Low dose aspirin is currently recommended by the Australian College of Obstetrics and Gynaecology for pregnant women with pregestational diabetes to reduce the risk of preeclampsia. However recent studies have suggested no reduction and a possible increase in the risk of preeclampsia with aspirin use in this subgroup(1, 2). In addition, an increase in large for gestational age (LGA) babies has been reported with aspirin use in women with diabetes of shorter duration (1, 3). Conflicting data exists regarding the impact of aspirin use on maternal blood loss at delivery (4, 5).
To further investigate the effect of aspirin on these complications we performed a retrospective cohort study. We included all singleton, live born pregnancies of women with pregestational diabetes delivering at King Edward Memorial Hospital from 2008 to 2013. Data was extracted from the STORK database and medical records. Statistical analysis was performed with SPSS (Version 29.0).
Of 640 pregnancies, aspirin was prescribed in 162 (25.3%) and preeclampsia occurred in 97 (15.2%). Use of aspirin vs no aspirin in our cohort was associated with a higher rate of preeclampsia (28.4% vs 10.7%, p<0.001), increased mean estimated blood loss (630.1ml vs 551.0ml, p=0.041) and increased mean birth centile (73.8 vs 67.6, p=0.036). Parity and body mass index (BMI) had little effect on preeclampsia risk on univariate analysis. The increase in preeclampsia with aspirin use remained after adjusting for type of diabetes and HbA1c (OR 3.17 95% CI 1.98 to 5.07) p <0.001).
After excluding pregnancies with preeclampsia, aspirin use was associated with more LGA babies (55.0% vs 42.2% p=0.017) and placental weight above the 90th centile (62.1% vs 52.3%, p =0.077). However, after adjusting for type of diabetes and HbA1c the association between aspirin and LGA was no longer statistically significant.
Preeclampsia (19.0% vs 13.7%, p=0.056), placental weight (728.3g vs 671.7g, p<0.001), birth weight (3349.3g vs 3168.7g, p=0.003), birth centile (79.2 vs 63.2, p<0.01) and LGA (58.3% vs 37.3%, p<0.01) were more prevalent in women with type 1 compared with type 2 diabetes.
Conclusions: Aspirin use was associated with increased placental centiles, preeclampsia and blood loss in women with pregestational diabetes. These maternal and offspring complications highlight the need to review the current recommendation of aspirin for all pregnant women with diabetes. Adequately powered prospective studies are required to confirm these findings and investigate the possible mechanisms of these effects of aspirin in women with pregestational diabetes.