Risk of Adverse Obstetric and Neonatal Outcomes by Maternal Age: Quantifying Individual and Population Level Risk Using Routine UK Maternity Data.

OBJECTIVE: The objective of this study was to investigate whether moderately increased maternal age is associated with obstetric and neonatal outcome in a contemporary population, and to consider the possible role of co-morbidities in explaining any increased risk. STUDY DESIGN: Secondary analysis of routinely collected data from a large maternity unit in London, UK. Data were available on 51,225 singleton deliveries (≥22 weeks) occurring to women aged ≥20 between 2004 and 2012. Modified Poisson regression was used to estimate risk ratios for the association between maternal age and obstetric and neonatal outcome (delivery type, postpartum haemorrhage, stillbirth, low birthweight, preterm birth, small for gestational age, neonatal unit admission), using the reference group 20-24 years. Population attributable fractions were calculated to quantify the population impact. RESULTS: We found an association between increasing maternal age and major postpartum haemorrhage (≥1000ml blood loss) (RR 1.36 95% CI 1.18-1.57 for age 25-29 rising to 2.41 95% CI 2.02-2.88 for age ≥40). Similar trends were observed for caesarean delivery, most notably for elective caesareans (RR 1.64 95% CI 1.36-1.96 for age 25-29 rising to 4.94 95% CI 4.09-5.96 for age ≥40). There was evidence that parity modified this association, with a higher prevalence of elective caesarean delivery in older nulliparous women. Women aged ≥35 were at increased risk of low birthweight and preterm birth. We found no evidence that the risk of stillbirth, small for gestational age, or neonatal unit admission differed by maternal age. CONCLUSIONS: Our results suggest a gradual increase in the risk of caesarean delivery and postpartum haemorrhage from age 25, persisting after taking into account maternal BMI, hypertension and diabetes. The risk of low birthweight and preterm birth was elevated in women over 35. Further research is needed to understand the reasons behind the high prevalence of elective caesarean delivery in nulliparous older mothers.

Ethnic variation in stillbirth risk and the role of maternal obesity: analysis of routine data from a London maternity unit.

BACKGROUND: Approximately 5 in 1,000 deliveries in England and Wales result in stillbirth, with little improvement in figures over the last few decades. The aim of this study was to investigate the association between clinical and socio-demographic factors and stillbirth, with a particular focus on ethnicity and obesity. METHODS: Analysis of routine maternity data on 53,293 singleton births occurring in a large London teaching hospital between 2004 and 2012. Logistic regression was used to investigate risk factors for stillbirth and to explore potential effect modification. RESULTS: 53,293 deliveries occurred during the time period, of which 329 resulted in a stillbirth (6.2 per 1,000 births). Compared to White women, non-White ethnicity was associated with a doubling of the odds of stillbirth (aOR for Black women 2.15, 95% CI 1.56-2.97; aOR for South Asian women 2.33, 95% CI 1.42-3.83). Obese women had a trend towards higher odds of stillbirth compared to women of recommended BMI (aOR 1.38, 95% CI 0.98-1.96), though this was not significant (p 0.07). Both higher parity (≥2 compared to para 1) and hypertension were associated with a higher odds of stillbirth (parity ≥2 aOR 1.65, 95% CI 1.13-2.39; hypertension aOR 1.84, 95% CI 1.22-2.78) but there was no evidence that area deprivation or maternal age were independently associated with stillbirth in this population. There was some evidence of effect modification between ethnicity and obesity (p value for interaction 0.06), with obesity a particularly strong risk factor for stillbirth in South Asian women (aOR 4.64, 95% CI 1.84-11.70). CONCLUSIONS: There was a high prevalence of stillbirth in this multi-ethnic urban population. The increased risk of stillbirth observed in non-White women remains after adjusting for other factors. Our finding of possible effect modification between ethnicity and obesity suggests that further research should be conducted in order to improve understanding of the interplay between ethnicity, obesity and stillbirth.