The risks associated with pregnancy in women aged 35 years or older

The obstetric risks of adverse outcome during pregnancy in women aged greater than or equal to 35 years were quantified using a retrospective analysis of data from 385 120 singleton pregnancies in the North West Thames Region, UK, between 1988 and 1997, A comparison of pregnancy outcome was made on the basis of maternal age at delivery: 18-34 years (n = 336 462), 35-40 years (n = 41 327) and women aged >40 years (n = 7331). Women aged <18 years (n = 5246) were excluded from the study. Data are presented as percentages of 18-34 year old women, 35-40 year old and >40 year old women, with adjusted odds ratios (OR) according to age group. Pregnant women aged 35-40 years were at increased risk of: gestational diabetes, OR = 2.63 [99% confidence interval (CI) 2.40-2.89]; placenta praevia = 1.93 (1.58-2.35); breech presentation = 1.37 (1.28-1.47); operative vaginal delivery = 1.5 (1.43-1.57); elective Caesarean section = 1.77 (1.68-1.87); emergency Caesarean section = 1.59 (1.52-1.67); postpartum haemorrhage = 1.14 (1.09-1.19); delivery before 32 weeks gestation = 1.41 (1.24-1.61); birthweight below the 5th centile = 1.28 (1.20-1.36); and stillbirth = 1.41 (1.17-1.70). Women aged >40 years had higher OR for the same risks. Pregnant women aged greater than or equal to 35 years are at increased risk of complications in pregnancy compared with younger women.