Parity and incidence of diabetes Mellitus Parity and the Risk of Type 2 Diabetes Per Ovesen1, Sidsel Ipsen1, Søren Lundbye-Christensen2, Steen Rasmussen3, Lone Krebs3, Niels Jørgen Secher3. 1Department of Obstetrics and Gynecology, Skejby Sygehus, 8200 Aarhus N, University of Aarhus, 2University of Aalborg and 3University of Copenhagen, Denmark Parity and incidence of diabetes Mellitus Abstract The relationship between parity and the risk of diabetes remains controversial. Some investigations show that parity, particularly five or more births, might be associated with higher incidence of diabetes, whereas others found no association. We performed a population-based cohort study including all Danish women who gave birth during year 1982-1983 (n = 100238). The cohort was identified in the National Birth Register and information on maternal age and parity was retracted from the register. The women were followed in the National Patient Register through year 2004 and information on type, date, interval from birth to diagnosis of diabetes was recorded. A total of 1717 cases were diagnosed with diabetes in the follow-up period of 23 years. The women in the study were between 13 and 50 years old at the time of delivery. We grouped the study population according to age: the young (age 13-22 years) comprising 19% of the total births, middle group (23-29 years) comprising 55% of the births and old group (30-50 years) comprising 26% of the births. In all groups there was a significant effect of parity on the development of diabetes. In the middle group we found a 10 fold increased risk of diabetes in the group with 5 or more deliveries. In the old group there was a 4 fold increased risk of diabetes in the group with 5 or more deliveries. In the young group the effect of parity 4 or 5+ is very questionable, because of the very few women in these groups. Still a significant effect of parity in the same order of magnitude as in the middle group was found In conclusion these data shows that parity is associated with an increased risk of diabetes. Table 1 Parity in relation to diabetes 23-29 yr parity + diabetes -diabetes 1 639 (1,4%) 44817 2 535 (1,4%) 37107 3 286 (2,2%) 12429 4 146 (4,6%) 3052 5+ 111 (9,1%) 1107 13-22 yr 30-50 yr BACKGROUND Diabetes is a growing problem in the industrialised world. Most of the cases are due to type 2 diabetes, many of whom are diagnosed in young people. Certain risk factors such as age, adiposity and gestational diabetes are well known. The relationship between parity and diabetes remains controversial. Some – but not all - investigations show that parity, particularly five or more births, might be associated with higher incidence of diabetes. An effect of parity on subsequent risk of diabetes is biologically plausible, because pregnancy is associated with insulin resistance. Whether this metabolic stress during pregnancy confers an increased risk of diabetes or other disease states remains an unsolved question. SUMMARY A total of 1717 cases were diagnosed with diabetes in the follow-up period of 23 years. This correlates to 1.7% of the cohort. We found a 7-fold increased risk of diabetes in the group with 5 or more deliveries compared with 1 delivery. The women in the study were between 13 and 50 years old at the time of delivery. We grouped the study population in age groups: The young (age 13-22 years) comprising 19% of the total births, middle group (23-29 years) comprising 55% of the births and old group (30-50 years) comprising 26% of the births. In all groups there was a significant effect of parity on the development of diabetes. In the middle group we found a 10 fold increased risk of diabetes in the group with 5 or more deliveries. In the old group there was a 4 fold increased risk of diabetes in the group with 5 or more deliveries. In the young group the effect of parity 4 or 5+ is very questionable, because of the low sample size. Still a significant effect of parity in the same order of magnitude as in the middle group was found CONCLUSION These data shows that parity is associated with an increased risk of diabetes AIM To evaluate the relationship between parity and incidence of diabetes in a Danish register study. % diabetes DESIGN and METHODS We performed a population-based cohort study including all Danish women who gave birth during year 1982-1983. The cohort was identified in the National Birth Register and information on maternal age and parity was retracted from the register. 100.238 cases were included in the study, all non-diabetics. The women were followed in the National Patient Register through year 2004 and information on type, date, interval from birth to diagnosis of diabetes was recorded Age (years)