To describe the prevalence, pregnancy outcome and survival of higher order multiple pregnancies.Methods
Epidemiological analysis of data prospectively notified to the Northern Survey of Twin and Multiple Pregnancy (NorSTAMP), the only population-based multiple pregnancy register in the UK, during 1998–2011.Results
There were a total of 160 higher order pregnancies (495 fetuses) notified to NorSTAMP during the 14 years comprising 148 (92.5%) triplet pregnancies, 10 (6.3%) quadruplets, one (0.6%) quintuplet and one (0.6%) sextuplet pregnancy. The prevalence of triplet maternities decreased from 4.2 per 10,000 maternities in 1998–2004 to 1.9 per 10,000 maternities in 2005–2011 (RR = 0.45, 95% CI 0.31–0.64, p < 0.0001).Results
From a total of 444 triplets, there were 71 spontaneous fetal losses (<24 weeks), 13 feticides or terminations of pregnancy and 340 live births. There were 20 stillbirths (17 antepartum, three intrapartum) and 19 infant deaths (nine early neonatal, five late neonatal and five postneonatal). The overall extended perinatal mortality rate (EPMR, stillbirths and neonatal deaths) for triplets was 94.4 per 1000 total births and the infant mortality rate was 55.9 per 1000 live births. The EPMR decreased from 102.5 per 1000 total births in 1998–2004 to 77.6 per 1000 in 2005–2011 (RR = 0.76, 95% CI 0.37–1.57, p = 0.56). Infant mortality decreased from 77.6 per 1000 live births to 9.3 per 1000 over the same periods (RR = 0.12; 95% CI 0.02–0.88, p = 0.01).Conclusion
Triplet rates have significantly decreased during the study period, most likely due to changes in assisted reproductive policies. Mortality outcomes, particularly infant mortality, have improved.