Very advanced maternal age and morbidity in Victoria, Australia: a population based study

Mary C Carolan, Mary-Ann Davey, Maryanne Biro, Michelle Kealy

BACKGROUND: In Australia, approximately 0.1% of births occur to women 45 years or older and this rate has been increasing in recent years. There are however, few population based studies examining perinatal outcomes among this age group. The aim of this study was to determine the maternal and perinatal outcomes of pregnancies in women aged 45 years or older compared to women aged 30--34 years. METHODS: Data on births at 20 or more weeks' gestation were obtained from the Victorian Perinatal Data Collection for the years 2005 and 2006. We examined selected maternal and perinatal outcomes for women of very advanced maternal age (VAMA) aged 45 years or older (n = 217) and compared them to women aged 30--34 years (n = 48,909). Data were summarised using numbers and percentages. Categorical data were analysed by Chi-square tests and Fisher's exact test. Comparisons are presented using unadjusted odds ratios, 95 percent confidence intervals (CIs) and p-values. RESULTS: Women aged 45 years and older had higher odds of gestational diabetes (OR 2.05; 95% CI 1.3--3.3); antepartum haemorrhage (OR 1.89; 95% CI 1.01--3.5), and placenta praevia (OR 4.88; 95% CI 2.4--9.5). The older age-group also had higher odds of preterm birth between 32--36 weeks (OR 2.61; 95% CI 1.8--3.8); low birth-weight (<2,500 gr) (OR 2.22; 95% CI 1.5--3.3) and small for gestational age (OR 1.53; 95% CI 1.0--2.3). Stratified analysis revealed that VAMA was most strongly associated with caesarean section in primiparous women (OR 8.24; 95%CI 4.5, 15.4) and those using ART (OR 5.75; 95%CI 2.5, 13.3), but the relationship persisted regardless of parity, ART use and plurality. Low birthweight was associated with VAMA only in first births (OR 3.90; 95%CI 2.3, 6.6), while preterm birth was more common in older women for both first (OR 3.13; 95%CI 1.8, 5.3) and subsequent (OR 2.08; 95%CI 1.2, 3.5) births, and for those having singleton births (OR 2.11; 95%CI 1.3, 3.4), and those who did not use ART (OR 2.10; 95%CI 1.3, 3.4). Preterm birth was very common in multiple births and following ART use, regardless of maternal age. CONCLUSIONS: This study demonstrates that women aged 45 years and older, in Victoria, Australia, have higher rates of pregnancy and perinatal complications, compared to women aged 30--34 years.