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Birth order and parental age in microphthalmos and other ocular diseases
Insights
Birth order and maternal age influence congenital blindness risk. First-born children showed lower microphthalmos rates, while older mothers (30s) had higher incidence of certain childhood blindness conditions.
Area of Science:
- Ophthalmology
- Pediatrics
- Epidemiology
Background:
- Congenital blindness presents significant challenges in childhood development.
- Understanding etiological factors, including birth order and maternal age, is crucial for prevention strategies.
Purpose of the Study:
- To investigate the association between birth order, maternal age, and the incidence of congenital blindness in Japanese children.
- To compare these distributions with control groups of the general population and children with acquired blindness.
Main Methods:
- Comparative analysis of birth order and maternal/paternal age distributions.
- Statistical comparison using chi-square tests between blind school children and control populations in Japan.
Main Results:
- A statistically significant lower incidence of microphthalmos was observed in first-born children, with a higher incidence in second- to fourth-born children.
- Amblyopia, congenital cataract, and optic nerve atrophy showed a trend towards higher incidence in first-borns.
- Maternal age distribution differed, with increased incidence of microphthalmos, congenital cataract, corneal opacity, and optic nerve atrophy in children born to mothers in their 30s compared to their 20s.
Conclusions:
- Birth order and maternal age are significant factors associated with specific types of congenital blindness.
- These findings may correlate with declining infant mortality and congenital blindness rates in Japan.
Abstract:
We compared the distribution of birth order and maternal and paternal ages of blind school children throughout Japan with that of the total Japanese population of the corresponding age groups and with that of a subgroup of children with acquired blindness. The number of first-born children with microphthalmos was smaller, and the number of second-, third-, or fourth-born children was larger, as compared with the control groups. The differences were highly statistically significant by chi-square test. There was a less pronounced indication of birth order effect in amblyopia, congenital cataract, and optic nerve atrophy, which involved more first-borns than in the controls. The distribution of maternal age was also different from the control group in microphthalmos, congenital cataract, corneal opacity, and optic nerve atrophy. Less mothers in their 20s and more in their 30s produced children with these conditions. We believe this finding may be partly related to the rapid decline in infant mortality and in the incidence of congenital blindness in Japan.