Martina Persson and Dharmintra Pasupathy
Aim: Women without diabetes are at increased risk of pregnancy complications in their first pregnancy. The aim of this study was to investigate if the risk of adverse pregnancy outcomes also differs with parity in women with type 1 diabetes (T1DM). Methods: Population based prospective cohort study of all singleton pregnancies to women with T1DM (n=4092) in Sweden between 1998 and 2007. Data was derived from the Swedish Medical Birth Registry. Outcomes of interest were preeclampsia (PE), gestational hypertension (GH), major malformation, perinatal mortality (PMR), preterm delivery, large for gestational age (LGA), small for gestational age (SGA) and neonatal death. Logistic regression analysis was used to obtain odds ratios (OR) for adverse outcomes in relation to parity. Interaction tests were performed to compare the association of interest in non-diabetic pregnancies. Results: The risk of GH (adjusted OR 0.63 95% CI [0.37-1.05]), major malformation (1.25 [0.88-1.77]), preterm delivery (0.83 [0.70-1.00]) and neonatal death (5.34 [0.57-49.8]) did not differ significantly with parity in women with T1DM. Multiparous women with T1DM had lower risk of PE (0.35 [0.28-0.43]), SGA (0.44 [0.29-0.68]), PMR (0.22 [0.10-0.51]) and significantly increased odds of LGA (1.96 (1.71-2.25). In women without diabetes (n = 905 565) the risk of all outcomes except LGA and neonatal death were significantly lower in multiparous women (p value for interaction < 0.05). Conclusion: Multiparity in women with and without T1DM is associated with reduced risks for most adverse outcomes except LGA. Within the T1DM cohort, the risk for major malformations was slightly increased in offspring of multiparous women.