siblings and having at least one brother were associated with lower odds (OR: 0.38, 95% CI: 0.21, 0.69 and OR: 0.47, 95% CI: 0.28, 0.81, respectively). Including non-biological siblings did not meaningfully change the associations.
CONCLUSION
Birth order and sibship composition are associated with overweight or obesity among 4- to 8-year-olds. Future studies identifying the underlying behavioural mechanism can help inform family-based intervention programmes.
Topics: Birth Order; Body Composition; Child; Cross-Sectional Studies; Female; Humans; Logistic Models; Male; Odds Ratio; Overweight; Poverty; Predictive Value of Tests; Prevalence; Risk Factors; Siblings; Surveys and Questionnaires
PubMed: 25735955
DOI: 10.1111/ijpo.12018 -
Cortex; a Journal Devoted To the Study... Dec 1983The handedness of 1,186 children about to enter kindergarten was tested. The sample represented approximately 98 percent of all children of this age in a school system...
The handedness of 1,186 children about to enter kindergarten was tested. The sample represented approximately 98 percent of all children of this age in a school system during 8 years. Handedness was examined in relation to birth order, maternal age at birth, and sex, for 1,097 subjects (92.5%), and in relation to season of birth for the total sample. The finding that there were significantly more nonright-handed boys for birth orders one and four-or-later, than for two and three, provides support for Bakan (1971). There was a nonsignificant increase in nonright-handedness for boys born to the youngest (less than 20) and oldest (less than 30) mothers. A significant seasonal effect for the birth of nonright-handed boys was observed. For each of the fall and winter months (September - February) the proportion of nonright-handed male births was higher than that for any of the spring and summer months. For girls, no significant effects on handedness were observed, for birth order, maternal age, or season of birth.
Topics: Birth Order; Child, Preschool; Female; Functional Laterality; Humans; Male; Maternal Age; Seasons; Sex Factors
PubMed: 6671390
DOI: 10.1016/s0010-9452(83)80027-6 -
American Journal of Epidemiology Sep 2010There is inconsistent evidence that increasing birth order may be associated with risk of non-Hodgkin lymphoma (NHL). The authors examined the association between birth... (Meta-Analysis)
Meta-Analysis
There is inconsistent evidence that increasing birth order may be associated with risk of non-Hodgkin lymphoma (NHL). The authors examined the association between birth order and related variables and NHL risk in a pooled analysis (1983-2005) of 13,535 cases and 16,427 controls from 18 case-control studies within the International Lymphoma Epidemiology Consortium (InterLymph). Overall, the authors found no significant association between increasing birth order and risk of NHL (P-trend = 0.082) and significant heterogeneity. However, a significant association was present for a number of B- and T-cell NHL subtypes. There was considerable variation in the study-specific risks which was partly explained by study design and participant characteristics. In particular, a significant positive association was present in population-based studies, which had lower response rates in cases and controls, but not in hospital-based studies. A significant positive association was present in higher-socioeconomic-status (SES) participants only. Results were very similar for the related variable of sibship size. The known correlation of high birth order with low SES suggests that selection bias related to SES may be responsible for the association between birth order and NHL.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Birth Order; Case-Control Studies; Female; Humans; Lymphoma, Non-Hodgkin; Male; Middle Aged; Siblings; Socioeconomic Factors; Young Adult
PubMed: 20720098
DOI: 10.1093/aje/kwq167 -
Archives of Sexual Behavior Feb 2020The fraternal birth order (FBO) effect related to men's sexual orientation refers to the finding that the number of older brothers that a man has increases his chance of...
The fraternal birth order (FBO) effect related to men's sexual orientation refers to the finding that the number of older brothers that a man has increases his chance of being androphilic. The FBO effect has generally been well replicated in diverse samples; one instance of non-replication was by Francis (2008) using Waves I and III of the Add Health data. We attempted to replicate the FBO effect in the Add Health data taking into account family size and other limitations of Francis' (2008) analyses. Also, we examined other sibling characteristics related to the FBO effect: sibling sex ratio and only-child status. We used two subsamples from Waves I (n = 20,745) and IV (n = 15,701) of the Add Health data, consisting of adolescents who were followed longitudinally from 1994 to 1995 until 2008. Wave I data were used to compute numbers of younger and older brothers and sisters from household roster information. Wave IV information about sexual orientation identity was used. Analyses were conducted within men and within women. We found modest support for the FBO effect in men, but not in women, using the older brother odds ratio, logistic regression analyses, and sibling sex ratio, which provided the strongest support for FBO. We found that gynephilic/biphilic women, but not androphilic/biphilic men, were more likely to be only-children compared to androphilic women and gynephilic men, respectively. We discuss limitations of the Add Health data and purported mechanisms for the FBO effect in men and the only-child effect in women.
Topics: Adult; Birth Order; Female; Humans; Longitudinal Studies; Male; Only Child; Sex Ratio; Sexual Behavior; Siblings
PubMed: 31802291
DOI: 10.1007/s10508-019-01496-x -
British Journal of Cancer Oct 2011Carcinomas in children are rare and have not been well studied.
BACKGROUND
Carcinomas in children are rare and have not been well studied.
METHODS
We conducted a population-based case-control study and examined associations between birth characteristics and childhood carcinomas diagnosed from 28 days to 14 years during 1980-2004 using pooled data from five states (NY, WA, MN, TX, and CA) that linked their birth and cancer registries. The pooled data set contained 57,966 controls and 475 carcinoma cases, including 159 thyroid and 126 malignant melanoma cases. We used unconditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs).
