AIM:To investigate associations between perinatal risk factors and subsequent inflammatory bowel disease (IBD) in children and young adults.METHODS:Record linked abstracts of birth registrations,maternity,day case and inpatient admissions in a defined population of southern England.Investigation of 20 perinatal factors relating to the maternity or the birth:maternal age,Crohn’s disease (CD) or ulcerative colitis (UC) in the mother,maternal social class,marital status,smoking in pregnancy,ABO blood group and rhesus status,pre-eclampsia,parity,the infant’s presentation at birth,caesarean delivery,forceps delivery,sex,number of babies delivered,gestational age,birthweight,head circumference,breastfeeding and Apgar scores at one and five minutes.RESULTS:Maternity records were present for 180 children who subsequently developed IBD.Univariate analysis showed increased risks of CD among children of mothers with CD (P=0.011,based on two cases of CD in both mother and child) and children of mothers who smoked during pregnancy.Multivariate analysis confirmed increased risks of CD among children of mothers who smoked (odds ratio=2.04,95% CI=1.06-3.92) and for older mothers aged 35+ years (4.81,2.32-9.98).Multivariate analysis showed that there were no significant associations between CD and 17 other perinatal risk factors investigated.It also showed that,for UC,there were no significant associations with the perinatal factors studied.CONCLUSION:This study shows an association between CD in mother and child;and elevated risks of CD in children of older mothers and of mothers who smoked. AIM: To investigate associations between perinatal risk factors and subsequent inflammatory bowel disease (IBD) in children and young adults. METHODS: Record linked abstracts of birth registrations, maternity, day case and inpatient admissions in a defined population of southern England. Investigation by 20 perinatal factors relating to the maternity or the birth: maternal age, Crohn’s disease (CD) or ulcerative colitis (UC) in the mother, maternal social class, marital status, smoking in pregnancy, ABO blood group and rhesus status, pre-eclampsia, parity, the infant’s presentation at birth, caesarean delivery, forceps delivery, sex, number of babies delivered, gestational age, birthweight, head circumference, breastfeeding and Apgar scores at one and five minutes.RESULTS: maternity records were present for 180 children developed IBD. Univariate analysis of increased risks of CD among children of mothers with CD (P = 0.011, based on two cases of CD in both mother and child) and children of mo thers who smoked during pregnancy. Multivariate analysis confirmed increased risks of CD among children of mothers who smoked (odds ratio = 2.04, 95% CI = 1.06-3.92) and for older mothers aged 35+ years (4.81, 2.32-9.98) analysis showed that there were no significant associations between CD and 17 other perinatal risk factors investigated. It also showed that, for UC, there were no significant associations with the perinatal factors studied. ; and elevated risks of CD in children of older mothers and of mothers who smoked.