| Summary: | This thesis examines the association between maternal age and adverse birth outcomes in the province of British Columbia (Canada). It explores the differential effect of plurality and parity on this association; and describes differences in obstetric interventions and birth outcomes between older mothers living in rural versus urban areas.
Data were obtained from the BC Perinatal Health Program’s Database Registry, 1999-2003. The database includes all births in BC and contains information about maternal demographic characteristics, behavioural and life-style factors, and obstetric history.
Among older mothers with singleton pregnancies, we observed a higher rate of stillbirths, preterm births, small-for-gestational-age babies, and admissions to a neonatal intensive care. The risk of preterm birth and small-for-gestational-age was modified by parity. The relative risk of preterm birth associated with maternal age was higher among primiparae, compared to multiparae. Older primiparae were at elevated risk for SGA; no such association was found among multiparae.
In twin pregnancies, maternal age was not associated with perinatal death, very preterm birth, small-for-gestational-age, or prolonged neonatal intensive care unit admissions (13 days or longer), regardless of parity. However, the results suggest that the risk of these adverse outcomes is lower among older compared to younger primiparae. Chorionicity did not explain these results.
Older mothers living in rural versus urban areas had lower rates of caesarean sections and higher rates of perinatal death; the risk of small-for-gestation-age was lower, whereas large-for-gestational-age was higher. The rates of labour induction, emergency caesarean-section, preterm birth, and NICU admission were similar in both groups. The risk of caesarean-section and perinatal death increased with the distance from the mother’s residence to the nearest hospital with caesarean -section capacity.
This research adds to current knowledge by demonstrating a differential effect of parity on the association between maternal age and preterm birth and small-for-gestational-age among singletons. This is the first population-based study of twins to explore the effect of parity on the association between maternal age and birth outcomes other that preterm birth. In addition, this is the first study to examine the effect of rural or remote residence on birth outcomes among older mothers. === Medicine, Faculty of === Population and Public Health (SPPH), School of === Graduate
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