Maternal characteristics
424 pregnancy pairs were analysed: 170 pairs from RHW (centre 1) and 254 pregnancy pairs from BMDH (centre 2). A total of 807 pregnancies in 375 women were studied, with 31 women having three GDM pregnancies and five having four GDM pregnancies.
Maternal characteristics in index and subsequent GDM pregnancies are shown in Table 1. The mean age was 30.6±4.9 years in the index pregnancy and 33.5±4.9 years in the subsequent pregnancy. Booking-in weight and BMI were higher in the subsequent pregnancy (p<0.001), and GDM was diagnosed 3 weeks earlier (p<0.001) with a higher rate of early GDM (42.5% vs 9.7%, p<0.001). The rate of medication use (insulin, metformin or both) was higher in the subsequent pregnancy (63.7% vs 54.0%, p<0.001) and medication was started 3 weeks earlier (p<0.001). There were no differences in GTT results in the index versus subsequent pregnancy.
While there were some minor differences in maternal characteristics between the two centres, interpregnancy changes were generally comparable. The mean increment in age between index and subsequent pregnancies was slightly smaller in centre 1 versus centre 2 (2.6±1.3 vs 3.1±1.7 years, p=0.001). Similarly, the mean increment in body weight at booking-in (the first antenatal visit) was smaller in centre 1 (1.8±5.7 vs 3.1±6.1 kg, p=0.03). There were no significant differences in interval changes between centres for other maternal parameters including BMI at booking-in and glucose levels on the GTT.