Disease relevance of Birth Order

• Comparing class III homozygotes with other genotypes using multivariate linear regression analysis, we found no significant associations with any early growth measure (birth weight, birth length, ponderal index, and head circumference at 1 year), even after stratifying subjects by growth trajectory during infancy and/or birth order [1].
• We observed no association between any other reproductive factors examined (age at first birth, menarche, or menopause; type of menopause; diethylstilbestrol (DES) use; or duration of oral contraceptive or estrogen replacement therapy use) and pancreatic cancer mortality [2].
• CONCLUSION: An early first birth a low number of births and a high weight gain during pregnancies can be assumed as risk factors for overweight, a higher amount of adipose tissue, android fat patterning and therefore for the development of the metabolic syndrome during postmenopause [3].
• BACKGROUND: A European multicenter study (Surveillance of Cerebral Palsy in Europe, SCPE) was used to describe changes over time in multiple birth rates and cerebral palsy (CP) rates among multiple born infants, to compare CP rates and clinical types between multiples and singletons, and to analyse the influence of birth order in twins [4].
• Early age at first birth, increasing parity, and tamoxifen use are related to long-term lifetime reduction in breast-cancer risk [5].

High impact information on Birth Order

• We demonstrate that projection neurons are prespecified by lineage and birth order to form synapses with specific incoming ORN axons, and therefore to carry specific olfactory information [6].
• We propose models to suggest how birth order, HLH-2 accumulation, and transcription of lag-2 may be linked during the AC/VU decision [7].
• We were able to identify a group of women at increased risk of ER+ breast cancers (high-risk group) on the basis of baseline as well as reproductive and hormonal characteristics (height, age at menarche, parity, age at first birth, and oophorectomy) [8].
• Parity, total number of children, age at first birth, and OC use were not associated with an increased risk of RA in this cohort [9].
• A further note on testing for a birth order effect in ankylosing spondylitis [10].

Chemical compound and disease context of Birth Order

• The possible role of environmental factors in the aetiology of these conditions was investigated by studying birth order, symptoms of vitamin A deficiency (night blindness), drug use and maternal illness in pregnancy, rubella antibodies and exposure to agricultural chemicals [11].

Biological context of Birth Order

• In humans, birth order and maternal age as risk factors for ankylosing spondylitis (AS) have not been investigated previously [12].
• The relationship between potential risk factors, including age, age at menarche, parity, age at first birth, total lifetime history of breast-feeding, use of OCs, and irregular menstrual cycles and the multivariate-adjusted risk of RA was estimated using Cox proportional hazards models [9].
• The risk of ventricular septal defect was not significantly associated with gestational age, birth weight, birth order, maternal age, diabetes, smoking, exposure to drugs or infection, paternal age, familial congenital heart disease, religion or consanguinity [13].
• HDL cholesterol declines of -3 to -4 mg/dl after a first birth persisted during the 10 years of follow-up independent of weight, central adiposity, and selected behavior changes [14].
• It has been hypothesized that this fraternal birth order effect reflects the progressive immunization of some mothers to Y-linked minor histocompatibility antigens (H-Y antigens) by each succeeding male fetus and the concomitantly increasing effects of such maternal immunization on the future sexual orientation of each succeeding male fetus [15].

Associations of Birth Order with chemical compounds

• At 57 and 69 wk, lower retinol and RBP correlated with higher birth order [16].
• Multivariate models adjusting for race, sex, birth order, and maternal height, body mass, education, and age indicated that children of smokers were 0.3, 0.3, and 0.8 cm shorter in the lowest, middle, and highest tertile of serum cotinine, respectively, and children of ETS-exposed women were 0.5 cm taller than those of nonsmokers [17].
• After controlling for age, body mass index (weight/height2), and alcohol use, we observed inverse associations between estrone sulfate and parity (r = -0.15, P = 0.03) and between percent bioavailable estradiol and age at first birth (r = -0.17, P = 0.02) [18].
• Plasma progesterone concentrations and corpus luteum volume increased during pregnancy to reach a maximum about 6 days before the first births [19].
• The results suggest that (1) the brain-pituitary-adrenal axis of this altricial bird becomes fully functional after hatching and (2) birth order within broods influences corticosterone secretion during subsequent stages of development [20].

Gene context of Birth Order

• The mean time between onset of RA and the first birth was 23.6 (SD 3.8) years [21].
• Direct associations with parental diagnosis depend on birth order of the ASP members despite the comparable mean impairment scores for older and younger ADHD siblings [22].
• The children were diagnosed as having SLE in reverse birth order at ages 8, 9, and 11 years [23].
• CONCLUSIONS: These results restrict the range of possible theories of the birth order phenomenon to those that can explain not only why older brothers increase the probability of homosexuality in later-born males but also why older sisters neither enhance this effect nor counteract it [24].
• In a multivariate analysis statistically significant predictors of IDDM in the offspring were the sex of the parent, the year of birth and the birth order of the offspring [25].

Analytical, diagnostic and therapeutic context of Birth Order

• In a historical cohort study the outcome of the first birth after a legal 2nd trimester two-stage abortion induced with saline or prostaglandin F2 alpha was evaluated for 142 nulliparous and 65 parous women [26].
• In epidemiological studies, risk of MS in offspring of small families and in those with an early birth-order position has been reported and interpreted in the context of the hygiene hypothesis, which is that infections at an early age, introduced by older siblings, are protective [27].

References