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Correlations of birth weight and gestational age across generations
P Magnus1, L S Bakketeig, R Skjaerven
1Department of Epidemiology, National Institute of Public Health, Oslo, Norway.
Insights
Maternal birth weight predicts offspring birth weight, but preterm birth risk does not recur across generations. Low birth weight in mothers significantly increases offspring low birth weight risk.
Area of Science:
- Reproductive biology
- Human genetics
- Perinatal epidemiology
Background:
- Maternal birth weight is a known predictor of offspring birth weight.
- The recurrence risk of preterm birth and low birth weight across generations is less understood.
- Understanding intergenerational influences on birth outcomes is crucial for public health.
Purpose of the Study:
- To estimate the recurrence risk of low birth weight and preterm birth across generations.
- To investigate the influence of maternal birth characteristics on offspring birth outcomes.
- To differentiate the heritability of birth weight versus gestational age.
Main Methods:
- Population-based study using linked birth records from the Norwegian Birth Registry.
- Inclusion of 11,092 mother-firstborn offspring pairs.
- Statistical analysis including correlation coefficients and odds ratios to assess recurrence risks.
Main Results:
- A low correlation (0.086) was observed for gestational age across generations.
- A moderate correlation (0.242) was found between maternal and offspring birth weight.
- Mothers with low birth weight (<2500g) had a 3.03-fold increased risk of having a low birth weight child.
- Maternal preterm birth did not significantly increase the risk of offspring preterm birth (OR=1.46).
Conclusions:
- Birth weight recurrence across generations is evident, suggesting significant environmental and/or genetic influences.
- Gestational age recurrence is low, indicating minimal influence from shared genetic factors.
- Maternal birth weight is a stronger predictor of offspring birth weight than maternal preterm birth is of offspring preterm birth.
Abstract:
Maternal birth weight is known to be a predictor of offspring birth weight. Less is known about the recurrence of gestational age. In order to estimate the recurrence risk of low birth weight and preterm birth across generations in a population-based sample, 11,092 pairs of mother-firstborn offspring were obtained through an internal linkage in the Norwegian Birth Registry based on the years 1967-1969 (mothers) and 1986-1989 (offspring). A low correlation coefficient of 0.086 was found for gestational age across generations, whereas the correlation between maternal and offspring birth weight was 0.242. Mothers with birth weight below 2500 g had a significantly increased risk (odds ratio = 3.03, 95% conf. interval 1.79-5.11) of having a low birth weight child compared with mothers with birth weight above 4 kg. On the other hand, if the mother was born before the 37th completed week of gestation, the risk of having a preterm child was not significantly increased (odds ratio = 1.46, conf. interval 0.96-2.21) compared with mothers who were born at term. Thus, in contrast to birth weight, human variation in gestational age does not appear to be influenced by genetic factors to any large degree.