RESULTS
White compared with 'other' race was positively associated with melanoma (OR=3.22, 95% CI 1.33-8.33). Older maternal age increased the risk for melanoma (OR(per 5-year age increase)=1.20, 95% CI 1.00-1.44), whereas paternal age increased the risk for any carcinoma (OR=1.10(per 5-year age increase), 95% CI 1.01-1.20) and thyroid carcinoma (OR(per 5-year age increase)=1.16, 95% CI 1.01-1.33). Gestational age < 37 vs 37-42 weeks increased the risk for thyroid carcinoma (OR=1.87, 95% CI 1.07-3.27). Plurality, birth weight, and birth order were not significantly associated with childhood carcinomas.
CONCLUSION
This exploratory study indicates that some birth characteristics including older parental age and low gestational age may be related to childhood carcinoma aetiology.
Topics: Adolescent; Birth Order; Birth Weight; Case-Control Studies; Child; Child, Preschool; Female; Gestational Age; Humans; Infant; Infant, Newborn; Male; Maternal Age; Melanoma; Neoplasms; Paternal Age; Risk; Thyroid Neoplasms
PubMed: 21915125
DOI: 10.1038/bjc.2011.359 -
Journal of Preventive Medicine and... Dec 2020This study was conducted to examine the association between birth patterns (defined in terms of birth order and interval) with delayed breastfeeding initiation in...
OBJECTIVES
This study was conducted to examine the association between birth patterns (defined in terms of birth order and interval) with delayed breastfeeding initiation in Indonesia.
METHODS
A cross-sectional study was carried out using data from the Indonesian Demographic and Health Survey 2017. The weighted number of respondents was 5693 women aged 15-49 years whose youngest living child was less than 2 years old. Multivariable logistic regression was conducted to evaluate associations between birth patterns and delayed breastfeeding initiation after adjusting for other covariates.
RESULTS
This study found that 40.2% of newborns in Indonesia did not receive timely breastfeeding initiation. Birth patterns were significantly associated with delayed breastfeeding initiation. Firstborn children had 77% higher odds of experiencing delayed breastfeeding initiation (adjusted odds ratio, 1.77; 95% confidence interval, 1.02 to 3.04; p<0.05) than children with a birth order of 4 or higher and a birth interval ≤ 2 years after adjusting for other variables.
CONCLUSIONS
Firstborn children had higher odds of experiencing delayed breastfeeding initiation. Steps to provide a robust support system for mothers, especially first-time mothers, such as sufficient access to breastfeeding information, support from family and healthcare providers, and national policy enforcement, will be effective strategies to ensure better practices regarding breastfeeding initiation.
Topics: Adolescent; Adult; Birth Intervals; Birth Order; Breast Feeding; Cross-Sectional Studies; Female; Humans; Indonesia; Logistic Models; Middle Aged; Odds Ratio; Pregnancy; Socioeconomic Factors
PubMed: 33296587
DOI: 10.3961/jpmph.20.212 -
JAMA Ophthalmology Dec 2015Visual impairment due to myopia is an important public health issue. A prior analysis of population-based cohorts aged 15 to 22 years recruited from the United Kingdom...
IMPORTANCE
Visual impairment due to myopia is an important public health issue. A prior analysis of population-based cohorts aged 15 to 22 years recruited from the United Kingdom and Israel suggested myopia and high myopia were approximately 10% more common in first-born compared with later-born children.
OBJECTIVE
To examine whether myopia was associated with birth order in an earlier generation than studied previously and, if so, whether the association was attenuated after adjusting for education exposure, as predicted by the hypothesis that the education of children with later birth orders is less intense.
DESIGN, SETTING, AND PARTICIPANTS
Cross-sectional study of UK Biobank participants recruited from 2006 to 2010. Analysis was restricted to participants aged 40 to 69 years who had a vision assessment, self-reported white ethnicity, and no history of eye disorders (N = 89,120). Myopia and high myopia were defined as autorefraction of -0.75 diopters (D) or less and -6.00 D or less, respectively.
EXPOSURES
Birth order and information on potential confounders including highest educational qualification ascertained using a structured questionnaire.
MAIN OUTCOMES AND MEASURES
Odds ratios (ORs) for myopia and high myopia by birth order, using logistic regression and adjusting for age and sex (model 1) or age, sex, and highest educational qualification (model 2).
RESULTS
In model 1 (no adjustment for education), birth order was associated with both myopia and high myopia (eg, comparing first- vs second-born individuals; OR, 1.12; 95% CI, 1.08-1.16; P = 1.40E-11 and OR, 1.21; 95% CI, 1.11-1.30; P = 3.60E-06 for myopia and high myopia, respectively). The risk for myopia became progressively lower for later birth orders, suggesting a dose response. In model 2 (after adjusting for education), the effect sizes were attenuated by approximately 25% (OR, 1.09; 95% CI, 1.05-1.12; P = 1.30E-06 and OR, 1.15; 95% CI, 1.06-1.25; P = 4.60E-04 for myopia and high myopia, respectively) and the apparent dose response was abolished.
CONCLUSIONS AND RELEVANCE
These data suggest that the association between birth order and myopia is not due to a new environmental pressure in the last 30 to 40 years. The attenuated effect size after adjusting for educational exposure supports a role for reduced parental investment in education of children with later birth orders in their relative protection from myopia.
Topics: Adult; Aged; Birth Order; Cross-Sectional Studies; Educational Status; Female; Humans; Male; Middle Aged; Myopia; Odds Ratio; Prevalence; Risk Factors; Surveys and Questionnaires; United Kingdom
PubMed: 26448589
DOI: 10.1001/jamaophthalmol.2015.3556